Author name code: dravins
ADS astronomy entries on 2022-09-14
author:"Dravins, Dainis" 
------------------------------------------------------------------------  

Title: CTA – the World's largest ground-based gamma-ray observatory
Authors: Zanin, R.; Abdalla, H.; Abe, H.; Abe, S.; Abusleme, A.;
   Acero, F.; Acharyya, A.; Acin Portella, V.; Ackley, K.; Adam, R.;
   Adams, C.; Adhikari, S. S.; Aguado Ruesga, I.; Agudo, I.; Aguilera,
   R.; Aguirre Santaella, A.; Aharonian, F.; Alberdi, A.; Alfaro, R.;
   Alfaro, J.; Alispach, C.; Aloisio, R.; Alves Batista, R.; Amans,
   J. P.; Amati, L.; Amato, E.; Ambrogi, L.; Ambrosi, G.; Ambrosio, M.;
   Ammendola, R.; Anderson, J.; Anduze, M.; Anguner, E. O.; Antonelli,
   L. A.; Antonuccio, V.; Antoranz, P.; Anutarawiramkul, R.; Aragunde
   Gutierrez, J.; Aramo, C.; Araudo, A.; Araya, M.; Arbet Engels, A.;
   Arcaro, C.; Arendt, V.; Armand, C.; Armstrong, T.; Arqueros, F.;
   Arrabito, L.; Arsioli, B.; Artero, M.; Asano, K.; Ascasibar, Y.;
   Aschersleben, J.; Ashley, M.; Attina, P.; Aubert, P.; Singh, C. B.;
   Baack, D.; Babic, A.; Backes, M.; Baena, V.; Bajtlik, S.; Baktash,
   A.; Balazs, C.; Balbo, M.; Ballester, O.; Ballet, J.; Balmaverde, B.;
   Bamba, A.; Bandiera, R.; Baquero Larriva, A.; Barai, P.; Barbier, C.;
   Barbosa Martins, V.; Barcelo, M.; Barkov, M.; Barnard, M.; Baroncelli,
   L.; Barres de Almeida, U.; Barrio, J. A.; Bastieri, D.; Batista, P. I.;
   Batkovic, I.; Bauer, C.; Bautista González, R.; Baxter, J.; Becciani,
   U.; Becerra González, J.; Becherini, Y.; Beck, G.; Becker Tjus, J.;
   Bednarek, W.; Belfiore, A.; Bellizzi, L.; Belmont, R.; Benbow, W.;
   Berge, D.; Bernardini, E.; Bernardos, M. I.; Bernlöhr, K.; Berti,
   A.; Berton, M.; Bertucci, B.; Beshley, V.; Bhatt, N.; Bhattacharyya,
   S.; Bhattacharyya, W.; Bhattacharyya, S.; Bi, B. Y.; Bicknell, G.;
   Biederbeck, N.; Bigongiari, C.; Biland, A.; Bird, R.; Bissaldi, E.;
   Biteau, J.; Bitossi, M.; Blanch, O.; Blank, M.; Blazek, J.; Bobin,
   J.; Boccato, C.; Bocchino, F.; Boehm, C.; Bohacova, M.; Boisson, C.;
   Boix, J.; Bolle, J. P.; Bolmont, J.; Bonanno, G.; Bonavolontà, C.;
   Bonneau Arbeletche, L.; Bonnoli, G.; Bordas, P.; Borkowski, J.; Bose,
   R.; Bose, D.; Bosnjak, Z.; Bottacini, E.; Böttcher, M.; Botticella,
   M. T.; Boutonnet, C.; Bouyjou, F.; Bozhilov, V.; Bozzo, E.; Brahimi,
   L.; Braiding, C.; Brau Nogue, S.; Breen, S.; Bregeon, J.; Breuhaus,
   M.; Brill, A.; Brisken, W.; Brocato, E.; Brown, A. M.; Brügge, K.;
   Brun, P.; Brun, F.; Brunetti, L.; Brunetti, G.; Bruno, P.; Bruno,
   A.; Bruzzese, A.; Bucciantini, N.; Buckley, J. H.; Bühler, R.;
   Bulgarelli, A.; Bulik, T.; Bünning, M.; Bunse, M.; Burton, M.;
   Burtovoi, A.; Buscemi, M.; Buschjager, S.; Busetto, G.; Buss, J.;
   Byrum, K.; Caccianiga, A.; Cadoux, F.; Calanducci, A.; Calderon,
   C.; Calvo Tovar, J.; Cameron, R. A.; Campana, P.; Canestrari, R.;
   Cangemi, F.; Cantlay, B.; Capalbi, M.; Capasso, M.; Cappi, M.;
   Caproni, A.; Capuzzo Dolcetta, R.; Caraveo, P.; Cárdenas, V.;
   Cardiel, L.; Cardillo, M.; Carlile, C.; Caroff, S.; Carosi, R.;
   Carosi, A.; Carquin, E.; Carrere, M.; Casandjian, J. M.; Casanova,
   S.; Cassol, F.; Catalani, F.; Catalano, O.; Cauz, D.; Ceccanti, A.;
   Celestino Silva, C.; Cerny, K.; Cerruti, M.; Chabanne, E.; Chadwick,
   P.; Chai, Y.; Chambery, P.; Champion, C.; Chaty, S.; Chen, A.; Cheng,
   K.; Chernyakova, M.; Chiaro, G.; Chiavassa, A.; Chikawa, M.; Chitnis,
   V. R.; Chudoba, J.; Chytka, L.; Cikota, S.; Circiello, A.; Clark,
   P.; Colak, M.; Colombo, E.; Colonges, S.; Comastri, A.; Compagnino,
   A.; Conforti, V.; Congiu, E.; Coniglione, R.; Conrad, J.; Conte,
   F.; Contreras, J. L.; Coppi, P.; Cornat, R.; Coronado Blazquez,
   J.; Cortina, J.; Costa, A.; Costantini, H.; Cotter, G.; Courty, B.;
   Covino, S.; Crestan, S.; Cristofari, P.; Crocker, R.; Croston, J.;
   Cubuk, K.; Cuevas, O.; Cui, X.; Cusumano, G.; Cutini, S.; D'Amico,
   G.; D'Ammando, F.; D'Avanzo, P.; Da Vela, P.; Dadina, M.; Dai, S.;
   Dalchenko, M.; Dall'Ora, M.; Daniel, M. K.; Dauguet, J.; Davids, I.;
   Davies, J.; Dawson, B.; De Angelis, A.; de Araujo Carvalho, A. E.;
   de Bony de Lavergne, M.; De Cesare, G.; de Frondat, F.; de la Calle,
   I.; de Gouveia Dal Pino, E.; De Lotto, B.; De Luca, A.; De Martino,
   D.; de Naurois, M.; de Ona Wilhelmi, E.; De Palma Persio, F.; De
   Simone, N.; de Souza Valle, V.; Delagnes, E.; Deleglise Reznicek,
   G.; Delgado, C.; Delgado Giler, A. G.; Delgado Mengual Valle, J.;
   della Volpe, D.; Depaoli, D.; Devin, J.; Di Girolamo, T.; Di Giulio
   Pierro, C.; Di Venere, L.; Díaz, C.; Dib, C.; Diebold, S.; Digel,
   S.; Djannati Atai, A.; Djuvsland, J.; Dmytriiev, A.; Docher, K.;
   Domínguez, A.; Dominis Prester, D.; Donini, A.; Dorner, D.; Doro,
   M.; dos Anjos, R. d. C.; Dournaux, J. L.; Downes, T.; Drake, G.;
   Drass, H.; Dravins, D.; Duangchan, C.; Duara, A.; Dubus, G.; Ducci,
   L.; Duffy, C.; Dumora, D.; Dundas Mora, K.; Durkalec, A.; Dwarkadas,
   V. V.; Ebr, J.; Eckner, C.; Eder, J.; Edy, E.; Egberts, K.; Einecke,
   S.; Eleftheriadis, C.; Elsässer, D.; Emery, G.; Emmanoulopoulos, D.;
   Ernenwein, J. P.; Errando, M.; Escarate, P.; Escudero, J.; Espinoza,
   C.; Ettori, S.; Eungwanichayapant, A.; Evans, P.; Evoli, C.; Fairbairn,
   M.; Falceta Goncalves, D.; Falcone, A.; Fallah Ramazanı, V.; Falomo,
   R.; Farakos, K.; Fasola, G.; Fattorini, A.; Favre, Y.; Fedora, R.;
   Fedorova, E.; Feijen, K.; Feng, Q.; Ferrand, G.; Ferrara, G.; Ferreira,
   O.; Fesquet, M.; Fiandrini, E.; Fiasson, A.; Filipovic, M.; Fink, D.;
   Finley, J. P.; Fioretti, V.; Fiorillo, D. F. G.; Fiorini, M.; Flis, S.;
   Flores, H.; Foffano, L.; Fohr, C.; Fonseca, M. V.; Font, L.; Fontaine,
   G.; Fornieri, O.; Fortin, P.; Fortson, L.; Fouque, N.; Fraga, B.;
   Franceschini, A.; Franco, F. J.; Freixas Coromina, L.; Fresnillo, L.;
   Fugazza, D.; Fujita, Y.; Fukami, S.; Fukazawa, Y.; Fulla, D.; Funk,
   S.; Furniss, A.; Gabici, S.; Gaggero, D.; Galanti, G.; Galdemard,
   P.; Gallant, Y. A.; Galloway, D.; Gallozzi, S.; Gammaldi, V.; Garcia,
   R.; Garcia, E.; Garcia Lopez, E.; Gargano, F.; Gargano, C.; Garozzo,
   S.; Gascon, D.; Gasparetto, T.; Gasparrini, D.; Gasparyan, H.; Gaug,
   M.; Geffroy, N.; Gent, A.; Germani, S.; Ghalumyan, A.; Ghedina, A.;
   Ghirlanda, G.; Gianotti, F.; Giarrusso, S.; Giarrusso, M.; Giavitto,
   G.; Giebels, B.; Giglietto, N.; Gika, V.; Gillardo, F.; Gimenes,
   R.; Giordano, F.; Giro, E.; Giroletti, M.; Giuliani, A.; Gjaja,
   M.; Glicenstein, J. F.; Gliwny, P.; Goksu, H.; Goldoni, P.; Gomez,
   J. L.; Gonzalez, M. M.; Gonzalez, J. M.; Gothe, K. S.; Gotz Coelho,
   D.; Grabarczyk, T.; Graciani, R.; Grandi, P.; Grasseau, G.; Grasso,
   D.; Green, D.; Green, J.; Greenshaw, T.; Grespan, P.; Grillo, A.;
   Grondin, M. H.; Grube, J.; Guarino, V.; Guest, B.; Gueta, O.; Günduz,
   M.; Gunji, S.; Gyuk, G.; Hackfeld, J.; Hadasch, D.; Hagge, L.; Hahn,
   A.; Hajlaoui, J. E.; Halim, A.; Hamal, P.; Hanlon, W.; Harada, Y.;
   Hardcastle, M. J.; Collado, M. Harvey; Haubold, T.; Haupt, A.; Havelka,
   M.; Hayashi, K.; Hayashi, K.; Hayashida, M.; He, H.; Heckmann, L.;
   Heller, M.; Henault, F.; Henri, G.; Hermann, G.; Hernández Cadena, S.;
   Herrera Llorente, J.; Hervet, O.; Hinton, J.; Hiramatsu, A.; Hirotani,
   K.; Hnatyk, B.; Hnatyk, R.; Hoang, J. K.; Hoffmann, D. H. H.; Hoischen,
   C.; Holder, J.; Holler, M.; Hona, B.; Horan, D.; Horns, D.; Horvath,
   P.; Houles, J.; Hrabovsky, M.; Hrupec, D.; Huang, Y.; Huet, J. M.;
   Hughes, G.; Hull, G.; Humensky, T. B.; Hütten, M.; Iarlori, M.; Illa,
   J. M.; Imazawa, R.; Inada, T.; Incardona, F.; Ingallinera, A.; Inoue,
   S.; Inoue, T.; Inoue, Y.; Iocco, F.; Ioka, K.; Ionica, M.; Iovenitti,
   S.; Iriarte, A.; Ishio, K.; Ishizaki, W.; Iwamura, Y.; Jacquemier, J.;
   Jacquemont, M.; Jamrozy, M.; Janecek, P.; Jankowsky, F.; JardinBlicq,
   A.; Jarnot, C.; Martínez, P. Jean; Jocou, L.; Jordana, N.; Josselin,
   M.; JungRichardt, I.; Junqueira, F. J. P. A.; Juramy Gilles, C.;
   Kaaret, P.; Kadowaki, L. H. S.; Kagaya, M.; Kankanyan, R.; Kantzas, D.;
   Karas, V.; Karastergiou, A.; Karkar, S.; Kasperek, J.; Katagiri, H.;
   Kataoka, J.; Katarzynski, K.; Katsuda, S.; Kawanaka, N.; Kazanas, D.;
   Kerszberg, D.; Khélifi, B.; Kherlakian, M. C.; Kian, T. P.; Kieda,
   D. B.; Kihm, T.; Kim, S.; Kisaka, S.; Kissmann, R.; Kleijwegt, R.;
   Kluge, G.; Kluźniak, W.; Knapp, J.; Kobakhidze, A.; Kobayashi, Y.;
   Koch, B.; Kocot, J.; Kohri, K.; Komin, N.; Kong, A.; Kosack, K.; Krack,
   F.; Krause, M.; Krennrich, F.; Kubo, H.; Kudryavtsev, V. N.; Kunwar,
   S.; Kushida, J.; Kushwaha, P.; Parola, B.; La Rosa, G.; Lahmann, R.;
   Lamastra, A.; Landoni, M.; Landriu, D.; Lang, R. G.; Lapington, J.;
   Laporte, P.; Lason, P.; Lasuik, J.; Lazendic Galloway, J.; Le Flour,
   T.; Le Sidaner, P.; Leach, S.; Lee, S. H.; Lee, W. H.; Oliveira,
   S. Lee; Lemiere, A.; Lemoine Goumard, M.; Lenain, J. P.; Leone,
   F.; Leray, V.; Leto, G.; Leuschner, F.; Lindemann, R.; Lindfors,
   E.; Linhoff, L.; Liodakis, I.; Lipniacka, A.; Lobo, M.; Lohse, T.;
   Lombardi, S.; Lopez, A.; Lopez, M.; Lopez Coto, R.; Louis, F.; Louys,
   M.; Lucarelli, F.; Boudi, H. Ludwig; Luque Escamilla, P. L.; Maccarone,
   M. C.; Mach, E.; Maciejewski, A. J.; Mackey, J.; Maeght, P.; Maggio,
   C.; Maier, G.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Malta Nunes
   de Almeida, R.; Malyshev, D.; Malyshev, D.; Mandat, D.; Maneva, G.;
   Manganaro, M.; Manigot, P.; Mannheim, K.; Maragos, N.; Marano, D.;
   Marconi, M.; Marcowith, A.; Marculewicz, M.; Marcun, B.; Marin, J.;
   Marinello, N.; Marinos, P.; Markoff, S.; Marquez, P.; Marsella, G.;
   Martin, J. M.; Martin, P. G.; Martinez, M.; Martinez, G.; Martinez,
   O.; Martinez Huerta, H.; Marty, C.; Marx, R.; Masetti, N.; Massimino,
   P.; Matsumoto, H.; Matthews, N.; Maurin, G.; Moerbeck, W. Max; Maxted,
   N.; Mazziotta, M. N.; Mazzola, S. M.; Mbarubucyeye, J. D.; Mc Comb,
   L.; McHardy, I.; McKeague, S.; McMuldroch, S.; Medina, E.; Medina
   Miranda, D.; Melandri, A.; Melioli, C.; Melkumyan, D.; Menchiari,
   S.; Mereghetti, S.; Merino Arevalo, G.; Mestre, E.; Meunier, J. L.;
   Meures, T.; Micanovic, S.; Miceli, M.; Michailidis, M.; Michalowski,
   J.; Miener, T.; Mievre, I.; Miller, J. D.; Mineo, T.; Minev, M.;
   Miranda, J. M.; Mitchell, A.; Mizuno, T.; Mode, B. A.; Moderski, R.;
   Mohrmann, L.; Molinari, E.; Montaruli, T.; Monteiro, I.; Moore, C.;
   Moralejo, A.; Morcuende Parrilla, D.; Moretti, E.; Mori, K.; Moriarty,
   P.; Morik, K.; Morris, P.; Morselli, A.; Mosshammer, K.; Mukherjee,
   R.; Muller, J.; Mundell, C.; Mundet, J.; Murach, T.; Muraczewski,
   A.; Muraishi, H.; Musella, I.; Musumarra, A.; Nagai, A.; Nagataki,
   S.; Naito, T.; Nakamori, T.; Nakashima, K.; Nakayama, K.; Nakhjiri,
   N.; Naletto, G.; Naumann, D.; Nava, L.; Nawaz, M. A.; Ndiyavala,
   H.; Neise, D.; Nellen, L.; Nemmen, R.; Neyroud, N.; Ngernphat, K.;
   Nguyen Trung, T.; Nicastro, L.; Nickel, L.; Niemiec, J.; Nieto, D.;
   Nigro, C.; Nikołajuk, M.; Ninci, D.; Noda, K.; Nogami, Y.; Nolan,
   S.; Norris, R. P.; Nosek, D.; Nöthe, M.; Novotny, V.; Nozaki, S.;
   Nunio, F.; O'Brien, P.; Obara, K.; Ohira, Y.; Ohishi, M.; Ohm, S.;
   Oka, T.; Okazaki, N.; Okumura, A.; Oliver, C.; Olivera, G.; Olmi, B.;
   Orienti, M.; Orito, R.; Orlandini, M.; Orlando, E.; Osborne, J. P.;
   Ostrowski, M.; Otte, N.; Ovcharov, E.; Owen, E.; Oya, I.; Ozieblo, A.;
   Padovani, M.; Pagliaro, A.; Paizis, A.; Palatiello, M.; Palatka, M.;
   Palazzi, E.; Panazol, J. L.; Paneque, D.; Panny, S.; Pantaleo, F. R.;
   Panter, M.; Paolillo, M.; Papitto, A.; Paravac, A.; Paredes, J. M.;
   Pareschi, G.; Parmiggiani, N.; Parsons, R. D.; Paśko, P.; Patel,
   S. R.; Patricelli, B.; Pavletic, L.; Pavy, S.; Peer, A.; Pecimotika,
   M.; Pellegriti, M. G.; Peñil Del Campo, P.; Pepato, A.; Perard, S.;
   Perennes, C.; Peresano, M.; Perez Aguilera, A.; Perez Romero, J.;
   Perez Torres, M. A.; Persic, M.; Petrucci, P. O.; Petruk, O.; Peyaud,
   B.; Pfrang, K.; Pian, E.; Piatteli, P.; Pietropaolo, E.; Pillera, R.;
   Pimentel, D.; Pintore, F.; Garcia, C. Pio; Pirola, G.; Piron, F.; Pita,
   S.; Pohl, M.; Poireau, V.; Pollo, A.; Polo, M.; Pongkitivanichkul, C.;
   Porthault, J.; Powell, J.; Pozo, D.; Prado, R. R.; Prandini, E.; Prast,
   J.; Pressard, K.; Principe, G.; Produit, N.; Prokhorov, D.; Prokoph,
   H.; Przybilski, H.; Pueschel, E.; Pühlhofer, G.; Puljak, I.; Pumo,
   M. L.; Punch, M.; Queiroz, F.; Quinn, J.; Quirrenbach, A.; Rajda,
   P. J.; Rando, R.; Razzaque, S.; Recchia, S.; Reichherzer, P.; Reimer,
   O.; Reisenegger, A.; Remy, Q.; Renaud, M.; Reposeur, T.; Reville,
   B.; Reymond, J. M.; Reynolds, J.; Ribeiro, D.; Ribo, M.; Richards,
   G.; Rico, J.; Rieger, F.; Riitano, L.; Riquelme, M.; Riquelme, D.;
   Rivoire, S.; Rizi, V.; Roache, E.; Roche, M.; Rodriguez, J.; Rodriguez
   Fernandez, G.; Rodriguez Ramirez, J. C.; Rodriguez Vazquez, J. J.;
   Rojas, G.; Romano, P.; Romeo Lobato, G.; Romoli, C.; Roncadelli,
   M.; Rosado, J.; Rosales de Leon, A.; Rowell, G.; Rugliancich, A.;
   Ruiz del Mazo, J. E.; Rulten, C.; Russell, C.; Russo Hatlen, F.;
   Safi Harb, S.; Saha, L.; Sahakian, V.; Sailer, S.; Saito, T.; Sakaki,
   N.; Sakurai, S.; Salina, G.; Salzmann, H.; Sanchez, D.; Sandaker, H.;
   Sandoval, A.; Sangiorgi, P.; Sanguillon, M.; Sano, H.; Santander, M.;
   Santangelo, A.; Santos Lima, R.; Sanuy, A.; Sapozhnikov, L.; Saric,
   T.; Sarkar, S.; Sasaki, H.; Sasaki, N.; Sato, Y.; Saturni, F. G.;
   Sawada, M.; Schaefer, J.; Scherer, A.; Scherpenberg, J.; Schipani,
   P.; Schleicher, B.; Schmoll, J.; Schneider, M.; Schoorlemmer, H.;
   Schovanek, P.; Schussler, F.; Schwab, B.; Schwanke, U.; Schwarz, J.;
   Sciacca, E.; Scuderi, S.; Seglar Arroyo, M.; Seitenzahl, I.; Semikoz,
   D.; Sergijenko, O.; Serna Franco, J. E.; Seweryn, K.; Sguera, V.;
   Shalchi, A.; Shang, R. Y.; Sharma, P.; Sidoli, L.; Sieiro, J.;
   Siejkowski, H.; Sillanpaa, A.; Singh, B. B.; Singh, K. K.; Sinha,
   A.; Siqueira, C.; Sitarek, J.; Sizun, P.; Sliusar, V.; Sobczynska,
   D.; Sobrinho, R. W.; Sol, H.; Sottile, G.; Spackman, H.; Spencer,
   S.; Spengler, G.; Spiga, D.; Springer, W.; Stamerra, A.; Stanic, S.;
   Starling, R.; Stawarz, Ł.; Stefanik, S.; Stegmann, C.; Steiner, A.;
   Steinmassl, S.; Stella, C.; Sternberger, R.; Sterzel, M.; Stevens, C.;
   Stevenson, B.; Stolarczyk, T.; Stratta, G.; Straumann, U.; Striskovic,
   J.; Strzys, M.; Stuik, R.; Suchenek, M.; Sunada, Y.; Suomijarvi,
   T.; Suric, T.; Suzuki, H.; Swierk, P.; Szepieniec, T.; Tachihara,
   K.; Tagliaferri, G.; Tajima, H.; Tajima, N.; Tak, D.; Takahashi, H.;
   Takahashi, M.; Takata, J.; Takeishi, R.; Tam, T.; Tanaka, M.; Tanaka,
   T.; Tanaka, S.; Tavani, M.; Tavecchio, F.; Tavernier, T.; Taylor,
   A. R.; Tejedor, L. A.; Temnikov, P.; Terauchi, K.; Terrazas, J. C.;
   Terrier, R.; Terzic, T.; Teshima, M.; Thibaut, D.; Thocquenne, F.;
   Tian, W.; Tibaldo, L.; Tiengo, A.; Tluczykont, M.; Todero Peixoto,
   C. J.; Toma, K.; Tomankova, L.; Tomastik, J.; Tornikoski, M.; Torres,
   D. F.; Torresi, E.; Tosti, G.; Tosti, L.; Tothill, N.; Toussenel,
   F.; Tovmassian, G.; Trichard, C.; Trifoglio, M.; Trois, A.; Truzzi,
   S.; Tsiahina, A.; Turk, B.; Tutone, A.; Uchiyama, Y.; Utayarat,
   P.; Vaclavek, L.; Vacula, M.; Vagelli, V.; Vagnetti, F.; Valdivia,
   J. A.; Valentino, M.; Valio, A.; Vallage, B.; Vallania Quispe, P.;
   van den Berg, A. M.; van Driel, W.; van Eldik, C.; van Rensburg,
   C.; van Soelen, B.; Vandenbroucke, J.; Vasileiadis, G.; Vassiliev,
   V.; Vazquez Acosta, M.; Vecchi, M.; Vega, A.; Veh, J.; Veitch, P.;
   Venter, C.; Ventura, S.; Vercellone, S.; Verguilov, V.; Verna, G.;
   Vernetto, S.; Verzi, V.; Vettolani, G. P.; Veyssiere, C.; Viale, I.;
   Viana, A.; Viaux, N.; Vignatti, J.; Vigorito, C. F.; Villanueva, J.;
   Vitale, V.; Vittorini, V.; Vodeb, V.; Vogel, N.; Voisin, V.; Vorobiov,
   S.; Vrastil, M.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Wakazono,
   K.; Wakely, S. P.; Ward, M.; Warren, D.; Watson, J.; Wechakama, M.;
   Wegner, P.; Weinstein, A.; Weniger, C.; Werner, F.; Wetteskind, H.;
   White, M. L.; Wierzcholska, A.; Wiesand, S.; Wijers, R.; Wilkinson,
   M.; Will, M.; Williams, J.; Williamson, T. J.; Wolter, A.; Wong,
   Y. W.; Wood, M.; Yamamoto, T.; Yamamoto, H.; Yamane, Y.; Yamazaki,
   R.; Yanagita, S.; Yang, L.; Yoo, S.; Yoshida, T.; Yoshikoshi, T.;
   Yu, P.; Yusafzai, A.; Zacharias, M.; Zaldivar, B.; Zampieri, L.;
   Zanin, R.; Zanmar Sanchez, R.; Zaric, D.; Zavrtanik, M.; Zavrtanik,
   D.; Zdziarski, A.; Zech, A.; Zechlin, H.; Zenin, A.; Zerwekh, A.;
   Ziętara, K.; Zink, A.; Ziolkowski, J.; Zivec, M.; Zmija, A.
Bibcode: 2022icrc.confE...5Z
Altcode: 2022PoS...395E...5Z
  No abstract at ADS

Title: Astrometric radial velocities for nearby stars
Authors: Lindegren, Lennart; Dravins, Dainis
Bibcode: 2021A&A...652A..45L
Altcode: 2021arXiv210509014L
  Context. Under certain conditions, stellar radial velocities can be
  determined from astrometry, without any use of spectroscopy. This
  enables us to identify phenomena, other than the Doppler effect,
  that are displacing spectral lines. <BR /> Aims: The change of
  stellar proper motions over time (perspective acceleration) is used
  to determine radial velocities from accurate astrometric data, which
  are now available from the Gaia and HIPPARCOS missions. <BR /> Methods:
  Positions and proper motions at the epoch of HIPPARCOS are compared with
  values propagated back from the epoch of the Gaia Early Data Release
  3. This propagation depends on the radial velocity, which obtains its
  value from an optimal fit assuming uniform space motion relative to the
  solar system barycentre. <BR /> Results: For 930 nearby stars we obtain
  astrometric radial velocities with formal uncertainties better than
  100 km s<SUP>−1</SUP>; for 55 stars the uncertainty is below 10 km
  s<SUP>−1</SUP>, and for seven it is below 1 km s<SUP>−1</SUP>. Most
  stars that are not components of double or multiple systems show
  good agreement with available spectroscopic radial velocities. <BR />
  Conclusions: Astrometry offers geometric methods to determine stellar
  radial velocity, irrespective of complexities in stellar spectra. This
  enables us to segregate wavelength displacements caused by the radial
  motion of the stellar centre-of-mass from those induced by other
  effects, such as gravitational redshifts in white dwarfs.

Title: Intensity Interferometry
Authors: Dravins, Dainis
Bibcode: 2021hai3.book...31D
Altcode:
  No abstract at ADS

Title: Spatially resolved spectroscopy across stellar surfaces. IV. F,
G, and K-stars: Synthetic 3D spectra at hyper-high resolution
Authors: Dravins, Dainis; Ludwig, Hans-Günter; Freytag, Bernd
Bibcode: 2021A&A...649A..16D
Altcode: 2021arXiv210303880D
  Context. High-precision stellar analyses require hydrodynamic 3D
  modeling. Such models predict changes across stellar disks of spectral
  line shapes, asymmetries, and wavelength shifts. For testing models in
  stars other than the Sun, spatially resolved observations are feasible
  from differential spectroscopy during exoplanet transits, retrieving
  spectra of those stellar surface segments that successively become
  hidden behind the transiting planet, as demonstrated in Papers I, II,
  and III. <BR /> Aims: Synthetic high-resolution spectra over extended
  spectral regions are now available from 3D models. Similar to other ab
  initio simulations in astrophysics, these data contain patterns that
  have not been specifically modeled but may be revealed after analyses
  to be analogous to those of a large volume of observations. <BR />
  Methods: From five 3D models spanning T<SUB>eff</SUB> = 3964-6726 K
  (spectral types ~K8 V-F3 V), synthetic spectra at hyper-high resolution
  (λ/Δλ &gt;1 000 000) were analyzed. Selected Fe I and Fe II lines at
  various positions across stellar disks were searched for characteristic
  patterns between different types of lines in the same star and for
  similar lines between different stars. <BR /> Results: Spectral-line
  patterns are identified for representative photospheric lines of
  different strengths, excitation potentials, and ionization levels,
  thereby encoding the hydrodynamic 3D structure. Line profiles and
  bisectors are shown for various stars at different positions across
  stellar disks. Absolute convective wavelength shifts are obtained
  as differences to 1D models, where such shifts do not occur. <BR />
  Conclusions: Observable relationships for line properties are retrieved
  from realistically complex synthetic spectra. Such patterns may also
  test very detailed 3D modeling, including non-LTE effects. While present
  results are obtained at hyper-high spectral resolution, the subsequent
  Paper V examines their practical observability at realistically lower
  resolutions, and in the presence of noise.

Title: Spatially resolved spectroscopy across stellar
surfaces. V. Observational prospects: toward Earth-like exoplanet
    detection
Authors: Dravins, Dainis; Ludwig, Hans-Günter; Freytag, Bernd
Bibcode: 2021A&A...649A..17D
Altcode: 2021arXiv210304996D
  Context. High-precision stellar analyses require hydrodynamic 3D
  modeling. Testing such models is feasible by retrieving spectral line
  shapes across stellar disks, using differential spectroscopy during
  exoplanet transits. Observations were presented in Papers I, II, and
  III, while Paper IV explored synthetic data at hyper-high spectral
  resolution for different classes of stars, identifying characteristic
  patterns for Fe I and Fe II lines. <BR /> Aims: Anticipating future
  observations, the observability of patterns among photospheric lines
  of different strength, excitation potential and ionization level are
  examined from synthetic spectra, as observed at ordinary spectral
  resolutions and at different levels of noise. Time variability in 3D
  atmospheres induces changes in spectral-line parameters, some of which
  are correlated. An adequate calibration could identify proxies for
  the jitter in apparent radial velocity to enable adjustments to actual
  stellar radial motion. <BR /> Methods: We used spectral-line patterns
  identified in synthetic spectra at hyper-high resolution in Paper IV
  from 3D models spanning T<SUB>eff</SUB> = 3964-6726 K (spectral types
  ~K8 V-F3 V) to simulate practically observable signals at different
  stellar disk positions at various lower spectral resolutions, down
  to λ/Δλ = 75 000. We also examined the center-to-limb temporal
  variability. <BR /> Results: Recovery of spatially resolved line
  profiles with fitted widths and depths is shown for various noise
  levels, with gradual degradation at successively lower spectral
  resolutions. Signals during exoplanet transit are simulated. In
  addition to Rossiter-McLaughlin type signatures in apparent radial
  velocity, analogous effects are shown for line depths and widths. In
  a solar model, temporal variability in line profiles and apparent
  radial velocity shows correlations between jittering in apparent
  radial velocity and fluctuations in line depth. <BR /> Conclusions:
  Spatially resolved spectroscopy using exoplanet transits is feasible
  for main-sequence stars. Overall line parameters of width, depth and
  wavelength position can be retrieved already with moderate efforts,
  but a very good signal-to-noise ratio is required to reveal the more
  subtle signatures between subgroups of spectral lines, where finer
  details of atmospheric structure are encoded. Fluctuations in line depth
  correlate with those in wavelength, and because both can be measured
  from the ground, searches for low-mass exoplanets should explore these
  to adjust apparent radial velocities to actual stellar motion.

Title: Spatially Resolved Stellar Disk Spectra at Hyper-high
Resolution: Toward Earth-like Exoplanet Detection
Authors: Dravins, D.; Ludwig, H.
Bibcode: 2020AAS...23613002D
Altcode:
  High-precision spectroscopy might find 'truly' Earth-like
  exoplanets. Instrumental precisions are close to being achieved
  but limitations arise in the complexities of spectral-line
  formation. Spectral lines become somewhat asymmetric by being
  formed in dynamic gas flows. Radial-velocity signatures differ
  between different types of lines, change between stars, vary across
  stellar disks, and are modulated by magnetic activity. Spectroscopy
  across spatially resolved stellar disks has become possible by using
  transiting exoplanets as occulting spatial probes, permitting to
  test center-to-limb atmospheric hydrodynamics in stars also other
  than the Sun. Additional suitable target stars will likely be found
  in exoplanet surveys, and simulated observations are in progress to
  identify strategies for their near-future observations. From a grid
  of 3-D hydrodynamic CO5BOLD model atmospheres for solar-type stars,
  synthetic spectra have been computed at hyper-high spectral resolution
  (R greater than 1 million), for several center-to-limb locations across
  stellar disks. (The term 'hyper-high' is used since 'ultra-high'
  is already taken for lower-resolution data.) Such resolutions are
  required to fully resolve intrinsic line asymmetries. To segregate
  those from such arising due to blends, and also to obtain absolute
  wavelength shifts irrespective of errors in laboratory wavelengths,
  3-D spectra are matched against similar data from 1-D models. There,
  unblended lines appear symmetric at their laboratory wavelength
  positions, and differences to 3-D profiles isolate effects arising in
  the dynamic photospheres. Synthetic spectra are surveyed for unblended
  lines with different strengths, excitation potentials, and ionization
  levels, each of which contribute characteristic signatures of line
  asymmetries and apparent Doppler shifts. The hyper-high resolution
  data are degraded to common spectrometer values to appreciate what
  signatures may realistically be observed. An adequate understanding
  of both line formation and of spectrometer performance should enable
  to disentangle effects from variable stellar atmospheres from those
  induced by even small Earth-like exoplanets.

Title: State of the Profession: Intensity Interferometry
Authors: Kieda, David; Anton, Gisela; Barbano, Anastasia; Benbow,
   Wystan; Carlile, Colin; Daniel, Michael; Dravins, Dainis; Griffin,
   Sean; Hassan, Tarek; Holder, Jamie; LeBohec, Stephan; Matthews, Nolan;
   Montaruli, Theresa; Produit, Nicolas; Reynolds, Josh; Walter, Roland;
   Zampieri, Luca
Bibcode: 2019BAAS...51g.227K
Altcode: 2019astro2020U.227K; 2019arXiv190713181K
  This paper describes validation tests of Stellar Intensity
  Interferometry (SII) in the laboratory and SII measurements on nearby
  stars that have been completed as a technology demonstrator. The
  paper describes current and future observatories that will advance
  the impact and increase the instrumental resolution of SII during the
  upcoming decade.

Title: Science opportunities enabled by the era of Visible Band
    Stellar Imaging with sub-100 {\mu}arc-sec angular resolution
Authors: Kieda, D.; Acosta, Monica; Barbano, Anastasia; Carlile,
   Colin; Daniel, Michael; Dravins, Dainis; Holder, Jamie; Matthews,
   Nolan; Montaruli, Teresa; Walter, Roland; Zampieri, Luca
Bibcode: 2019arXiv190803164K
Altcode:
  This white paper briefly summarizes stellar science opportunities
  enabled by ultra-high resolution (sub-100 {\mu} arc-sec) astronomical
  imaging in the visible (U/V) wavebands. Next generation arrays of
  Imaging Cherenkov telescopes, to be constructed in the next decade,
  can provide unprecedented visible band imaging of several thousand
  bright (m&lt; 6), hot (O/B/A) stars using a modern implementation of
  Stellar Intensity Interferometry (SII). This white paper describes the
  astrophysics/astronomy science opportunities that may be uncovered in
  this new observation space during the next decade.

Title: Science opportunities enabled by the era of Visible Band
    Stellar Imaging with sub-100 μarc-sec angular resolution.
Authors: Kieda, David; Acosta, Monica; Barbano, Anastasia; Carlile,
   Colin; Daniel, Michael; Dravins, Dainis; Holder, Jamie; Matthews,
   Nolan; Montaruli, Teresa; Walter, Roland; Zampieri, Luca
Bibcode: 2019BAAS...51c.275K
Altcode: 2019astro2020T.275K
  This white paper briefly summarizes stellar science opportunities
  enabled by ultra-high resolution (sub-100 μarc-sec) astronomical
  imaging in the visible (U/V) wavebands. We describe the science impact
  of imaging of several thousand bright (m &lt; 6), hot (O/B/A) stars
  using a modern implementation of Stellar Intensity Interferometry (SII).

Title: Science with the Cherenkov Telescope Array
Authors: Cherenkov Telescope Array Consortium; Acharya, B. S.; Agudo,
   I.; Al Samarai, I.; Alfaro, R.; Alfaro, J.; Alispach, C.; Alves
   Batista, R.; Amans, J. -P.; Amato, E.; Ambrosi, G.; Antolini, E.;
   Antonelli, L. A.; Aramo, C.; Araya, M.; Armstrong, T.; Arqueros, F.;
   Arrabito, L.; Asano, K.; Ashley, M.; Backes, M.; Balazs, C.; Balbo, M.;
   Ballester, O.; Ballet, J.; Bamba, A.; Barkov, M.; Barres de Almeida,
   U.; Barrio, J. A.; Bastieri, D.; Becherini, Y.; Belfiore, A.; Benbow,
   W.; Berge, D.; Bernardini, E.; Bernardini, M. G.; Bernardos, M.;
   Bernlöhr, K.; Bertucci, B.; Biasuzzi, B.; Bigongiari, C.; Biland,
   A.; Bissaldi, E.; Biteau, J.; Blanch, O.; Blazek, J.; Boisson, C.;
   Bolmont, J.; Bonanno, G.; Bonardi, A.; Bonavolontà, C.; Bonnoli,
   G.; Bosnjak, Z.; Böttcher, M.; Braiding, C.; Bregeon, J.; Brill, A.;
   Brown, A. M.; Brun, P.; Brunetti, G.; Buanes, T.; Buckley, J.; Bugaev,
   V.; Bühler, R.; Bulgarelli, A.; Bulik, T.; Burton, M.; Burtovoi, A.;
   Busetto, G.; Canestrari, R.; Capalbi, M.; Capitanio, F.; Caproni, A.;
   Caraveo, P.; Cárdenas, V.; Carlile, C.; Carosi, R.; Carquín, E.;
   Carr, J.; Casanova, S.; Cascone, E.; Catalani, F.; Catalano, O.; Cauz,
   D.; Cerruti, M.; Chadwick, P.; Chaty, S.; Chaves, R. C. G.; Chen, A.;
   Chen, X.; Chernyakova, M.; Chikawa, M.; Christov, A.; Chudoba, J.;
   Cieślar, M.; Coco, V.; Colafrancesco, S.; Colin, P.; Conforti, V.;
   Connaughton, V.; Conrad, J.; Contreras, J. L.; Cortina, J.; Costa,
   A.; Costantini, H.; Cotter, G.; Covino, S.; Crocker, R.; Cuadra, J.;
   Cuevas, O.; Cumani, P.; D'Aì, A.; D'Ammando, F.; D'Avanzo, P.; D'Urso,
   D.; Daniel, M.; Davids, I.; Dawson, B.; Dazzi, F.; De Angelis, A.;
   de Cássia dos Anjos, R.; De Cesare, G.; De Franco, A.; de Gouveia
   Dal Pino, E. M.; de la Calle, I.; de los Reyes Lopez, R.; De Lotto,
   B.; De Luca, A.; De Lucia, M.; de Naurois, M.; de Oña Wilhelmi,
   E.; De Palma, F.; De Persio, F.; de Souza, V.; Deil, C.; Del Santo,
   M.; Delgado, C.; della Volpe, D.; Di Girolamo, T.; Di Pierro, F.;
   Di Venere, L.; Díaz, C.; Dib, C.; Diebold, S.; Djannati-Ataï, A.;
   Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Drass,
   H.; Dravins, D.; Dubus, G.; Dwarkadas, V. V.; Ebr, J.; Eckner, C.;
   Egberts, K.; Einecke, S.; Ekoume, T. R. N.; Elsässer, D.; Ernenwein,
   J. -P.; Espinoza, C.; Evoli, C.; Fairbairn, M.; Falceta-Goncalves,
   D.; Falcone, A.; Farnier, C.; Fasola, G.; Fedorova, E.; Fegan, S.;
   Fernandez-Alonso, M.; Fernández-Barral, A.; Ferrand, G.; Fesquet,
   M.; Filipovic, M.; Fioretti, V.; Fontaine, G.; Fornasa, M.; Fortson,
   L.; Freixas Coromina, L.; Fruck, C.; Fujita, Y.; Fukazawa, Y.; Funk,
   S.; Füßling, M.; Gabici, S.; Gadola, A.; Gallant, Y.; Garcia,
   B.; Garcia López, R.; Garczarczyk, M.; Gaskins, J.; Gasparetto,
   T.; Gaug, M.; Gerard, L.; Giavitto, G.; Giglietto, N.; Giommi, P.;
   Giordano, F.; Giro, E.; Giroletti, M.; Giuliani, A.; Glicenstein,
   J. -F.; Gnatyk, R.; Godinovic, N.; Goldoni, P.; Gómez-Vargas, G.;
   González, M. M.; González, J. M.; Götz, D.; Graham, J.; Grandi,
   P.; Granot, J.; Green, A. J.; Greenshaw, T.; Griffiths, S.; Gunji,
   S.; Hadasch, D.; Hara, S.; Hardcastle, M. J.; Hassan, T.; Hayashi,
   K.; Hayashida, M.; Heller, M.; Helo, J. C.; Hermann, G.; Hinton,
   J.; Hnatyk, B.; Hofmann, W.; Holder, J.; Horan, D.; Hörandel, J.;
   Horns, D.; Horvath, P.; Hovatta, T.; Hrabovsky, M.; Hrupec, D.;
   Humensky, T. B.; Hütten, M.; Iarlori, M.; Inada, T.; Inome, Y.;
   Inoue, S.; Inoue, T.; Inoue, Y.; Iocco, F.; Ioka, K.; Iori, M.;
   Ishio, K.; Iwamura, Y.; Jamrozy, M.; Janecek, P.; Jankowsky, D.;
   Jean, P.; Jung-Richardt, I.; Jurysek, J.; Kaaret, P.; Karkar, S.;
   Katagiri, H.; Katz, U.; Kawanaka, N.; Kazanas, D.; Khélifi, B.;
   Kieda, D. B.; Kimeswenger, S.; Kimura, S.; Kisaka, S.; Knapp, J.;
   Knödlseder, J.; Koch, B.; Kohri, K.; Komin, N.; Kosack, K.; Kraus,
   M.; Krause, M.; Krauß, F.; Kubo, H.; Kukec Mezek, G.; Kuroda, H.;
   Kushida, J.; La Palombara, N.; Lamanna, G.; Lang, R. G.; Lapington,
   J.; Le Blanc, O.; Leach, S.; Lees, J. -P.; Lefaucheur, J.; Leigui
   de Oliveira, M. A.; Lenain, J. -P.; Lico, R.; Limon, M.; Lindfors,
   E.; Lohse, T.; Lombardi, S.; Longo, F.; López, M.; López-Coto,
   R.; Lu, C. -C.; Lucarelli, F.; Luque-Escamilla, P. L.; Lyard, E.;
   Maccarone, M. C.; Maier, G.; Majumdar, P.; Malaguti, G.; Mandat, D.;
   Maneva, G.; Manganaro, M.; Mangano, S.; Marcowith, A.; Marín, J.;
   Markoff, S.; Martí, J.; Martin, P.; Martínez, M.; Martínez, G.;
   Masetti, N.; Masuda, S.; Maurin, G.; Maxted, N.; Mazin, D.; Medina,
   C.; Melandri, A.; Mereghetti, S.; Meyer, M.; Minaya, I. A.; Mirabal,
   N.; Mirzoyan, R.; Mitchell, A.; Mizuno, T.; Moderski, R.; Mohammed,
   M.; Mohrmann, L.; Montaruli, T.; Moralejo, A.; Morcuende-Parrilla,
   D.; Mori, K.; Morlino, G.; Morris, P.; Morselli, A.; Moulin, E.;
   Mukherjee, R.; Mundell, C.; Murach, T.; Muraishi, H.; Murase, K.;
   Nagai, A.; Nagataki, S.; Nagayoshi, T.; Naito, T.; Nakamori, T.;
   Nakamura, Y.; Niemiec, J.; Nieto, D.; Nikołajuk, M.; Nishijima, K.;
   Noda, K.; Nosek, D.; Novosyadlyj, B.; Nozaki, S.; O'Brien, P.; Oakes,
   L.; Ohira, Y.; Ohishi, M.; Ohm, S.; Okazaki, N.; Okumura, A.; Ong,
   R. A.; Orienti, M.; Orito, R.; Osborne, J. P.; Ostrowski, M.; Otte,
   N.; Oya, I.; Padovani, M.; Paizis, A.; Palatiello, M.; Palatka, M.;
   Paoletti, R.; Paredes, J. M.; Pareschi, G.; Parsons, R. D.; Pe'er,
   A.; Pech, M.; Pedaletti, G.; Perri, M.; Persic, M.; Petrashyk, A.;
   Petrucci, P.; Petruk, O.; Peyaud, B.; Pfeifer, M.; Piano, G.; Pisarski,
   A.; Pita, S.; Pohl, M.; Polo, M.; Pozo, D.; Prandini, E.; Prast, J.;
   Principe, G.; Prokhorov, D.; Prokoph, H.; Prouza, M.; Pühlhofer, G.;
   Punch, M.; Pürckhauer, S.; Queiroz, F.; Quirrenbach, A.; Rainò,
   S.; Razzaque, S.; Reimer, O.; Reimer, A.; Reisenegger, A.; Renaud,
   M.; Rezaeian, A. H.; Rhode, W.; Ribeiro, D.; Ribó, M.; Richtler, T.;
   Rico, J.; Rieger, F.; Riquelme, M.; Rivoire, S.; Rizi, V.; Rodriguez,
   J.; Rodriguez Fernandez, G.; Rodríguez Vázquez, J. J.; Rojas, G.;
   Romano, P.; Romeo, G.; Rosado, J.; Rovero, A. C.; Rowell, G.; Rudak,
   B.; Rugliancich, A.; Rulten, C.; Sadeh, I.; Safi-Harb, S.; Saito, T.;
   Sakaki, N.; Sakurai, S.; Salina, G.; Sánchez-Conde, M.; Sandaker,
   H.; Sandoval, A.; Sangiorgi, P.; Sanguillon, M.; Sano, H.; Santander,
   M.; Sarkar, S.; Satalecka, K.; Saturni, F. G.; Schioppa, E. J.;
   Schlenstedt, S.; Schneider, M.; Schoorlemmer, H.; Schovanek, P.;
   Schulz, A.; Schussler, F.; Schwanke, U.; Sciacca, E.; Scuderi, S.;
   Seitenzahl, I.; Semikoz, D.; Sergijenko, O.; Servillat, M.; Shalchi,
   A.; Shellard, R. C.; Sidoli, L.; Siejkowski, H.; Sillanpää, A.;
   Sironi, G.; Sitarek, J.; Sliusar, V.; Slowikowska, A.; Sol, H.;
   Stamerra, A.; Stanič, S.; Starling, R.; Stawarz, Ł.; Stefanik, S.;
   Stephan, M.; Stolarczyk, T.; Stratta, G.; Straumann, U.; Suomijarvi,
   T.; Supanitsky, A. D.; Tagliaferri, G.; Tajima, H.; Tavani, M.;
   Tavecchio, F.; Tavernet, J. -P.; Tayabaly, K.; Tejedor, L. A.;
   Temnikov, P.; Terada, Y.; Terrier, R.; Terzic, T.; Teshima, M.;
   Testa, V.; Thoudam, S.; Tian, W.; Tibaldo, L.; Tluczykont, M.; Todero
   Peixoto, C. J.; Tokanai, F.; Tomastik, J.; Tonev, D.; Tornikoski,
   M.; Torres, D. F.; Torresi, E.; Tosti, G.; Tothill, N.; Tovmassian,
   G.; Travnicek, P.; Trichard, C.; Trifoglio, M.; Troyano Pujadas, I.;
   Tsujimoto, S.; Umana, G.; Vagelli, V.; Vagnetti, F.; Valentino, M.;
   Vallania, P.; Valore, L.; van Eldik, C.; Vandenbroucke, J.; Varner,
   G. S.; Vasileiadis, G.; Vassiliev, V.; Vázquez Acosta, M.; Vecchi,
   M.; Vega, A.; Vercellone, S.; Veres, P.; Vergani, S.; Verzi, V.;
   Vettolani, G. P.; Viana, A.; Vigorito, C.; Villanueva, J.; Voelk,
   H.; Vollhardt, A.; Vorobiov, S.; Vrastil, M.; Vuillaume, T.; Wagner,
   S. J.; Wagner, R.; Walter, R.; Ward, J. E.; Warren, D.; Watson,
   J. J.; Werner, F.; White, M.; White, R.; Wierzcholska, A.; Wilcox,
   P.; Will, M.; Williams, D. A.; Wischnewski, R.; Wood, M.; Yamamoto,
   T.; Yamazaki, R.; Yanagita, S.; Yang, L.; Yoshida, T.; Yoshiike, S.;
   Yoshikoshi, T.; Zacharias, M.; Zaharijas, G.; Zampieri, L.; Zandanel,
   F.; Zanin, R.; Zavrtanik, M.; Zavrtanik, D.; Zdziarski, A. A.; Zech,
   A.; Zechlin, H.; Zhdanov, V. I.; Ziegler, A.; Zorn, J.
Bibcode: 2019scta.book.....C
Altcode: 2017arXiv170907997C
  The Cherenkov Telescope Array, CTA, will be the major global
  observatory for very high energy gamma-ray astronomy over the next
  decade and beyond. The scientific potential of CTA is extremely broad:
  from understanding the role of relativistic cosmic particles to the
  search for dark matter. CTA is an explorer of the extreme universe,
  probing environments from the immediate neighbourhood of black holes to
  cosmic voids on the largest scales. Covering a huge range in photon
  energy from 20 GeV to 300 TeV, CTA will improve on all aspects of
  performance with respect to current instruments. The observatory
  will operate arrays on sites in both hemispheres to provide full sky
  coverage and will hence maximize the potential for the rarest phenomena
  such as very nearby supernovae, gamma-ray bursts or gravitational
  wave transients. With 99 telescopes on the southern site and 19
  telescopes on the northern site, flexible operation will be possible,
  with sub-arrays available for specific tasks. CTA will have important
  synergies with many of the new generation of major astronomical and
  astroparticle observatories. Multi-wavelength and multi-messenger
  approaches combining CTA data with those from other instruments will
  lead to a deeper understanding of the broad-band non-thermal properties
  of target sources. The CTA Observatory will be operated as an open,
  proposal-driven observatory, with all data available on a public archive
  after a pre-defined proprietary period. Scientists from institutions
  worldwide have combined together to form the CTA Consortium. This
  Consortium has prepared a proposal for a Core Programme of highly
  motivated observations. The programme, encompassing approximately
  40% of the available observing time over the first ten years of CTA
  operation, is made up of individual Key Science Projects (KSPs),
  which are presented in this document.

Title: Capabilities beyond Gamma Rays
Authors: Bühler, R.; Dravins, D.; Egberts, K.; Hinton, J. A.; Parsons,
   R. D.; Cherenkov Telescope Array Consortium
Bibcode: 2019scta.book..291B
Altcode:
  Although designed as a gamma-ray observatory, CTA is a powerful tool
  for a range of other astrophysics and astroparticle physics. For
  example, CTA can make precision studies of charged cosmic rays in
  the energy range from ∼100 GeV up to PeV energies, and it can
  be used as an instrument for optical intensity interferometry, to
  provide unprecedented angular resolution in the optical for bright
  sources. Below, we briefly summarise these possibilities. Most of
  the topics we discuss can be explored in parallel with gamma-ray
  data-taking, without interfering with the major science operations of
  CTA. Those studies (such as intensity interferometry) which require
  specific observations can likely make use of bright moonlight time,
  thus enhancing the CTA science return without negative impact on the
  key science goals.

Title: Spatially resolved spectroscopy across stellar
    surfaces. III. Photospheric Fe I lines across HD 189733A (K1 V)
Authors: Dravins, Dainis; Gustavsson, Martin; Ludwig, Hans-Günter
Bibcode: 2018A&A...616A.144D
Altcode: 2018arXiv180600012D
  Context. Spectroscopy across spatially resolved stellar surfaces reveals
  spectral line profiles free from rotational broadening, whose gradual
  changes from disk center toward the stellar limb reflect an atmospheric
  fine structure that is possible to model by 3D hydrodynamics. <BR />
  Aims: Previous studies of photospheric spectral lines across stellar
  disks exist for the Sun and <ASTROBJ>HD 209458</ASTROBJ> (G0 V) and
  are now extended to the planet-hosting <ASTROBJ>HD 189733A</ASTROBJ>
  to sample a cooler K-type star and explore the future potential of
  the method. <BR /> Methods: During exoplanet transit, stellar surface
  portions successively become hidden and differential spectroscopy
  between various transit phases uncovers spectra of small surface
  segments temporarily hidden behind the planet. The method was elaborated
  in Paper I, in which observable signatures were predicted quantitatively
  from hydrodynamic simulations. <BR /> Results: From observations of
  <ASTROBJ>HD 189733A</ASTROBJ> with the ESO HARPS spectrometer at
  λ/Δλ 115 000, profiles for stronger and weaker Fe I lines are
  retrieved at several center-to-limb positions, reaching adequate
  S/N after averaging over numerous similar lines. <BR /> Conclusions:
  Retrieved line profile widths and depths are compared to synthetic
  ones from models with parameters bracketing those of the target star
  and are found to be consistent with 3D simulations. Center-to-limb
  changes strongly depend on the surface granulation structure and much
  greater line-width variation is predicted in hotter F-type stars
  with vigorous granulation than in cooler K-types. Such parameters,
  obtained from fits to full line profiles, are realistic to retrieve
  for brighter planet-hosting stars, while their hydrodynamic modeling
  offers previously unexplored diagnostics for stellar atmospheric fine
  structure and 3D line formation. Precise modeling may be required in
  searches for Earth-analog exoplanets around K-type stars, whose more
  tranquil surface granulation and lower ensuing microvariability may
  enable such detections.

Title: Intensity Interferometry: Imaging Stars with Kilometer
    Baselines
Authors: Dravins, Dainis
Bibcode: 2018iss..confE...6D
Altcode:
  Microarcsecond imaging will reveal stellar surfaces but requires
  kilometer-scale interferometers. Intensity interferometry circumvents
  atmospheric turbulence by correlating intensity fluctuations between
  independent telescopes. Telescopes connect only electronically,
  and the error budget relates to electronic timescales of nanoseconds
  (light-travel distances on the order of a meter), enabling the use of
  imperfect optics in a turbulent atmosphere. Once pioneered by Hanbury
  Brown and Twiss, digital versions have now been demonstrated in the
  laboratory, reconstructing diffraction-limited images from hundreds
  of optical baselines. Arrays of Cherenkov telescopes (primarily
  erected for gamma-ray studies) will extend over a few km, enabling
  an optical equivalent of radio interferometers. Resolutions in the
  tens of microarcseconds will resolve rotationally flattened stars with
  their circumstellar disks and winds, or possibly even the silhouettes
  of transiting exoplanets. Applying the method to mirror segments in
  extremely large telescopes (even with an incompletely filled main
  mirror, poor seeing, no adaptive optics), the diffraction limit in
  the blue may be reached.

Title: Seeing Stars - Intensity Interferometry in the Laboratory &amp;
    on the Ground
Authors: Carlile, Colin; Dravins, Dainis
Bibcode: 2018iss..confE...3C
Altcode:
  In many ways it is a golden age for astronomy. Spectacular new
  discoveries, for example the detection of gravitational waves, are
  very dependent upon instrumental development. The specific instrument
  development we propose, Intensity Interferometry (II), aims toimprove
  the spatial resolution of optical telescopes by 100x to 50µas [1]. This
  is impractical to achieve by increasing the size of telescopes or by
  extending the capabilities of phase interferometry. II, if implemented
  on the Cherenkov Telescope Array (CTA) currently being installed in La
  Palma and Paranal, would record the light intensity - the photon train
  - from many different telescopes, up to 2 km apart, on a nanosecond
  timescale and compare them. The signal from the many pairs of telescopes
  would quantify the degree of correlation by extracting the second-order
  correlation function, and thus create an image. This is not a real space
  image. However we can invert the data by Fourier Transform and create a
  real image. The more telescopes, the better resolved and more physical
  is the image, enabling the study of sunspots on nearby stars; orbiting
  binary stars; or exoplanets traversing the disc of their own star. We
  understand the Sun well but we have little experimental knowledge of
  how representative it is of main sequence stars. To test the II method,
  at Lund Observatory we have set up a laboratory analogue comprising ten
  small telescopes observing an artificial star created by light from a
  laser. The method has been shown to work [2] and the telescope array
  has now been extended to two dimensions. We are in discussion with
  other groups to explore the possibility of implementing this method
  on real telescopes observing actual stars. We plan to do this with
  the prototype Small Size Telescopes being built by groups in Europe,
  and ultimately with the CTA itself. A Science Working Group for II has
  now been set up within the CTA Consortium, of which Lund University is
  an integral part. A Letter of Intent has been sent to CTA expressing
  these intentions. An attractive aspect of II is its complementarity to
  the principle goal of CTA - the exploration of high energy cosmic rays
  via the Cherenkov light they generate in the atmosphere. This can only
  be observed under the most demanding atmospheric conditions whereas II
  can be recorded when conditions are poor: with a bright Moon, during
  periods of turbulence; in hazy conditions; or after dusk and before
  dawn. Two further advantages of implementing an II option on CTA are the
  minimal marginal costs incurred to an already 400M€ investment and,
  secondly, that even a few telescopes would produce unique scientific
  results even in the early days when the CTA array is far from
  complete. [1] Dainis Dravins and Colin Carlile, SPIE Newsroom (2016),
  http://spie.org/newsroom/6504-kilometer-baseline-optical-intensity-interferometry-for-stellar-surface-observations
  [2] D. Dravins, T. Lagadec, P.D. Nuñez, Nature Communications 6, 6852
  (2015)

Title: Revealing Stellar Surface Structure Behind Transiting
    Exoplanets
Authors: Dravins, Dainis
Bibcode: 2018iss..confE...7D
Altcode:
  During exoplanet transits, successive stellar surface portions become
  hidden and differential spectroscopy between various transit phases
  provide spectra of small surface segments temporarily hidden behind the
  planet. Line profile changes across the stellar disk offer diagnostics
  for hydrodynamic modeling, while exoplanet analyses require stellar
  background spectra to be known along the transit path. Since even
  giant planets cover only a small fraction of any main-sequence star,
  very precise observations are required, as well as averaging over
  numerous spectral lines with similar parameters. Spatially resolved
  Fe I line profiles across stellar disks have now been retrieved for
  HD209458 (G0V) and HD189733A (K1V), using data from the UVES and HARPS
  spectrometers. Free from rotational broadening, spatially resolved
  profiles are narrower and deeper than in integrated starlight. During
  transit, the profiles shift towards longer wavelengths, illustrating
  both stellar rotation at the latitude of transit and the prograde
  orbital motion of the exoplanets. This method will soon become
  applicable to more stars, once additional bright exoplanet hosts have
  been found.

Title: Stellar atmospheres behind transiting exoplanets
Authors: Dravins, D.; Ludwig, H. -G.; Dahlén, E.; Gustavsson, M.;
   Pazira, H.
Bibcode: 2017EPSC...11...21D
Altcode:
  Stellar surfaces are covered with brighter and darker structures, just
  like on the Sun. While solar surface details can be easily studied
  with telescopes, stellar surfaces cannot thus be resolved. However,
  one can use planets that happen to pass in front of distant stars as
  "shades" that successively block out small portions of the stellar
  surface behind. By measuring how the light from the star changes during
  such a transit, one can deduce stellar surface properties. Knowing those
  is required not only to study the star as such, but also to deduce the
  chemical composition of the planet that is passing in front of it,
  where some of the detected starlight has been filtered through the
  planet's atmosphere.

Title: Cherenkov Telescope Array Contributions to the 35th
    International Cosmic Ray Conference (ICRC2017)
Authors: Acero, F.; Acharya, B. S.; Acín Portella, V.; Adams, C.;
   Agudo, I.; Aharonian, F.; Samarai, I. Al; Alberdi, A.; Alcubierre,
   M.; Alfaro, R.; Alfaro, J.; Alispach, C.; Aloisio, R.; Alves Batista,
   R.; Amans, J. -P.; Amato, E.; Ambrogi, L.; Ambrosi, G.; Ambrosio, M.;
   Anderson, J.; Anduze, M.; Angüner, E. O.; Antolini, E.; Antonelli,
   L. A.; Antonuccio, V.; Antoranz, P.; Aramo, C.; Araya, M.; Arcaro, C.;
   Armstrong, T.; Arqueros, F.; Arrabito, L.; Arrieta, M.; Asano, K.;
   Asano, A.; Ashley, M.; Aubert, P.; Singh, C. B.; Babic, A.; Backes,
   M.; Bajtlik, S.; Balazs, C.; Balbo, M.; Ballester, O.; Ballet, J.;
   Ballo, L.; Balzer, A.; Bamba, A.; Bandiera, R.; Barai, P.; Barbier,
   C.; Barcelo, M.; Barkov, M.; Barres de Almeida, U.; Barrio, J. A.;
   Bastieri, D.; Bauer, C.; Becciani, U.; Becherini, Y.; Becker Tjus,
   J.; Bednarek, W.; Belfiore, A.; Benbow, W.; Benito, M.; Berge, D.;
   Bernardini, E.; Bernardini, M. G.; Bernardos, M.; Bernhard, S.;
   Bernlöhr, K.; Bertinelli Salucci, C.; Bertucci, B.; Besel, M. -A.;
   Beshley, V.; Bettane, J.; Bhatt, N.; Bhattacharyya, W.; Bhattachryya,
   S.; Biasuzzi, B.; Bicknell, G.; Bigongiari, C.; Biland, A.; Bilinsky,
   A.; Bird, R.; Bissaldi, E.; Biteau, J.; Bitossi, M.; Blanch, O.;
   Blasi, P.; Blazek, J.; Boccato, C.; Bockermann, C.; Boehm, C.;
   Bohacova, M.; Boisson, C.; Bolmont, J.; Bonanno, G.; Bonardi, A.;
   Bonavolontà, C.; Bonnoli, G.; Borkowski, J.; Bose, R.; Bosnjak,
   Z.; Böttcher, M.; Boutonnet, C.; Bouyjou, F.; Bowman, L.; Bozhilov,
   V.; Braiding, C.; Brau-Nogué, S.; Bregeon, J.; Briggs, M.; Brill,
   A.; Brisken, W.; Bristow, D.; Britto, R.; Brocato, E.; Brown, A. M.;
   Brown, S.; Brügge, K.; Brun, P.; Brun, P.; Brun, F.; Brunetti, L.;
   Brunetti, G.; Bruno, P.; Bryan, M.; Buckley, J.; Bugaev, V.; Bühler,
   R.; Bulgarelli, A.; Bulik, T.; Burton, M.; Burtovoi, A.; Busetto, G.;
   Buson, S.; Buss, J.; Byrum, K.; Caccianiga, A.; Cameron, R.; Canelli,
   F.; Canestrari, R.; Capalbi, M.; Capasso, M.; Capitanio, F.; Caproni,
   A.; Capuzzo-Dolcetta, R.; Caraveo, P.; Cárdenas, V.; Cardenzana,
   J.; Cardillo, M.; Carlile, C.; Caroff, S.; Carosi, R.; Carosi, A.;
   Carquín, E.; Carr, J.; Casandjian, J. -M.; Casanova, S.; Cascone, E.;
   Castro-Tirado, A. J.; Castroviejo Mora, J.; Catalani, F.; Catalano, O.;
   Cauz, D.; Celestino Silva, C.; Celli, S.; Cerruti, M.; Chabanne, E.;
   Chadwick, P.; Chakraborty, N.; Champion, C.; Chatterjee, A.; Chaty, S.;
   Chaves, R.; Chen, A.; Chen, X.; Cheng, K.; Chernyakova, M.; Chikawa,
   M.; Chitnis, V. R.; Christov, A.; Chudoba, J.; Cieślar, M.; Clark,
   P.; Coco, V.; Colafrancesco, S.; Colin, P.; Colombo, E.; Colome, J.;
   Colonges, S.; Conforti, V.; Connaughton, V.; Conrad, J.; Contreras,
   J. L.; Cornat, R.; Cortina, J.; Costa, A.; Costantini, H.; Cotter, G.;
   Courty, B.; Covino, S.; Covone, G.; Cristofari, P.; Criswell, S. J.;
   Crocker, R.; Croston, J.; Crovari, C.; Cuadra, J.; Cuevas, O.; Cui,
   X.; Cumani, P.; Cusumano, G.; D'Aì, A.; D'Ammando, F.; D'Avanzo,
   P.; D'Urso, D.; Da Vela, P.; Dale, Ø.; Dang, V. T.; Dangeon, L.;
   Daniel, M.; Davids, I.; Dawson, B.; Dazzi, F.; De Angelis, A.; De
   Caprio, V.; de Cássia dos Anjos, R.; De Cesare, G.; De Franco, A.;
   De Frondat, F.; de Gouveia Dal Pino, E. M.; de la Calle, I.; De Lisio,
   C.; de los Reyes Lopez, R.; De Lotto, B.; De Luca, A.; De Lucia, M.;
   de Mello Neto, J. R. T.; de Naurois, M.; de Oña Wilhelmi, E.; De
   Palma, F.; De Persio, F.; de Souza, V.; Decock, J.; Deil, C.; Deiml,
   P.; Del Santo, M.; Delagnes, E.; Deleglise, G.; Delfino Reznicek, M.;
   Delgado, C.; Delgado Mengual, J.; Della Ceca, R.; della Volpe, D.;
   Detournay, M.; Devin, J.; Di Girolamo, T.; Di Giulio, C.; Di Pierro,
   F.; Di Venere, L.; Diaz, L.; Díaz, C.; Dib, C.; Dickinson, H.;
   Diebold, S.; Digel, S.; Djannati-Ataï, A.; Doert, M.; Domínguez,
   A.; Dominis Prester, D.; Donnarumma, I.; Dorner, D.; Doro, M.;
   Dournaux, J. -L.; Downes, T.; Drake, G.; Drappeau, S.; Drass, H.;
   Dravins, D.; Drury, L.; Dubus, G.; Dundas Morå, K.; Durkalec, A.;
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   S.; Eisch, J.; Eisenkolb, F.; Ekoume, T. R. N.; Eleftheriadis, C.;
   Elsässer, D.; Emmanoulopoulos, D.; Ernenwein, J. -P.; Escarate,
   P.; Eschbach, S.; Espinoza, C.; Evans, P.; Evoli, C.; Fairbairn, M.;
   Falceta-Goncalves, D.; Falcone, A.; Fallah Ramazani, V.; Farakos, K.;
   Farrell, E.; Fasola, G.; Favre, Y.; Fede, E.; Fedora, R.; Fedorova,
   E.; Fegan, S.; Fernandez-Alonso, M.; Fernández-Barral, A.; Ferrand,
   G.; Ferreira, O.; Fesquet, M.; Fiandrini, E.; Fiasson, A.; Filipovic,
   M.; Fink, D.; Finley, J. P.; Finley, C.; Finoguenov, A.; Fioretti,
   V.; Fiorini, M.; Flores, H.; Foffano, L.; Föhr, C.; Fonseca, M. V.;
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   N.; Fraga, B.; Franco, F. J.; Freixas Coromina, L.; Fruck, C.; Fugazza,
   D.; Fujita, Y.; Fukami, S.; Fukazawa, Y.; Fukui, Y.; Funk, S.; Furniss,
   A.; Füßling, M.; Gabici, S.; Gadola, A.; Gallant, Y.; Galloway, D.;
   Gallozzi, S.; Garcia, B.; Garcia, A.; García Gil, R.; Garcia López,
   R.; Garczarczyk, M.; Gardiol, D.; Gargano, F.; Gargano, C.; Garozzo,
   S.; Garrido-Ruiz, M.; Gascon, D.; Gasparetto, T.; Gaté, F.; Gaug,
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   A.; Ghedina, A.; Ghirlanda, G.; Giammaria, P.; Gianotti, F.; Giebels,
   B.; Giglietto, N.; Gika, V.; Gimenes, R.; Giommi, P.; Giordano, F.;
   Giovannini, G.; Giro, E.; Giroletti, M.; Gironnet, J.; Giuliani, A.;
   Glicenstein, J. -F.; Gnatyk, R.; Godinovic, N.; Goldoni, P.; Gómez,
   J. L.; Gómez-Vargas, G.; González, M. M.; González, J. M.; Gothe,
   K. S.; Gotz, D.; Goullon, J.; Grabarczyk, T.; Graciani, R.; Graham,
   J.; Grandi, P.; Granot, J.; Grasseau, G.; Gredig, R.; Green, A. J.;
   Greenshaw, T.; Grenier, I.; Griffiths, S.; Grillo, A.; Grondin, M. -H.;
   Grube, J.; Guarino, V.; Guest, B.; Gueta, O.; Gunji, S.; Gyuk, G.;
   Hadasch, D.; Hagge, L.; Hahn, J.; Hahn, A.; Hakobyan, H.; Hara, S.;
   Hardcastle, M. J.; Hassan, T.; Haubold, T.; Haupt, A.; Hayashi, K.;
   Hayashida, M.; He, H.; Heller, M.; Helo, J. C.; Henault, F.; Henri, G.;
   Hermann, G.; Hermel, R.; Herrera Llorente, J.; Herrero, A.; Hervet, O.;
   Hidaka, N.; Hinton, J.; Hiroshima, N.; Hirotani, K.; Hnatyk, B.; Hoang,
   J. K.; Hoffmann, D.; Hofmann, W.; Holder, J.; Horan, D.; Hörandel,
   J.; Hörbe, M.; Horns, D.; Horvath, P.; Houles, J.; Hovatta, T.;
   Hrabovsky, M.; Hrupec, D.; Huet, J. -M.; Hughes, G.; Hui, D.; Hull,
   G.; Humensky, T. B.; Hussein, M.; Hütten, M.; Iarlori, M.; Ikeno,
   Y.; Illa, J. M.; Impiombato, D.; Inada, T.; Ingallinera, A.; Inome,
   Y.; Inoue, S.; Inoue, T.; Inoue, Y.; Iocco, F.; Ioka, K.; Ionica,
   M.; Iori, M.; Iriarte, A.; Ishio, K.; Israel, G. L.; Iwamura, Y.;
   Jablonski, C.; Jacholkowska, A.; Jacquemier, J.; Jamrozy, M.; Janecek,
   P.; Jankowsky, F.; Jankowsky, D.; Jansweijer, P.; Jarnot, C.; Jean, P.;
   Johnson, C. A.; Josselin, M.; Jung-Richardt, I.; Jurysek, J.; Kaaret,
   P.; Kachru, P.; Kagaya, M.; Kakuwa, J.; Kalekin, O.; Kankanyan, R.;
   Karastergiou, A.; Karczewski, M.; Karkar, S.; Katagiri, H.; Kataoka,
   J.; Katarzyński, K.; Katz, U.; Kawanaka, N.; Kaye, L.; Kazanas, D.;
   Kelley-Hoskins, N.; Khélifi, B.; Kieda, D. B.; Kihm, T.; Kimeswenger,
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   G.; Lahmann, R.; Lalik, K.; Lamanna, G.; Landoni, M.; Landriu, D.;
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   T.; Louis, F.; Louys, M.; Lucarelli, F.; Lucchesi, D.; Luque-Escamilla,
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   Vagnetti, F.; Valentino, M.; Vallania, P.; Valore, L.; Van den Berg,
   A. M.; van Driel, W.; van Eldik, C.; van Soelen, B.; Vandenbroucke,
   J.; Vanderwalt, J.; Varner, G. S.; Vasileiadis, G.; Vassiliev, V.;
   Vázquez, J. R.; Vázquez Acosta, M.; Vecchi, M.; Vega, A.; Veitch,
   P.; Venault, P.; Venter, C.; Vercellone, S.; Veres, P.; Vergani,
   S.; Verzi, V.; Vettolani, G. P.; Veyssiere, C.; Viana, A.; Vicha,
   J.; Vigorito, C.; Villanueva, J.; Vincent, P.; Vink, J.; Visconti,
   F.; Vittorini, V.; Voelk, H.; Voisin, V.; Vollhardt, A.; Vorobiov,
   S.; Vovk, I.; Vrastil, M.; Vuillaume, T.; Wagner, S. J.; Wagner, R.;
   Wagner, P.; Wakely, S. P.; Walstra, T.; Walter, R.; Ward, M.; Ward,
   J. E.; Warren, D.; Watson, J. J.; Webb, N.; Wegner, P.; Weiner, O.;
   Weinstein, A.; Weniger, C.; Werner, F.; Wetteskind, H.; White, M.;
   White, R.; Wierzcholska, A.; Wiesand, S.; Wijers, R.; Wilcox, P.;
   Wilhelm, A.; Wilkinson, M.; Will, M.; Williams, D. A.; Winter, M.;
   Wojcik, P.; Wolf, D.; Wood, M.; Wörnlein, A.; Wu, T.; Yadav, K. K.;
   Yaguna, C.; Yamamoto, T.; Yamamoto, H.; Yamane, N.; Yamazaki, R.;
   Yanagita, S.; Yang, L.; Yelos, D.; Yoshida, T.; Yoshida, M.; Yoshiike,
   S.; Yoshikoshi, T.; Yu, P.; Zaborov, D.; Zacharias, M.; Zaharijas, G.;
   Zajczyk, A.; Zampieri, L.; Zandanel, F.; Zanin, R.; Zanmar Sanchez,
   R.; Zaric, D.; Zavrtanik, M.; Zavrtanik, D.; Zdziarski, A. A.; Zech,
   A.; Zechlin, H.; Zhdanov, V. I.; Ziegler, A.; Ziemann, J.; Ziętara,
   K.; Zink, A.; Ziółkowski, J.; Zitelli, V.; Zoli, A.; Zorn, J.
Bibcode: 2017arXiv170903483A
Altcode: 2017arXiv170903483C
  List of contributions from the Cherenkov Telescope Array Consortium
  presented at the 35th International Cosmic Ray Conference, July 12-20
  2017, Busan, Korea.

Title: Spatially resolved spectroscopy across stellar
    surfaces. II. High-resolution spectra across HD 209458 (G0 V)
Authors: Dravins, Dainis; Ludwig, Hans-Günter; Dahlén, Erik;
   Pazira, Hiva
Bibcode: 2017A&A...605A..91D
Altcode: 2017arXiv170801618D
  Context. High-resolution spectroscopy across spatially resolved
  stellar surfaces aims at obtaining spectral-line profiles that
  are free from rotational broadening; the gradual changes of these
  profiles from disk center toward the stellar limb reveal properties
  of atmospheric fine structure, which are possible to model with 3D
  hydrodynamics. <BR /> Aims: Previous such studies have only been
  carried out for the Sun but are now extended to other stars. In this
  work, profiles of photospheric spectral lines are retrieved across
  the disk of the planet-hosting star HD 209458 (G0 V). <BR /> Methods:
  During exoplanet transit, stellar surface portions successively become
  hidden and differential spectroscopy provides spectra of small surface
  segments temporarily hidden behind the planet. The method was elaborated
  in Paper I, with observable signatures quantitatively predicted from
  hydrodynamic simulations. <BR /> Results: From observations of HD
  209458 with spectral resolution λ/ Δλ 80 000, photospheric Fe
  I line profiles are obtained at several center-to-limb positions,
  reaching adequately high S/N after averaging over numerous similar
  lines. <BR /> Conclusions: Retrieved line profiles are compared
  to synthetic line profiles. Hydrodynamic 3D models predict, and
  current observations confirm, that photospheric absorption lines
  become broader and shallower toward the stellar limb, reflecting that
  horizontal velocities in stellar granulation are greater than vertical
  velocities. Additional types of 3D signatures will become observable
  with the highest resolution spectrometers at large telescopes.

Title: Spatially resolved spectroscopy across stellar
    surfaces. I. Using exoplanet transits to analyze 3D stellar
    atmospheres
Authors: Dravins, Dainis; Ludwig, Hans-Günter; Dahlén, Erik;
   Pazira, Hiva
Bibcode: 2017A&A...605A..90D
Altcode: 2017arXiv170801616D
  Context. High-precision stellar analyses require hydrodynamic modeling
  to interpret chemical abundances or oscillation modes. Exoplanet
  atmosphere studies require stellar background spectra to be known
  along the transit path while detection of Earth analogs require
  stellar microvariability to be understood. Hydrodynamic 3D models can
  be computed for widely different stars but have been tested in detail
  only for the Sun with its resolved surface features. Model predictions
  include spectral line shapes, asymmetries, and wavelength shifts,
  and their center-to-limb changes across stellar disks. <BR /> Aims: We
  observe high-resolution spectral line profiles across spatially highly
  resolved stellar surfaces, which are free from the effects of spatial
  smearing and rotational broadening present in full-disk spectra,
  enabling comparisons to synthetic profiles from 3D models. <BR />
  Methods: During exoplanet transits, successive stellar surface portions
  become hidden and differential spectroscopy between various transit
  phases provides spectra of small surface segments temporarily hidden
  behind the planet. Planets cover no more than 1% of any main-sequence
  star, enabling high spatial resolution but demanding very precise
  observations. Realistically measurable quantities are identified
  through simulated observations of synthetic spectral lines. <BR />
  Results: In normal stars, line profile ratios between various transit
  phases may vary by 0.5%, requiring S/N ≳ 5000 for meaningful spectral
  reconstruction. While not yet realistic for individual spectral lines,
  this is achievable for cool stars by averaging over numerous lines
  with similar parameters. <BR /> Conclusions: For bright host stars of
  large transiting planets, spatially resolved spectroscopy is currently
  practical. More observable targets are likely to be found in the near
  future by ongoing photometric searches.

Title: Contributions of the Cherenkov Telescope Array (CTA) to
    the 6th International Symposium on High-Energy Gamma-Ray Astronomy
    (Gamma 2016)
Authors: CTA Consortium, The; :; Abchiche, A.; Abeysekara, U.; Abril,
   Ó.; Acero, F.; Acharya, B. S.; Adams, C.; Agnetta, G.; Aharonian,
   F.; Akhperjanian, A.; Albert, A.; Alcubierre, M.; Alfaro, J.; Alfaro,
   R.; Allafort, A. J.; Aloisio, R.; Amans, J. -P.; Amato, E.; Ambrogi,
   L.; Ambrosi, G.; Ambrosio, M.; Anderson, J.; Anduze, M.; Angüner,
   E. O.; Antolini, E.; Antonelli, L. A.; Antonucci, M.; Antonuccio,
   V.; Antoranz, P.; Aramo, C.; Aravantinos, A.; Araya, M.; Arcaro, C.;
   Arezki, B.; Argan, A.; Armstrong, T.; Arqueros, F.; Arrabito, L.;
   Arrieta, M.; Asano, K.; Ashley, M.; Aubert, P.; Singh, C. B.; Babic,
   A.; Backes, M.; Bais, A.; Bajtlik, S.; Balazs, C.; Balbo, M.; Balis,
   D.; Balkowski, C.; Ballester, O.; Ballet, J.; Balzer, A.; Bamba,
   A.; Bandiera, R.; Barber, A.; Barbier, C.; Barcelo, M.; Barkov,
   M.; Barnacka, A.; Barres de Almeida, U.; Barrio, J. A.; Basso, S.;
   Bastieri, D.; Bauer, C.; Becciani, U.; Becherini, Y.; Becker Tjus,
   J.; Beckmann, V.; Bednarek, W.; Benbow, W.; Benedico Ventura, D.;
   Berdugo, J.; Berge, D.; Bernardini, E.; Bernardini, M. G.; Bernhard,
   S.; Bernlöhr, K.; Bertucci, B.; Besel, M. -A.; Beshley, V.; Bhatt,
   N.; Bhattacharjee, P.; Bhattacharyya, W.; Bhattachryya, S.; Biasuzzi,
   B.; Bicknell, G.; Bigongiari, C.; Biland, A.; Bilinsky, A.; Bilnik,
   W.; Biondo, B.; Bird, R.; Bird, T.; Bissaldi, E.; Bitossi, M.;
   Blanch, O.; Blasi, P.; Blazek, J.; Bockermann, C.; Boehm, C.; Bogacz,
   L.; Bogdan, M.; Bohacova, M.; Boisson, C.; Boix, J.; Bolmont, J.;
   Bonanno, G.; Bonardi, A.; Bonavolontà, C.; Bonifacio, P.; Bonnarel,
   F.; Bonnoli, G.; Borkowski, J.; Bose, R.; Bosnjak, Z.; Böttcher, M.;
   Bousquet, J. -J.; Boutonnet, C.; Bouyjou, F.; Bowman, L.; Braiding,
   C.; Brantseg, T.; Brau-Nogué, S.; Bregeon, J.; Briggs, M.; Brigida,
   M.; Bringmann, T.; Brisken, W.; Bristow, D.; Britto, R.; Brocato, E.;
   Bron, S.; Brook, P.; Brooks, W.; Brown, A. M.; Brügge, K.; Brun, F.;
   Brun, P.; Brun, P.; Brunetti, G.; Brunetti, L.; Bruno, P.; Buanes,
   T.; Bucciantini, N.; Buchholtz, G.; Buckley, J.; Bugaev, V.; Bühler,
   R.; Bulgarelli, A.; Bulik, T.; Burton, M.; Burtovoi, A.; Busetto,
   G.; Buson, S.; Buss, J.; Byrum, K.; Cadoux, F.; Calvo Tovar, J.;
   Cameron, R.; Canelli, F.; Canestrari, R.; Capalbi, M.; Capasso, M.;
   Capobianco, G.; Caproni, A.; Caraveo, P.; Cardenzana, J.; Cardillo,
   M.; Carius, S.; Carlile, C.; Carosi, A.; Carosi, R.; Carquín, E.;
   Carr, J.; Carroll, M.; Carter, J.; Carton, P. -H.; Casandjian, J. -M.;
   Casanova, S.; Casanova, S.; Cascone, E.; Casiraghi, M.; Castellina,
   A.; Castroviejo Mora, J.; Catalani, F.; Catalano, O.; Catalanotti,
   S.; Cauz, D.; Cavazzani, S.; Cerchiara, P.; Chabanne, E.; Chadwick,
   P.; Chaleil, T.; Champion, C.; Chatterjee, A.; Chaty, S.; Chaves, R.;
   Chen, A.; Chen, X.; Chen, X.; Cheng, K.; Chernyakova, M.; Chiappetti,
   L.; Chikawa, M.; Chinn, D.; Chitnis, V. R.; Cho, N.; Christov, A.;
   Chudoba, J.; Cieślar, M.; Ciocci, M. A.; Clay, R.; Colafrancesco,
   S.; Colin, P.; Colley, J. -M.; Colombo, E.; Colome, J.; Colonges, S.;
   Conforti, V.; Connaughton, V.; Connell, S.; Conrad, J.; Contreras,
   J. L.; Coppi, P.; Corbel, S.; Coridian, J.; Cornat, R.; Corona,
   P.; Corti, D.; Cortina, J.; Cossio, L.; Costa, A.; Costantini, H.;
   Cotter, G.; Courty, B.; Covino, S.; Covone, G.; Crimi, G.; Criswell,
   S. J.; Crocker, R.; Croston, J.; Cuadra, J.; Cumani, P.; Cusumano,
   G.; Da Vela, P.; Dale, Ø.; D'Ammando, F.; Dang, D.; Dang, V. T.;
   Dangeon, L.; Daniel, M.; Davids, I.; Davids, I.; Dawson, B.; Dazzi,
   F.; de Aguiar Costa, B.; De Angelis, A.; de Araujo Cardoso, R. F.;
   De Caprio, V.; de Cássia dos Anjos, R.; De Cesare, G.; De Franco,
   A.; De Frondat, F.; de Gouveia Dal Pino, E. M.; de la Calle, I.;
   De Lisio, C.; de los Reyes Lopez, R.; De Lotto, B.; De Luca, A.; de
   Mello Neto, J. R. T.; de Naurois, M.; de Oña Wilhelmi, E.; De Palma,
   F.; De Persio, F.; de Souza, V.; Decock, G.; Decock, J.; Deil, C.;
   Del Santo, M.; Delagnes, E.; Deleglise, G.; Delgado, C.; Delgado, J.;
   della Volpe, D.; Deloye, P.; Detournay, M.; Dettlaff, A.; Devin, J.;
   Di Girolamo, T.; Di Giulio, C.; Di Paola, A.; Di Pierro, F.; Diaz,
   M. A.; Díaz, C.; Dib, C.; Dick, J.; Dickinson, H.; Diebold, S.;
   Digel, S.; Dipold, J.; Disset, G.; Distefano, A.; Djannati-Ataï, A.;
   Doert, M.; Dohmke, M.; Domínguez, A.; Dominik, N.; Dominique, J. -L.;
   Dominis Prester, D.; Donat, A.; Donnarumma, I.; Dorner, D.; Doro,
   M.; Dournaux, J. -L.; Downes, T.; Doyle, K.; Drake, G.; Drappeau,
   S.; Drass, H.; Dravins, D.; Drury, L.; Dubus, G.; Ducci, L.; Dumas,
   D.; Dundas Morå, K.; Durand, D.; D'Urso, D.; Dwarkadas, V.; Dyks,
   J.; Dyrda, M.; Ebr, J.; Edy, E.; Egberts, K.; Eger, P.; Egorov, A.;
   Einecke, S.; Eisch, J.; Eisenkolb, F.; Eleftheriadis, C.; Elsaesser,
   D.; Elsässer, D.; Emmanoulopoulos, D.; Engelbrecht, C.; Engelhaupt,
   D.; Ernenwein, J. -P.; Escarate, P.; Eschbach, S.; Espinoza, C.;
   Evans, P.; Fairbairn, M.; Falceta-Goncalves, D.; Falcone, A.; Fallah
   Ramazani, V.; Fantinel, D.; Farakos, K.; Farnier, C.; Farrell, E.;
   Fasola, G.; Favre, Y.; Fede, E.; Fedora, R.; Fedorova, E.; Fegan, S.;
   Ferenc, D.; Fernandez-Alonso, M.; Fernández-Barral, A.; Ferrand, G.;
   Ferreira, O.; Fesquet, M.; Fetfatzis, P.; Fiandrini, E.; Fiasson, A.;
   Filipčič, A.; Filipovic, M.; Fink, D.; Finley, C.; Finley, J. P.;
   Finoguenov, A.; Fioretti, V.; Fiorini, M.; Fleischhack, H.; Flores,
   H.; Florin, D.; Föhr, C.; Fokitis, E.; Fonseca, M. V.; Font, L.;
   Fontaine, G.; Fontes, B.; Fornasa, M.; Fornasa, M.; Förster, A.;
   Fortin, P.; Fortson, L.; Fouque, N.; Franckowiak, A.; Franckowiak,
   A.; Franco, F. J.; Freire Mota Albuquerque, I.; Freixas Coromina,
   L.; Fresnillo, L.; Fruck, C.; Fuessling, M.; Fugazza, D.; Fujita, Y.;
   Fukami, S.; Fukazawa, Y.; Fukuda, T.; Fukui, Y.; Funk, S.; Furniss, A.;
   Gäbele, W.; Gabici, S.; Gadola, A.; Galindo, D.; Gall, D. D.; Gallant,
   Y.; Galloway, D.; Gallozzi, S.; Galvez, J. A.; Gao, S.; Garcia, A.;
   Garcia, B.; García Gil, R.; Garcia López, R.; Garczarczyk, M.;
   Gardiol, D.; Gargano, C.; Gargano, F.; Garozzo, S.; Garrecht, F.;
   Garrido, L.; Garrido-Ruiz, M.; Gascon, D.; Gaskins, J.; Gaudemard,
   J.; Gaug, M.; Gaweda, J.; Gebhardt, B.; Gebyehu, M.; Geffroy, N.;
   Genolini, B.; Gerard, L.; Ghalumyan, A.; Ghedina, A.; Ghislain, P.;
   Giammaria, P.; Giannakaki, E.; Gianotti, F.; Giarrusso, S.; Giavitto,
   G.; Giebels, B.; Gieras, T.; Giglietto, N.; Gika, V.; Gimenes, R.;
   Giomi, M.; Giommi, P.; Giordano, F.; Giovannini, G.; Girardot, P.;
   Giro, E.; Giroletti, M.; Gironnet, J.; Giuliani, A.; Glicenstein,
   J. -F.; Gnatyk, R.; Godinovic, N.; Goldoni, P.; Gomez, G.; Gonzalez,
   M. M.; González, A.; Gora, D.; Gothe, K. S.; Gotz, D.; Goullon, J.;
   Grabarczyk, T.; Graciani, R.; Graham, J.; Grandi, P.; Granot, J.;
   Grasseau, G.; Gredig, R.; Green, A. J.; Green, A. M.; Greenshaw, T.;
   Grenier, I.; Griffiths, S.; Grillo, A.; Grondin, M. -H.; Grube, J.;
   Grudzinska, M.; Grygorczuk, J.; Guarino, V.; Guberman, D.; Gunji, S.;
   Gyuk, G.; Hadasch, D.; Hagedorn, A.; Hagge, L.; Hahn, J.; Hakobyan,
   H.; Hara, S.; Hardcastle, M. J.; Hassan, T.; Hatanaka, K.; Haubold,
   T.; Haupt, A.; Hayakawa, T.; Hayashida, M.; Heller, M.; Heller,
   R.; Helo, J. C.; Henault, F.; Henri, G.; Hermann, G.; Hermel, R.;
   Herrera Llorente, J.; Herrera Llorente, J.; Herrero, A.; Hervet,
   O.; Hidaka, N.; Hinton, J.; Hirai, W.; Hirotani, K.; Hnatyk, B.;
   Hoang, J.; Hoffmann, D.; Hofmann, W.; Holch, T.; Holder, J.; Hooper,
   S.; Horan, D.; Hörandel, J.; Hörbe, M.; Horns, D.; Horvath, P.;
   Hose, J.; Houles, J.; Hovatta, T.; Hrabovsky, M.; Hrupec, D.; Huet,
   J. -M.; Huetten, M.; Hughes, G.; Hui, D.; Humensky, T. B.; Hussein,
   M.; Iacovacci, M.; Ibarra, A.; Ikeno, Y.; Illa, J. M.; Impiombato,
   D.; Inada, T.; Incorvaia, S.; Infante, L.; Inome, Y.; Inoue, S.;
   Inoue, T.; Inoue, Y.; Iocco, F.; Ioka, K.; Iori, M.; Ishio, K.;
   Ishio, K.; Israel, G. L.; Iwamura, Y.; Jablonski, C.; Jacholkowska,
   A.; Jacquemier, J.; Jamrozy, M.; Janecek, P.; Janiak, M.; Jankowsky,
   D.; Jankowsky, F.; Jean, P.; Jegouzo, I.; Jenke, P.; Jimenez, J. J.;
   Jingo, M.; Jingo, M.; Jocou, L.; Jogler, T.; Johnson, C. A.; Jones,
   M.; Josselin, M.; Journet, L.; Jung, I.; Kaaret, P.; Kagaya, M.;
   Kakuwa, J.; Kalekin, O.; Kalkuhl, C.; Kamon, H.; Kankanyan, R.;
   Karastergiou, A.; Kärcher, K.; Karczewski, M.; Karkar, S.; Karn, P.;
   Kasperek, J.; Katagiri, H.; Kataoka, J.; Katarzyński, K.; Kato, S.;
   Katz, U.; Kawanaka, N.; Kaye, L.; Kazanas, D.; Kelley-Hoskins, N.;
   Kersten, J.; Khélifi, B.; Kieda, D. B.; Kihm, T.; Kimeswenger, S.;
   Kisaka, S.; Kishida, S.; Kissmann, R.; Klepser, S.; Kluźniak, W.;
   Knapen, J.; Knapp, J.; Knödlseder, J.; Koch, B.; Köck, F.; Kocot,
   J.; Kohri, K.; Kokkotas, K.; Kokkotas, K.; Kolitzus, D.; Komin, N.;
   Kominis, I.; Kong, A.; Konno, Y.; Kosack, K.; Koss, G.; Kossatz, M.;
   Kowal, G.; Koyama, S.; Kozioł, J.; Kraus, M.; Krause, J.; Krause, M.;
   Krawzcynski, H.; Krennrich, F.; Kretzschmann, A.; Kruger, P.; Kubo, H.;
   Kudryavtsev, V.; Kukec Mezek, G.; Kuklis, M.; Kuroda, H.; Kushida, J.;
   La Barbera, A.; La Palombara, N.; La Parola, V.; La Rosa, G.; Laffon,
   H.; Lahmann, R.; Lakicevic, M.; Lalik, K.; Lamanna, G.; Landriu,
   D.; Landt, H.; Lang, R. G.; Lapington, J.; Laporte, P.; Le Fèvre,
   J. -P.; Le Flour, T.; Le Sidaner, P.; Lee, S. -H.; Lee, W. H.; Lees,
   J. -P.; Lefaucheur, J.; Leffhalm, K.; Leich, H.; Leigui de Oliveira,
   M. A.; Lelas, D.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J. -P.;
   Leonard, R.; Leoni, R.; Lessio, L.; Leto, G.; Leveque, A.; Lieunard,
   B.; Limon, M.; Lindemann, R.; Lindfors, E.; Linhoff, L.; Liolios,
   A.; Lipniacka, A.; Lockart, H.; Lohse, T.; Łokas, E.; Lombardi, S.;
   Longo, F.; Lopatin, A.; Lopez, M.; Loreggia, D.; Louge, T.; Louis,
   F.; Louys, M.; Lucarelli, F.; Lucchesi, D.; Lüdecke, H.; Luigi, T.;
   Luque-Escamilla, P. L.; Lyard, E.; Maccarone, M. C.; Maccarone, T.;
   Maccarone, T. J.; Mach, E.; Madejski, G. M.; Madonna, A.; Magniette,
   F.; Magniez, A.; Mahabir, M.; Maier, G.; Majumdar, P.; Majumdar, P.;
   Makariev, M.; Malaguti, G.; Malaspina, G.; Mallot, A. K.; Malouf,
   A.; Maltezos, S.; Malyshev, D.; Mancilla, A.; Mandat, D.; Maneva, G.;
   Manganaro, M.; Mangano, S.; Manigot, P.; Mankushiyil, N.; Mannheim, K.;
   Maragos, N.; Marano, D.; Marchegiani, P.; Marcomini, J. A.; Marcowith,
   A.; Mariotti, M.; Marisaldi, M.; Markoff, S.; Martens, C.; Martí,
   J.; Martin, J. -M.; Martin, L.; Martin, P.; Martínez, G.; Martínez,
   M.; Martínez, O.; Martynyuk-Lototskyy, K.; Marx, R.; Masetti, N.;
   Massimino, P.; Mastichiadis, A.; Mastroianni, S.; Mastropietro, M.;
   Masuda, S.; Matsumoto, H.; Matsuoka, S.; Matthews, N.; Mattiazzo, S.;
   Maurin, G.; Maxted, N.; Maxted, N.; Maya, J.; Mayer, M.; Mazin, D.;
   Mazziotta, M. N.; Mc Comb, L.; McCubbin, N.; McHardy, I.; Medina,
   C.; Mehrez, F.; Melioli, C.; Melkumyan, D.; Melse, T.; Mereghetti,
   S.; Merk, M.; Mertsch, P.; Meunier, J. -L.; Meures, T.; Meyer, M.;
   Meyrelles, J. L., jr; Miccichè, A.; Michael, T.; Michałowski, J.;
   Mientjes, P.; Mievre, I.; Mihailidis, A.; Miller, J.; Mineo, T.;
   Minuti, M.; Mirabal, N.; Mirabel, F.; Miranda, J. M.; Mirzoyan, R.;
   Mitchell, A.; Mizuno, T.; Moderski, R.; Mognet, I.; Mohammed, M.;
   Moharana, R.; Mohrmann, L.; Molinari, E.; Molyneux, P.; Monmarthe,
   E.; Monnier, G.; Montaruli, T.; Monte, C.; Monteiro, I.; Mooney, D.;
   Moore, P.; Moralejo, A.; Morello, C.; Moretti, E.; Mori, K.; Morris,
   P.; Morselli, A.; Moscato, F.; Motohashi, D.; Mottez, F.; Moudden,
   Y.; Moulin, E.; Mueller, S.; Mukherjee, R.; Munar, P.; Munari, M.;
   Mundell, C.; Mundet, J.; Muraishi, H.; Murase, K.; Muronga, A.; Murphy,
   A.; Nagar, N.; Nagataki, S.; Nagayoshi, T.; Nagesh, B. K.; Naito,
   T.; Nakajima, D.; Nakajima, D.; Nakamori, T.; Nakayama, K.; Nanni,
   J.; Naumann, D.; Nayman, P.; Nellen, L.; Nemmen, R.; Neronov, A.;
   Neyroud, N.; Nguyen, T.; Nguyen, T. T.; Nguyen Trung, T.; Nicastro, L.;
   Nicolau-Kukliński, J.; Niederwanger, F.; Niedźwiecki, A.; Niemiec,
   J.; Nieto, D.; Nievas-Rosillo, M.; Nikolaidis, A.; Nikołajuk, M.;
   Nishijima, K.; Nishikawa, K. -I.; Nishiyama, G.; Noda, K.; Noda,
   K.; Nogues, L.; Nolan, S.; Northrop, R.; Nosek, D.; Nöthe, M.;
   Novosyadlyj, B.; Nozka, L.; Nunio, F.; Oakes, L.; O'Brien, P.; Ocampo,
   C.; Occhipinti, G.; Ochoa, J. P.; OFaolain de Bhroithe, A.; Oger, R.;
   Ohira, Y.; Ohishi, M.; Ohm, S.; Ohoka, H.; Okazaki, N.; Okumura, A.;
   Olive, J. -F.; Olszowski, D.; Ong, R. A.; Ono, S.; Orienti, M.; Orito,
   R.; Orlati, A.; Osborne, J.; Ostrowski, M.; Ottaway, D.; Otte, N.;
   Öttl, S.; Ovcharov, E.; Oya, I.; Ozieblo, A.; Padovani, M.; Pagano,
   I.; Paiano, S.; Paizis, A.; Palacio, J.; Palatka, M.; Pallotta, J.;
   Panagiotidis, K.; Panazol, J. -L.; Paneque, D.; Panter, M.; Panzera,
   M. R.; Paoletti, R.; Paolillo, M.; Papayannis, A.; Papyan, G.; Paravac,
   A.; Paredes, J. M.; Pareschi, G.; Park, N.; Parsons, D.; Paśko, P.;
   Pavy, S.; Pech, M.; Peck, A.; Pedaletti, G.; Pe'er, A.; Peet, S.;
   Pelat, D.; Pepato, A.; Perez, M. d. C.; Perri, L.; Perri, M.; Persic,
   M.; Persic, M.; Petrashyk, A.; Petrucci, P. -O.; Petruk, O.; Peyaud,
   B.; Pfeifer, M.; Pfeiffer, G.; Piano, G.; Pieloth, D.; Pierre, E.;
   Pinto de Pinho, F.; García, C. Pio; Piret, Y.; Pisarski, A.; Pita,
   S.; Platos, Ł.; Platzer, R.; Podkladkin, S.; Pogosyan, L.; Pohl,
   M.; Poinsignon, P.; Pollo, A.; Porcelli, A.; Porthault, J.; Potter,
   W.; Poulios, S.; Poutanen, J.; Prandini, E.; Prandini, E.; Prast, J.;
   Pressard, K.; Principe, G.; Profeti, F.; Prokhorov, D.; Prokoph, H.;
   Prouza, M.; Pruchniewicz, R.; Pruteanu, G.; Pueschel, E.; Pühlhofer,
   G.; Puljak, I.; Punch, M.; Pürckhauer, S.; Pyzioł, R.; Queiroz,
   F.; Quel, E. J.; Quinn, J.; Quirrenbach, A.; Rafighi, I.; Rainò, S.;
   Rajda, P. J.; Rameez, M.; Rando, R.; Rannot, R. C.; Rataj, M.; Ravel,
   T.; Razzaque, S.; Reardon, P.; Reichardt, I.; Reimann, O.; Reimer,
   A.; Reimer, O.; Reisenegger, A.; Renaud, M.; Renner, S.; Reposeur,
   T.; Reville, B.; Rezaeian, A.; Rhode, W.; Ribeiro, D.; Ribeiro Prado,
   R.; Ribó, M.; Richards, G.; Richer, M. G.; Richtler, T.; Rico, J.;
   Ridky, J.; Rieger, F.; Riquelme, M.; Ristori, P. R.; Rivoire, S.; Rizi,
   V.; Roache, E.; Rodriguez, J.; Rodriguez Fernandez, G.; Rodríguez
   Vázquez, J. J.; Rojas, G.; Romano, P.; Romeo, G.; Roncadelli, M.;
   Rosado, J.; Rose, J.; Rosen, S.; Rosier Lees, S.; Ross, D.; Rouaix,
   G.; Rousselle, J.; Rovero, A. C.; Rowell, G.; Roy, F.; Royer, S.;
   Rubini, A.; Rudak, B.; Rugliancich, A.; Rujopakarn, W.; Rulten,
   C.; Rupiński, M.; Russo, F.; Russo, F.; Rutkowski, K.; Saavedra,
   O.; Sabatini, S.; Sacco, B.; Sadeh, I.; Saemann, E. O.; Safi-Harb,
   S.; Saggion, A.; Sahakian, V.; Saito, T.; Sakaki, N.; Sakurai, S.;
   Salamon, A.; Salega, M.; Salek, D.; Salesa Greus, F.; Salgado, J.;
   Salina, G.; Salinas, L.; Salini, A.; Sanchez, D.; Sanchez-Conde, M.;
   Sandaker, H.; Sandoval, A.; Sangiorgi, P.; Sanguillon, M.; Sano, H.;
   Santander, M.; Santangelo, A.; Santos, E. M.; Santos-Lima, R.; Sanuy,
   A.; Sapozhnikov, L.; Sarkar, S.; Satalecka, K.; Satalecka, K.; Sato,
   Y.; Savalle, R.; Sawada, M.; Sayède, F.; Schanne, S.; Schanz, T.;
   Schioppa, E. J.; Schlenstedt, S.; Schmid, J.; Schmidt, T.; Schmoll,
   J.; Schneider, M.; Schoorlemmer, H.; Schovanek, P.; Schubert, A.;
   Schullian, E. -M.; Schultze, J.; Schulz, A.; Schulz, S.; Schure, K.;
   Schussler, F.; Schwab, T.; Schwanke, U.; Schwarz, J.; Schweizer, T.;
   Schwemmer, S.; Schwendicke, U.; Schwerdt, C.; Sciacca, E.; Scuderi,
   S.; Segreto, A.; Seiradakis, J. -H.; Sembroski, G. H.; Semikoz, D.;
   Sergijenko, O.; Serre, N.; Servillat, M.; Seweryn, K.; Shafi, N.;
   Shalchi, A.; Sharma, M.; Shayduk, M.; Shellard, R. C.; Shibata, T.;
   Shigenaka, A.; Shilon, I.; Shum, E.; Sidoli, L.; Sidz, M.; Sieiro, J.;
   Siejkowski, H.; Silk, J.; Sillanpää, A.; Simone, D.; Simpson, H.;
   Singh, B. B.; Sinha, A.; Sironi, G.; Sitarek, J.; Sizun, P.; Sliusar,
   V.; Sliusar, V.; Smith, A.; Sobczyńska, D.; Sol, H.; Sottile, G.;
   Sowiński, M.; Spanier, F.; Spengler, G.; Spiga, R.; Stadler, R.;
   Stahl, O.; Stamerra, A.; Stanič, S.; Starling, R.; Staszak, D.;
   Stawarz, Ł.; Steenkamp, R.; Stefanik, S.; Stegmann, C.; Steiner, S.;
   Stella, C.; Stephan, M.; Stergioulas, N.; Sternberger, R.; Sterzel, M.;
   Stevenson, B.; Stinzing, F.; Stodulska, M.; Stodulski, M.; Stolarczyk,
   T.; Stratta, G.; Straumann, U.; Stringhetti, L.; Strzys, M.; Stuik,
   R.; Sulanke, K. -H.; Suomijärvi, T.; Supanitsky, A. D.; Suric, T.;
   Sushch, I.; Sutcliffe, P.; Sykes, J.; Szanecki, M.; Szepieniec, T.;
   Szwarnog, P.; Tacchini, A.; Tachihara, K.; Tagliaferri, G.; Tajima,
   H.; Takahashi, H.; Takahashi, K.; Takahashi, M.; Takalo, L.; Takami,
   S.; Takata, J.; Takeda, J.; Talbot, G.; Tam, T.; Tanaka, M.; Tanaka,
   S.; Tanaka, T.; Tanaka, Y.; Tanci, C.; Tanigawa, S.; Tavani, M.;
   Tavecchio, F.; Tavernet, J. -P.; Tayabaly, K.; Taylor, A.; Tejedor,
   L. A.; Telezhinsky, I.; Temme, F.; Temnikov, P.; Tenzer, C.; Terada,
   Y.; Terrazas, J. C.; Terrier, R.; Terront, D.; Terzic, T.; Tescaro,
   D.; Teshima, M.; Teshima, M.; Testa, V.; Tezier, D.; Thayer, J.;
   Thornhill, J.; Thoudam, S.; Thuermann, D.; Tibaldo, L.; Tiengo,
   A.; Timpanaro, M. C.; Tiziani, D.; Tluczykont, M.; Todero Peixoto,
   C. J.; Tokanai, F.; Tokarz, M.; Toma, K.; Tomastik, J.; Tomono, Y.;
   Tonachini, A.; Tonev, D.; Torii, K.; Tornikoski, M.; Torres, D. F.;
   Torres, M.; Torresi, E.; Toso, G.; Tosti, G.; Totani, T.; Tothill, N.;
   Toussenel, F.; Tovmassian, G.; Toyama, T.; Travnicek, P.; Trichard,
   C.; Trifoglio, M.; Troyano Pujadas, I.; Trzeciak, M.; Tsinganos, K.;
   Tsujimoto, S.; Tsuru, T.; Uchiyama, Y.; Umana, G.; Umetsu, Y.; Upadhya,
   S. S.; Uslenghi, M.; Vagelli, V.; Vagnetti, F.; Valdes-Galicia, J.;
   Valentino, M.; Vallania, P.; Valore, L.; van Driel, W.; van Eldik,
   C.; van Soelen, B.; Vandenbroucke, J.; Vanderwalt, J.; Vasileiadis,
   G.; Vassiliev, V.; Vázquez, J. R.; Vázquez Acosta, M. L.; Vecchi,
   M.; Vega, A.; Vegas, I.; Veitch, P.; Venault, P.; Venema, L.; Venter,
   C.; Vercellone, S.; Vergani, S.; Verma, K.; Verzi, V.; Vettolani,
   G. P.; Veyssiere, C.; Viana, A.; Viaux, N.; Vicha, J.; Vigorito,
   C.; Vincent, P.; Vincent, S.; Vink, J.; Vittorini, V.; Vlahakis, N.;
   Vlahos, L.; Voelk, H.; Voisin, V.; Vollhardt, A.; Volpicelli, A.; von
   Brand, H.; Vorobiov, S.; Vovk, I.; Vrastil, M.; Vu, L. V.; Vuillaume,
   T.; Wagner, R.; Wagner, R.; Wagner, S. J.; Wakely, S. P.; Walstra, T.;
   Walter, R.; Walther, T.; Ward, J. E.; Ward, M.; Warda, K.; Warren,
   D.; Wassberg, S.; Watson, J. J.; Wawer, P.; Wawrzaszek, R.; Webb,
   N.; Wegner, P.; Weiner, O.; Weinstein, A.; Wells, R.; Werner, F.;
   Wetteskind, H.; White, M.; White, R.; Więcek, M.; Wierzcholska, A.;
   Wiesand, S.; Wijers, R.; Wilcox, P.; Wild, N.; Wilhelm, A.; Wilkinson,
   M.; Will, M.; Will, M.; Williams, D. A.; Williams, J. T.; Willingale,
   R.; Wilson, N.; Winde, M.; Winiarski, K.; Winkler, H.; Winter, M.;
   Wischnewski, R.; Witt, E.; Wojcik, P.; Wolf, D.; Wood, M.; Wörnlein,
   A.; Wu, E.; Wu, T.; Yadav, K. K.; Yamamoto, H.; Yamamoto, T.; Yamane,
   N.; Yamazaki, R.; Yanagita, S.; Yang, L.; Yelos, D.; Yoshida, A.;
   Yoshida, M.; Yoshida, T.; Yoshiike, S.; Yoshikoshi, T.; Yu, P.;
   Zabalza, V.; Zaborov, D.; Zacharias, M.; Zaharijas, G.; Zajczyk,
   A.; Zampieri, L.; Zandanel, F.; Zanmar Sanchez, R.; Zaric, D.;
   Zavrtanik, D.; Zavrtanik, M.; Zdziarski, A.; Zech, A.; Zechlin, H.;
   Zhao, A.; Zhdanov, V.; Ziegler, A.; Ziemann, J.; Ziętara, K.; Zink,
   A.; Ziółkowski, J.; Zitelli, V.; Zoli, A.; Zorn, J.; Żychowski, P.
Bibcode: 2016arXiv161005151C
Altcode:
  List of contributions from the Cherenkov Telescope Array (CTA)
  Consortium presented at the 6th International Symposium on High-Energy
  Gamma-Ray Astronomy (Gamma 2016), July 11-15, 2016, in Heidelberg,
  Germany.

Title: Exoplanet Transits Enable High-Resolution Spectroscopy Across
    Spatially Resolved Stellar Surfaces
Authors: Dravins, Dainis; Ludwig, Hans-Günter; Dahlén, Erik;
   Pazira, Hiva
Bibcode: 2016csss.confE..66D
Altcode: 2016arXiv160703489D
  Observations of stellar surfaces ndash; except for the Sun ndash;
  are hampered by their tiny angular extent, while observed spectral
  lines are smeared by averaging over the stellar surface, and by stellar
  rotation. Exoplanet transits can be used to analyze stellar atmospheric
  structure, yielding high-resolution spectra across spatially highly
  resolved stellar surfaces, free from effects of spatial smearing and the
  rotational wavelength broadening present in full-disk spectra. During
  a transit, stellar surface portions successively become hidden, and
  differential spectroscopy between various transit phases provides
  spectra of those surface segments then hidden behind the planet. The
  small area subtended by even a large planet (about 1% of a main-sequence
  star) offers high spatial resolution but demands very precise
  observations. We demonstrate the reconstruction of photospheric Fe I
  line profilesnbsp;at a spectral resolution R=80,000 across the surface
  of the solar-type star HD 209458. Any detailed understanding of stellar
  atmospheres requires modeling with 3-dimensional hydrodynamics. The
  properties predicted by such models are mapped onto the precise
  spectral-line shapes, asymmetries and wavelength shifts, and their
  variation from the center to the limb across any stellar disk. This
  method provides a tool for testing and verifying such models. The
  method will soon become applicable to more diverse types of stars,
  thanks to new spectrometers on very large telescopes, and since ongoing
  photometric searches are expected to discover additional bright host
  stars of transiting exoplanets.&gt;

Title: Intensity interferometry: optical imaging with kilometer
    baselines
Authors: Dravins, Dainis
Bibcode: 2016SPIE.9907E..0MD
Altcode: 2016arXiv160703490D
  Optical imaging with microarcsecond resolution will reveal details
  across and outside stellar surfaces but requires kilometer-scale
  interferometers, challenging to realize either on the ground or in
  space. Intensity interferometry, electronically connecting independent
  telescopes, has a noise budget that relates to the electronic time
  resolution, circumventing issues of atmospheric turbulence. Extents up
  to a few km are becoming realistic with arrays of optical air Cherenkov
  telescopes (primarily erected for gamma-ray studies), enabling an
  optical equivalent of radio interferometer arrays. Pioneered by
  Hanbury Brown and Twiss, digital versions of the technique have now
  been demonstrated, reconstructing diffraction-limited images from
  laboratory measurements over hundreds of optical baselines. This review
  outlines the method from its beginnings, describes current experiments,
  and sketches prospects for future observations.

Title: Spatially Resolved Spectroscopy Across HD189733 (K1V) Using
    Exoplanet Transits
Authors: Gustavsson, Martin; Dravins, Dainis; Ludwig, Hans-Günter
Bibcode: 2016csss.confE..53G
Altcode:
  For testing 3-dimensional models of stellar atmospheres, spectroscopy
  across spatially resolved stellar surfaces would be desired with
  a spectral resolution of(R = 100,000) or more. Hydrodynamic models
  predict variations in line profile shapes, strengths, wavelength
  positions and asymmetries. These variations vary systematically between
  disk center and limb and as a function of line strength, excitation
  potential and wavelength region. However, except for a few supergiants
  and the Sun, current telescopes are not yet capable of resolving
  any stellar surfaces. One alternative method to resolve distant
  stellar surfaces, feasible already now, is differential spectroscopy
  of transiting exoplanet systems. By subtracting in-transit spectra
  from the spectrum outside of transit, the spectra from stellar surface
  portions temporarily hidden behind the planet can be disentangled. Since
  transiting planets cover only a small portion of the stellar surface,
  the method requires a very high signal-to-noise ratio, obtainable by
  averaging numerous similar spectral lines. We apply such differential
  spectroscopy on the 7.7 mag K1V star HD 189733 ('Alopex'*); its
  transiting planet covers ∼ 3% of its host star's surface, which
  is the deepest known transit among the brighter systems. Archival
  data from the ESO HARPS spectrometerare used to construct averaged
  profiles of photospheric Fe I lines, with the aim of comparing spatially
  resolved profiles to analogous synthetic line profiles computed from the
  3-dimensional hydrodynamic CO<SUP>5</SUP>BOLD model.<BR /> * We refer
  to HD 189733 as 'Alopex' (from the Greek 'αλɛπού'), denoting a
  fox related to the one that gave name to its constellation of Vulpecula.

Title: Stellar Intensity Interferometry over Kilometer Baselines:
    Optical aperture synthesis with electronically connected telescopes
Authors: Dravins, Dainis; Lagadec, Tiphaine; Nuñez, Paul D.
Bibcode: 2015IAUGA..2233727D
Altcode:
  Diffraction-limited optical imaging over kilometer baselines will reveal
  stellar surfaces, perhaps even resolving the silhouettes of transiting
  exoplanets. An opportunity is opening up with arrays of air Cherenkov
  telescopes used for intensity interferometry, a technique once pioneered
  by Hanbury Brown and Twiss. Being essentially insensitive to atmospheric
  turbulence, this permits both very long baselines and observing at
  short optical wavelengths.System verifications have been made in a
  large optics laboratory. Artificial stars were observed by a group of
  small telescopes equipped with nanosecond-resolving photon-counting
  detectors, their outputs processed in a digital correlator. Numerous
  telescope pairs at different baseline lengths and orientations build
  up a two-dimensional map of the second-order spatial coherence of the
  source, from which its image can be extracted.From up to 180 baselines
  thus measured, full two-dimensional images were reconstructed. As far as
  we are aware, these are the first diffraction-limited images produced
  by an array of optical telescopes connected only electronically
  in software, with no optical connections between them. Since the
  electronic signal from any telescope can be freely copied without
  loss of signal, very many baselines can be built up between dispersed
  telescopes. Using arrays of air Cherenkov telescopes, this should enable
  the optical equivalent of interferometric aperture synthesis arrays
  currently operating at radio wavelengths. arxiv.org/abs/1407.5993,
  Nature Commun., in press (2015)

Title: CTA Contributions to the 34th International Cosmic Ray
    Conference (ICRC2015)
Authors: CTA Consortium, The; :; Abchiche, A.; Abeysekara, U.; Abril,
   Ó.; Acero, F.; Acharya, B. S.; Actis, M.; Agnetta, G.; Aguilar,
   J. A.; Aharonian, F.; Akhperjanian, A.; Albert, A.; Alcubierre,
   M.; Alfaro, R.; Aliu, E.; Allafort, A. J.; Allan, D.; Allekotte,
   I.; Aloisio, R.; Amans, J. -P.; Amato, E.; Ambrogi, L.; Ambrosi, G.;
   Ambrosio, M.; Anderson, J.; Anduze, M.; Angüner, E. O.; Antolini, E.;
   Antonelli, L. A.; Antonucci, M.; Antonuccio, V.; Antoranz, P.; Aramo,
   C.; Aravantinos, A.; Argan, A.; Armstrong, T.; Arnaldi, H.; Arnold, L.;
   Arrabito, L.; Arrieta, M.; Arrieta, M.; Asano, K.; Asorey, H. G.; Aune,
   T.; Singh, C. B.; Babic, A.; Backes, M.; Bais, A.; Bajtlik, S.; Balazs,
   C.; Balbo, M.; Balis, D.; Balkowski, C.; Ballester, O.; Ballet, J.;
   Balzer, A.; Bamba, A.; Bandiera, R.; Barber, A.; Barbier, C.; Barceló,
   M.; Barnacka, A.; Barres de Almeida, U.; Barrio, J. A.; Basso, S.;
   Bastieri, D.; Bauer, C.; Baushev, A.; Becciani, U.; Becherini, Y.;
   Becker Tjus, J.; Beckmann, V.; Bednarek, W.; Benbow, W.; Benedico
   Ventura, D.; Berdugo, J.; Berge, D.; Bernardini, E.; Bernhard, S.;
   Bernlöhr, K.; Bertucci, B.; Besel, M. -A.; Bhatt, N.; Bhattacharjee,
   P.; Bhattachryya, S.; Biasuzzi, B.; Bicknell, G.; Bigongiari, C.;
   Biland, A.; Billotta, S.; Bilnik, W.; Biondo, B.; Bird, T.; Birsin,
   E.; Bissaldi, E.; Biteau, J.; Bitossi, M.; Blanch Bigas, O.; Blasi,
   P.; Boehm, C.; Bogacz, L.; Bogdan, M.; Bohacova, M.; Boisson, C.;
   Boix Gargallo, J.; Bolmont, J.; Bonanno, G.; Bonardi, A.; Bonifacio,
   P.; Bonnoli, G.; Borkowski, J.; Bose, R.; Bosnjak, Z.; Bottani, A.;
   Böttcher, M.; Bousquet, J. -J.; Boutonnet, C.; Bouyjou, F.; Braiding,
   C.; Brandt, L.; Brau-Nogué, S.; Bregeon, J.; Bretz, T.; Briggs,
   M.; Brigida, M.; Bringmann, T.; Brisken, W.; Brocato, E.; Brook, P.;
   Brown, A. M.; Brun, P.; Brunetti, G.; Brunetti, L.; Bruno, P.; Bryan,
   M.; Buanes, T.; Bucciantini, N.; Buchholtz, G.; Buckley, J.; Bugaev,
   V.; Bühler, R.; Bulgarelli, A.; Bulik, T.; Burton, M.; Burtovoi, A.;
   Busetto, G.; Buson, S.; Buss, J.; Byrum, K.; Cameron, R.; Camprecios,
   J.; Canelli, F.; Canestrari, R.; Cantu, S.; Capalbi, M.; Capasso, M.;
   Capobianco, G.; Caraveo, P.; Cardenzana, J.; Carius, S.; Carlile, C.;
   Carmona, E.; Carosi, A.; Carosi, R.; Carr, J.; Carroll, M.; Carter,
   J.; Carton, P. -H.; Caruso, R.; Casandjian, J. -M.; Casanova, S.;
   Cascone, E.; Casiraghi, M.; Castellina, A.; Catalano, O.; Catalanotti,
   S.; Cavazzani, S.; Cazaux, S.; Cefalà, M.; Cerchiara, P.; Cereda,
   M.; Cerruti, M.; Chabanne, E.; Chadwick, P.; Champion, C.; Chaty,
   S.; Chaves, R.; Cheimets, P.; Chen, A.; Chen, X.; Chernyakova, M.;
   Chiappetti, L.; Chikawa, M.; Chinn, D.; Chitnis, V. R.; Cho, N.;
   Christov, A.; Chudoba, J.; Cieślar, M.; Cillis, A.; Ciocci, M. A.;
   Clay, R.; Cohen-Tanugi, J.; Colafrancesco, S.; Colin, P.; Colombo,
   E.; Colome, J.; Colonges, S.; Compin, M.; Conforti, V.; Connaughton,
   V.; Connell, S.; Conrad, J.; Contreras, J. L.; Coppi, P.; Corbel, S.;
   Coridian, J.; Corona, P.; Corti, D.; Cortina, J.; Cossio, L.; Costa,
   A.; Costantini, H.; Cotter, G.; Courty, B.; Covino, S.; Covone, G.;
   Crimi, G.; Criswell, S. J.; Crocker, R.; Croston, J.; Cusumano, G.;
   Da Vela, P.; Dale, Ø.; D'Ammando, F.; Dang, D.; Daniel, M.; Davids,
   I.; Dawson, B.; Dazzi, F.; de Aguiar Costa, B.; De Angelis, A.; de
   Araujo Cardoso, R. F.; De Caprio, V.; De Cesare, G.; De Franco, A.;
   De Frondat, F.; de Gouveia Dal Pino, E. M.; de la Calle, I.; De La
   Vega, G. A.; de los Reyes Lopez, R.; De Lotto, B.; De Luca, A.; de
   Mello Neto, J. R. T.; de Naurois, M.; de Oña Wilhelmi, E.; De Palma,
   F.; de Souza, V.; Decock, G.; Deil, C.; Del Santo, M.; Delagnes, E.;
   Deleglise, G.; Delgado, C.; della Volpe, D.; Deloye, P.; Depaola, G.;
   Detournay, M.; Dettlaff, A.; Di Girolamo, T.; Di Giulio, C.; Di Paola,
   A.; Di Pierro, F.; Di Sciascio, G.; Díaz, C.; Dick, J.; Dickinson, H.;
   Diebold, S.; Diez, V.; Digel, S.; Dipold, J.; Disset, G.; Distefano,
   A.; Djannati-Ataï, A.; Doert, M.; Dohmke, M.; Domainko, W.; Dominik,
   N.; Dominis Prester, D.; Donat, A.; Donnarumma, I.; Dorner, D.; Doro,
   M.; Dournaux, J. -L.; Doyle, K.; Drake, G.; Dravins, D.; Drury, L.;
   Dubus, G.; Dumas, D.; Dumm, J.; Durand, D.; D'Urso, D.; Dwarkadas,
   V.; Dyks, J.; Dyrda, M.; Ebr, J.; Echaniz, J. C.; Edy, E.; Egberts,
   K.; Egberts, K.; Eger, P.; Einecke, S.; Eisch, J.; Eisenkolb, F.;
   Eleftheriadis, C.; Elsässer, D.; Emmanoulopoulos, D.; Engelbrecht,
   C.; Engelhaupt, D.; Ernenwein, J. -P.; Errando, M.; Eschbach, S.;
   Etchegoyen, A.; Evans, P.; Fairbairn, M.; Falcone, A.; Fantinel, D.;
   Farakos, K.; Farnier, C.; Farrell, E.; Farrell, S.; Fasola, G.; Fegan,
   S.; Feinstein, F.; Ferenc, D.; Fernandez, A.; Fernandez-Alonso, M.;
   Ferreira, O.; Fesquet, M.; Fetfatzis, P.; Fiasson, A.; Filipčič, A.;
   Filipovic, M.; Fink, D.; Finley, C.; Finley, J. P.; Finoguenov, A.;
   Fioretti, V.; Fiorini, M.; Firpo Curcoll, R.; Fleischhack, H.; Flores,
   H.; Florin, D.; Föhr, C.; Fokitis, E.; Font, L.; Fontaine, G.; Fontes,
   B.; Forest, F.; Fornasa, M.; Förster, A.; Fortin, P.; Fortson, L.;
   Fouque, N.; Franckowiak, A.; Franco, F. J.; Frankowski, A.; Frega,
   N.; Freire Mota Albuquerque, I.; Freixas Coromina, L.; Fresnillo,
   L.; Fruck, C.; Fuessling, M.; Fugazza, D.; Fujita, Y.; Fukami, S.;
   Fukazawa, Y.; Fukuda, T.; Fukui, Y.; Funk, S.; Gäbele, W.; Gabici,
   S.; Gadola, A.; Galante, N.; Gall, D. D.; Gallant, Y.; Galloway, D.;
   Gallozzi, S.; Gao, S.; Garcia, B.; García Gil, R.; Garcia López,
   R.; Garczarczyk, M.; Gardiol, D.; Gargano, C.; Gargano, F.; Garozzo,
   S.; Garrecht, F.; Garrido, D.; Garrido, L.; Gascon, D.; Gaskins,
   J.; Gaudemard, J.; Gaug, M.; Gaweda, J.; Geffroy, N.; Gérard, L.;
   Ghalumyan, A.; Ghedina, A.; Ghigo, M.; Ghislain, P.; Giannakaki, E.;
   Gianotti, F.; Giarrusso, S.; Giavitto, G.; Giebels, B.; Giglietto,
   N.; Gika, V.; Gimenes, R.; Giomi, M.; Giommi, P.; Giordano, F.;
   Giovannini, G.; Giro, E.; Giroletti, M.; Giuliani, A.; Glicenstein,
   J. -F.; Godinovic, N.; Goldoni, P.; Gomez Berisso, M.; Gomez Vargas,
   G. A.; Gonzalez, M. M.; González, A.; González, F.; González
   Muñoz, A.; Gothe, K. S.; Gotz, D.; Grabarczyk, T.; Graciani, R.;
   Grandi, P.; Grañena, F.; Granot, J.; Grasseau, G.; Gredig, R.;
   Green, A. J.; Green, A. M.; Greenshaw, T.; Grenier, I.; Grillo, A.;
   Grondin, M. -H.; Grube, J.; Grudzinska, M.; Grygorczuk, J.; Guarino,
   V.; Guberman, D.; Gunji, S.; Gyuk, G.; Hadasch, D.; Hagedorn, A.;
   Hahn, J.; Hakansson, N.; Hamer Heras, N.; Hanabata, Y.; Hara, S.;
   Hardcastle, M. J.; Harris, J.; Hassan, T.; Hatanaka, K.; Haubold,
   T.; Haupt, A.; Hayakawa, T.; Hayashida, M.; Heller, M.; Heller, R.;
   Henault, F.; Henri, G.; Hermann, G.; Hermel, R.; Herrera Llorente, J.;
   Herrero, A.; Hervet, O.; Hidaka, N.; Hinton, J.; Hirai, W.; Hirotani,
   K.; Hoard, D.; Hoffmann, D.; Hofmann, W.; Hofverberg, P.; Holch, T.;
   Holder, J.; Hooper, S.; Horan, D.; Hörandel, J. R.; Hormigos, S.;
   Horns, D.; Hose, J.; Houles, J.; Hovatta, T.; Hrabovsky, M.; Hrupec,
   D.; Huet, J. -M.; Hütten, M.; Humensky, T. B.; Huovelin, J.; Huppert,
   J. -F.; Iacovacci, M.; Ibarra, A.; Idźkowski, B.; Ikawa, D.; Illa,
   J. M.; Impiombato, D.; Incorvaia, S.; Inome, Y.; Inoue, S.; Inoue,
   T.; Inoue, Y.; Iocco, F.; Ioka, K.; Iori, M.; Ishio, K.; Israel,
   G. L.; Jablonski, C.; Jacholkowska, A.; Jacquemier, J.; Jamrozy,
   M.; Janecek, P.; Janiak, M.; Jankowsky, F.; Jean, P.; Jeanney, C.;
   Jegouzo, I.; Jenke, P.; Jimenez, J. J.; Jingo, M.; Jingo, M.; Jocou,
   L.; Jogler, T.; Johnson, C. A.; Journet, L.; Juffroy, C.; Jung,
   I.; Kaaret, P. E.; Kagaya, M.; Kakuwa, J.; Kalekin, O.; Kalkuhl, C.;
   Kankanyan, R.; Karastergiou, A.; Kärcher, K.; Karczewski, M.; Karkar,
   S.; Karn, P.; Kasperek, J.; Katagiri, H.; Kataoka, J.; Katarzyński,
   K.; Katz, U.; Kaufmann, S.; Kawanaka, N.; Kawashima, T.; Kazanas,
   D.; Kelley-Hoskins, N.; Kellner-Leidel, B.; Kendziorra, E.; Kersten,
   J.; Khélifi, B.; Kieda, D. B.; Kihm, T.; Kisaka, S.; Kissmann, R.;
   Klepser, S.; Kluźniak, W.; Knapen, J.; Knapp, J.; Knödlseder, J.;
   Köck, F.; Kocot, J.; Kodakkadan, A.; Kodani, K.; Kohri, K.; Kojima,
   T.; Kokkotas, K.; Kolitzus, D.; Komin, N.; Kominis, I.; Konno, Y.;
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   F.; Kretzschmann, A.; Kruger, P.; Kubo, H.; Kudryavtsev, V.; Kukec
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   D.; Le Fèvre, J. -P.; Le Flour, T.; Le Sidaner, P.; Lee, S. -H.; Lee,
   W. H.; Leffhalm, K.; Leich, H.; Leigui de Oliveira, M. A.; Lelas,
   D.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J. -P.; Leonard, R.;
   Leoni, R.; Lessio, L.; Leto, G.; Leveque, A.; Lieunard, B.; Limon,
   M.; Lindemann, R.; Lindfors, E.; Liolios, A.; Lipniacka, A.; Lockart,
   H.; Lohse, T.; Loiseau, D.; Łokas, E.; Lombardi, S.; Longo, F.;
   Longo, G.; Lopatin, A.; Lopez, M.; López-Coto, R.; López-Oramas,
   A.; Loreggia, D.; Louge, T.; Louis, F.; Lu, C. -C.; Lucarelli, F.;
   Lucchesi, D.; Lüdecke, H.; Luque-Escamilla, P. L.; Luz, O.; Lyard,
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   Madonna, A.; Mahabir, M.; Maier, G.; Majumdar, P.; Makariev, M.;
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   Ostrowski, M.; Otero, L. A.; Ottaway, D.; Otte, N.; Oya, I.; Ozieblo,
   A.; Padovani, M.; Pagano, I.; Paiano, S.; Paizis, A.; Palacio, J.;
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   D.; Panter, M.; Panzera, M. R.; Paoletti, R.; Paolillo, M.; Papayannis,
   A.; Papyan, G.; Paravac, A.; Paredes, J. M.; Pareschi, G.; Park, N.;
   Parsons, D.; Paśko, P.; Pavy, S.; Arribas, M. Paz; Pech, M.; Peck,
   A.; Pedaletti, G.; Peet, S.; Pelassa, V.; Pelat, D.; Peres, C.;
   Perez, M. d. C.; Perri, L.; Persic, M.; Petrashyk, A.; Petrucci,
   P. -O.; Peyaud, B.; Pfeifer, M.; Pfeiffer, G.; Piano, G.; Pichel,
   A.; Pieloth, D.; Pierbattista, M.; Pierre, E.; Pinto de Pinho, F.;
   García, C. Pio; Piret, Y.; Pita, S.; Planes, A.; Platino, M.; Platos,
   Ł.; Platzer, R.; Podkladkin, S.; Pogosyan, L.; Pohl, M.; Poinsignon,
   P.; Ponz, J. D.; Porcelli, A.; Potter, W.; Poulios, S.; Poutanen,
   J.; Prandini, E.; Prast, J.; Preece, R.; Profeti, F.; Prokhorov, D.;
   Prokoph, H.; Prouza, M.; Proyetti, M.; Pruchniewicz, R.; Pueschel,
   E.; Pühlhofer, G.; Puljak, I.; Punch, M.; Pyzioł, R.; Queiroz,
   F.; Quel, E. J.; Quinn, J.; Quirrenbach, A.; Racero, E.; Räck,
   T.; Rafalski, J.; Rafighi, I.; Rainò, S.; Rajda, P. J.; Rameez, M.;
   Rando, R.; Rannot, R. C.; Rataj, M.; Rateau, S.; Ravel, T.; Ravignani,
   D.; Razzaque, S.; Reardon, P.; Reimann, O.; Reimer, A.; Reimer, O.;
   Reitberger, K.; Renaud, M.; Renner, S.; Reposeur, T.; Rettig, R.;
   Reville, B.; Rhode, W.; Ribeiro, D.; Ribó, M.; Richards, G.; Richer,
   M. G.; Rico, J.; Ridky, J.; Rieger, F.; Ringegni, P.; Ristori, P. R.;
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   J.; Rodriguez Fernandez, G.; Rodríguez Vázquez, J. J.; Rogers, T.;
   Rojas, G.; Romano, P.; Romay Rodriguez, M. P.; Romeo, G.; Romero,
   G. E.; Roncadelli, M.; Rose, J.; Rosen, S.; Rosier Lees, S.; Ross,
   D.; Rossiter, P.; Rouaix, G.; Rousselle, J.; Rovero, A. C.; Rowell,
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   A.; Rulten, C.; Rupiński, M.; Russo, F.; Rutkowski, K.; Saavedra,
   O.; Sabatini, S.; Sacco, B.; Saemann, E. O.; Saggion, A.; Saha, L.;
   Sahakian, V.; Saito, K.; Saito, T.; Sakaki, N.; Salega, M.; Salek, D.;
   Salgado, J.; Salini, A.; Sanchez, D.; Sanchez, F.; Sanchez-Conde, M.;
   Sandaker, H.; Sandoval, A.; Sangiorgi, P.; Sanguillon, M.; Sano, H.;
   Santander, M.; Santangelo, A.; Santos, E. M.; Santos-Lima, R.; Sanuy,
   A.; Sapozhnikov, L.; Sarkar, S.; Satalecka, K.; Savalle, R.; Sawada,
   M.; Sayède, F.; Schafer, J.; Schanne, S.; Schanz, T.; Schioppa, E. J.;
   Schlenstedt, S.; Schlickeiser, R.; Schmidt, T.; Schmoll, J.; Schneider,
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   D.; Sol, H.; Sottile, G.; Sowiński, M.; Spanier, F.; Spengler, G.;
   Spiga, D.; Stadler, R.; Stahl, O.; Stamatescu, V.; Stamerra, A.;
   Stanič, S.; Starling, R.; Stawarz, Ł.; Steenkamp, R.; Stefanik, S.;
   Stegmann, C.; Steiner, S.; Stella, C.; Stergioulas, N.; Sternberger,
   R.; Sterzel, M.; Stevenson, B.; Stinzing, F.; Stodulska, M.; Stodulski,
   M.; Stolarczyk, T.; Straumann, U.; Strazzeri, E.; Stringhetti, L.;
   Strzys, M.; Stuik, R.; Sulanke, K. -H.; Supanitsky, A. D.; Suric, T.;
   Sushch, I.; Sutcliffe, P.; Sykes, J.; Szanecki, M.; Szepieniec, T.;
   Szwarnog, P.; Tacchini, A.; Tachihara, K.; Tagliaferri, G.; Tajima, H.;
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   Wagner, S. J.; Wakely, S. P.; Walter, R.; Walther, T.; Ward, J. E.;
   Ward, M.; Warda, K.; Warwick, R.; Wassberg, S.; Watson, J.; Wawer,
   P.; Wawrzaszek, R.; Webb, N.; Wegner, P.; Weinstein, A.; Weitzel, Q.;
   Wells, R.; Werner, F.; Werner, M.; Wetteskind, H.; White, M.; White,
   R.; Więcek, M.; Wierzcholska, A.; Wiesand, S.; Wijers, R.; Wild, N.;
   Wilhelm, A.; Wilkinson, M.; Will, M.; Williams, D. A.; Williams, J. T.;
   Willingale, R.; Winde, M.; Winiarski, K.; Winkler, H.; Wischnewski,
   R.; Wojcik, P.; Wolf, D.; Wood, M.; Wörnlein, A.; Wu, E.; Wu, T.;
   Yadav, K. K.; Yamamoto, H.; Yamamoto, T.; Yamazaki, R.; Yanagita, S.;
   Yang, L.; Yebras, J. M.; Yelos, D.; Yeung, W.; Yoshida, A.; Yoshida,
   T.; Yoshiike, S.; Yoshikoshi, T.; Yu, P.; Zabalza, V.; Zabalza, V.;
   Zacharias, M.; Zaharijas, G.; Zajczyk, A.; Zampieri, L.; Zandanel,
   F.; Zanin, R.; Zanmar Sanchez, R.; Zavrtanik, D.; Zavrtanik, M.;
   Zdziarski, A.; Zech, A.; Zechlin, H.; Zhao, A.; Ziegler, A.; Ziemann,
   J.; Ziętara, K.; Ziółkowski, J.; Zitelli, V.; Zoli, A.; Zurbach,
   C.; Żychowski, P.
Bibcode: 2015arXiv150805894C
Altcode:
  List of contributions from the CTA Consortium presented at the 34th
  International Cosmic Ray Conference, 30 July - 6 August 2015, The Hague,
  The Netherlands.

Title: Long-baseline optical intensity interferometry. Laboratory
    demonstration of diffraction-limited imaging
Authors: Dravins, Dainis; Lagadec, Tiphaine; Nuñez, Paul D.
Bibcode: 2015A&A...580A..99D
Altcode: 2015arXiv150605804D
  Context. A long-held vision has been to realize diffraction-limited
  optical aperture synthesis over kilometer baselines. This will
  enable imaging of stellar surfaces and their environments, and reveal
  interacting gas flows in binary systems. An opportunity is now opening
  up with the large telescope arrays primarily erected for measuring
  Cherenkov light in air induced by gamma rays. With suitable software,
  such telescopes could be electronically connected and also used for
  intensity interferometry. Second-order spatial coherence of light
  is obtained by cross correlating intensity fluctuations measured in
  different pairs of telescopes. With no optical links between them,
  the error budget is set by the electronic time resolution of a few
  nanoseconds. Corresponding light-travel distances are approximately
  one meter, making the method practically immune to atmospheric
  turbulence or optical imperfections, permitting both very long
  baselines and observing at short optical wavelengths. <BR /> Aims:
  Previous theoretical modeling has shown that full images should be
  possible to retrieve from observations with such telescope arrays. This
  project aims at verifying diffraction-limited imaging experimentally
  with groups of detached and independent optical telescopes. <BR />
  Methods: In a large optics laboratory, artificial stars (single
  and double, round and elliptic) were observed by an array of small
  telescopes. Using high-speed photon-counting solid-state detectors and
  real-time electronics, intensity fluctuations were cross-correlated over
  up to 180 baselines between pairs of telescopes, producing coherence
  maps across the interferometric Fourier-transform plane. <BR /> Results:
  These interferometric measurements were used to extract parameters about
  the simulated stars, and to reconstruct their two-dimensional images. As
  far as we are aware, these are the first diffraction-limited images
  obtained from an optical array only linked by electronic software, with
  no optical connections between the telescopes. <BR /> Conclusions: These
  experiments serve to verify the concepts for long-baseline aperture
  synthesis in the optical, somewhat analogous to radio interferometry.

Title: Stellar Spectroscopy during Exoplanet Transits: Revealing
    structures across stellar surfaces
Authors: Dravins, Dainis; Ludwig, Hans-Günter; Dahlén, Erik
Bibcode: 2015IAUGA..2233688D
Altcode:
  Exoplanet transits permit to study stellar surface portions that
  successively become hidden behind the planet. Differential spectroscopy
  between various transit phases reveals spectra of those stellar
  surface segments that were hidden. The deduced center-to-limb behavior
  of stellar spectral line shapes, asymmetries and wavelength shifts
  enables detailed tests of 3-dimensional hydrodynamic models of stellar
  atmospheres, such that are required for any precise determination
  of abundances or seismic properties. Such models can now be computed
  for widely different classes of stars (including metal-poor ones and
  white dwarfs), but have been feasible to test and verify only for the
  Sun with its resolved surface structure. Exoplanet transits may also
  occur across features such as starspots, whose magnetic signatures will
  be retrieved from spectra of sufficient fidelity.Knowing the precise
  background stellar spectra, also properties of exoplanet atmospheres
  are better constrained: e.g., the Rossiter-McLaughlin effect becomes
  resolved as not only a simple change of stellar wavelength, but as a
  variation of the full line profiles and their asymmetries.Such studies
  are challenging since exoplanets cover only a tiny fraction of the
  stellar disk. Current work, analyzing sequences of high-fidelity ESO
  UVES spectra, demonstrate that such spatially resolved stellar spectra
  can already be (marginally) retrieved in a few cases with the brightest
  host stars. Already in a near future, ongoing exoplanet surveys are
  likely to find further bright hosts that will enable such studies for
  various stellar types. http://arxiv.org/abs/1408.1402

Title: Optical aperture synthesis with electronically connected
    telescopes
Authors: Dravins, Dainis; Lagadec, Tiphaine; Nuñez, Paul D.
Bibcode: 2015NatCo...6.6852D
Altcode: 2015NatCo...6E6852D; 2015arXiv150404619D
  Highest resolution imaging in astronomy is achieved by interferometry,
  connecting telescopes over increasingly longer distances and
  at successively shorter wavelengths. Here, we present the first
  diffraction-limited images in visual light, produced by an array of
  independent optical telescopes, connected electronically only, with
  no optical links between them. With an array of small telescopes,
  second-order optical coherence of the sources is measured through
  intensity interferometry over 180 baselines between pairs of telescopes,
  and two-dimensional images reconstructed. The technique aims at
  diffraction-limited optical aperture synthesis over kilometre-long
  baselines to reach resolutions showing details on stellar surfaces
  and perhaps even the silhouettes of transiting exoplanets. Intensity
  interferometry circumvents problems of atmospheric turbulence that
  constrain ordinary interferometry. Since the electronic signal can be
  copied, many baselines can be built up between dispersed telescopes,
  and over long distances. Using arrays of air Cherenkov telescopes,
  this should enable the optical equivalent of interferometric arrays
  currently operating at radio wavelengths.

Title: Stellar Spectroscopy During Exoplanet Transits: Dissecting
    Fine Structure Across Stellar Surfaces
Authors: Dravins, Dainis; Ludwig, Hans-Gunter; Dahlen, Erik; Pazira,
   Hiva
Bibcode: 2015csss...18..853D
Altcode: 2014arXiv1408.1402D
  Differential spectroscopy during exoplanet transits permits to
  reconstruct spectra of small stellar surface portions that successively
  become hidden behind the planet. The center-to-limb behavior of stellar
  line shapes, asymmetries and wavelength shifts will enable detailed
  tests of 3-dimensional hydrodynamic models of stellar atmospheres,
  such that are required for any precise determination of abundances or
  seismic properties. Such models can now be computed for widely different
  stars but have been feasible to test in detail only for the Sun with
  its resolved surface structure. Although very high quality spectra are
  required, already current data permit reconstructions of line profiles
  in the brightest transit host stars such as HD 209458 (G0 V).

Title: Stellar intensity interferometry over kilometer baselines:
    laboratory simulation of observations with the Cherenkov Telescope
    Array
Authors: Dravins, Dainis; Lagadec, Tiphaine
Bibcode: 2014SPIE.9146E..0ZD
Altcode: 2014arXiv1407.5993D
  A long-held astronomical vision is to realize diffraction-limited
  optical aperture synthesis over kilometer baselines. This will enable
  imaging of stellar surfaces and their environments, show their evolution
  over time, and reveal interactions of stellar winds and gas flows in
  binary star systems. An opportunity is now opening up with the large
  telescope arrays primarily erected for measuring Cherenkov light in
  air induced by gamma rays. With suitable software, such telescopes
  could be electronically connected and used also for intensity
  interferometry. With no optical connection between the telescopes,
  the error budget is set by the electronic time resolution of a few
  nanoseconds. Corresponding light-travel distances are on the order of
  one meter, making the method practically insensitive to atmospheric
  turbulence or optical imperfections, permitting both very long baselines
  and observing at short optical wavelengths. Theoretical modeling has
  shown how stellar surface images can be retrieved from such observations
  and here we report on experimental simulations. In an optical
  laboratory, artificial stars (single and double, round and elliptic)
  are observed by an array of telescopes. Using high-speed photon-counting
  solid-state detectors and real-time electronics, intensity fluctuations
  are cross correlated between up to a hundred baselines between pairs
  of telescopes, producing maps of the second-order spatial coherence
  across the interferometric Fourier-transform plane. These experiments
  serve to verify the concepts and to optimize the instrumentation and
  observing procedures for future observations with (in particular) CTA,
  the Cherenkov Telescope Array, aiming at order-of-magnitude improvements
  of the angular resolution in optical astronomy.

Title: Intensity Interferometry with Cherenkov Telescope Arrays:
    Prospects for submilliarcsecond optical imaging
Authors: Dravins, D.
Bibcode: 2014ipco.conf...19D
Altcode:
  Intensity interferometry measures the second-order coherence
  of light. Very rapid (nanosecond) fluctuations are correlated
  between separate telescopes, without any optical connection. This
  makes the method insensitive to atmospheric turbulence and optical
  imperfections, permitting observations over long baselines, and at
  short wavelengths. The required large telescopes are becoming available
  as those primarily erected to study gamma rays: the planned Cherenkov
  Telescope Array (https://www.cta-observatory.org/) envisions many tens
  of telescopes distributed over a few square km. Digital signal handling
  enables very many baselines to be simultaneously synthesized between
  many pairs of telescopes, while stars may be tracked across the sky
  with electronic time delays, synthesizing an optical interferometer
  in software. Simulations indicate limiting magnitudes around m(v)=8,
  reaching a resolution of 30 microarcseconds in the violet. Since
  intensity interferometry provides only the modulus (not phase) of any
  spatial frequency component of the source image, image reconstruction
  requires phase retrieval techniques. As shown in simulations, full
  two-dimensional images can be retrieved, provided there is an extensive
  coverage of the (u,v)-plane, such as will be available once the number
  of telescopes reaches numbers on the order of ten.

Title: A Community Science Case for E-ELT HIRES
Authors: Maiolino, R.; Haehnelt, M.; Murphy, M. T.; Queloz, D.;
   Origlia, L.; Alcala, J.; Alibert, Y.; Amado, P. J.; Allende Prieto, C.;
   Ammler-von Eiff, M.; Asplund, M.; Barstow, M.; Becker, G.; Bonfils, X.;
   Bouchy, F.; Bragaglia, A.; Burleigh, M. R.; Chiavassa, A.; Cimatti,
   D. A.; Cirasuolo, M.; Cristiani, S.; D'Odorico, V.; Dravins, D.;
   Emsellem, E.; Farihi, J.; Figueira, P.; Fynbo, J.; Gansicke, B. T.;
   Gillon, M.; Gustafsson, B.; Hill, V.; Israelyan, G.; Korn, A.; Larsen,
   S.; De Laverny, P.; Liske, J.; Lovis, C.; Marconi, A.; Martins, C.;
   Molaro, P.; Nisini, B.; Oliva, E.; Petitjean, P.; Pettini, M.; Recio
   Blanco, A.; Rebolo, R.; Reiners, A.; Rodriguez-Lopez, C.; Ryde, N.;
   Santos, N. C.; Savaglio, S.; Snellen, I.; Strassmeier, K.; Tanvir, N.;
   Testi, L.; Tolstoy, E.; Triaud, A.; Vanzi, L.; Viel, M.; Volonteri, M.
Bibcode: 2013arXiv1310.3163M
Altcode:
  Building on the experience of the high-resolution community with the
  suite of VLT high-resolution spectrographs, which has been tremendously
  successful, we outline here the (science) case for a high-fidelity,
  high-resolution spectrograph with wide wavelength coverage at the
  E-ELT. Flagship science drivers include: the study of exo-planetary
  atmospheres with the prospect of the detection of signatures of life
  on rocky planets; the chemical composition of planetary debris on the
  surface of white dwarfs; the spectroscopic study of protoplanetary and
  proto-stellar disks; the extension of Galactic archaeology to the Local
  Group and beyond; spectroscopic studies of the evolution of galaxies
  with samples that, unlike now, are no longer restricted to strongly
  star forming and/or very massive galaxies; the unraveling of the
  complex roles of stellar and AGN feedback; the study of the chemical
  signatures imprinted by population III stars on the IGM during the
  epoch of reionization; the exciting possibility of paradigm-changing
  contributions to fundamental physics. The requirements of these science
  cases can be met by a stable instrument with a spectral resolution
  of R~100,000 and broad, simultaneous spectral coverage extending
  from 370nm to 2500nm. Most science cases do not require spatially
  resolved information, and can be pursued in seeing-limited mode,
  although some of them would benefit by the E-ELT diffraction limited
  resolution. Some multiplexing would also be beneficial for some of
  the science cases. (Abridged)

Title: CTA contributions to the 33rd International Cosmic Ray
    Conference (ICRC2013)
Authors: CTA Consortium, The; :; Abril, O.; Acharya, B. S.; Actis, M.;
   Agnetta, G.; Aguilar, J. A.; Aharonian, F.; Ajello, M.; Akhperjanian,
   A.; Alcubierre, M.; Aleksic, J.; Alfaro, R.; Aliu, E.; Allafort,
   A. J.; Allan, D.; Allekotte, I.; Aloisio, R.; Amato, E.; Ambrosi,
   G.; Ambrosio, M.; Anderson, J.; Angüner, E. O.; Antonelli, L. A.;
   Antonuccio, V.; Antonucci, M.; Antoranz, P.; Aravantinos, A.; Argan,
   A.; Arlen, T.; Aramo, C.; Armstrong, T.; Arnaldi, H.; Arrabito, L.;
   Asano, K.; Ashton, T.; Asorey, H. G.; Aune, T.; Awane, Y.; Baba, H.;
   Babic, A.; Baby, N.; Bähr, J.; Bais, A.; Baixeras, C.; Bajtlik, S.;
   Balbo, M.; Balis, D.; Balkowski, C.; Ballet, J.; Bamba, A.; Bandiera,
   R.; Barber, A.; Barbier, C.; Barceló, M.; Barnacka, A.; Barnstedt,
   J.; Barres de Almeida, U.; Barrio, J. A.; Basili, A.; Basso, S.;
   Bastieri, D.; Bauer, C.; Baushev, A.; Becciani, U.; Becerra, J.;
   Becerra, J.; Becherini, Y.; Bechtol, K. C.; Becker Tjus, J.; Beckmann,
   V.; Bednarek, W.; Behera, B.; Belluso, M.; Benbow, W.; Berdugo, J.;
   Berge, D.; Berger, K.; Bernard, F.; Bernardino, T.; Bernlöhr, K.;
   Bertucci, B.; Bhat, N.; Bhattacharyya, S.; Biasuzzi, B.; Bigongiari,
   C.; Biland, A.; Billotta, S.; Bird, T.; Birsin, E.; Bissaldi, E.;
   Biteau, J.; Bitossi, M.; Blake, S.; Blanch Bigas, O.; Blasi, P.;
   Bobkov, A.; Boccone, V.; Böttcher, M.; Bogacz, L.; Bogart, J.;
   Bogdan, M.; Boisson, C.; Boix Gargallo, J.; Bolmont, J.; Bonanno,
   G.; Bonardi, A.; Bonev, T.; Bonifacio, P.; Bonnoli, G.; Bordas,
   P.; Borgland, A.; Borkowski, J.; Bose, R.; Botner, O.; Bottani, A.;
   Bouchet, L.; Bourgeat, M.; Boutonnet, C.; Bouvier, A.; Brau-Nogué, S.;
   Braun, I.; Bretz, T.; Briggs, M.; Brigida, M.; Bringmann, T.; Britto,
   R.; Brook, P.; Brun, P.; Brunetti, L.; Bruno, P.; Bucciantini, N.;
   Buanes, T.; Buckley, J.; Bühler, R.; Bugaev, V.; Bulgarelli, A.;
   Bulik, T.; Busetto, G.; Buson, S.; Byrum, K.; Cailles, M.; Cameron,
   R.; Camprecios, J.; Canestrari, R.; Cantu, S.; Capalbi, M.; Caraveo,
   P.; Carmona, E.; Carosi, A.; Carosi, R.; Carr, J.; Carter, J.;
   Carton, P. -H.; Caruso, R.; Casanova, S.; Cascone, E.; Casiraghi, M.;
   Castellina, A.; Catalano, O.; Cavazzani, S.; Cazaux, S.; Cerchiara,
   P.; Cerruti, M.; Chabanne, E.; Chadwick, P.; Champion, C.; Chaves,
   R.; Cheimets, P.; Chen, A.; Chiang, J.; Chiappetti, L.; Chikawa, M.;
   Chitnis, V. R.; Chollet, F.; Christof, A.; Chudoba, J.; Cieślar, M.;
   Cillis, A.; Cilmo, M.; Codino, A.; Cohen-Tanugi, J.; Colafrancesco,
   S.; Colin, P.; Colome, J.; Colonges, S.; Compin, M.; Conconi, P.;
   Conforti, V.; Connaughton, V.; Conrad, J.; Contreras, J. L.; Coppi,
   P.; Coridian, J.; Corona, P.; Corti, D.; Cortina, J.; Cossio, L.;
   Costa, A.; Costantini, H.; Cotter, G.; Courty, B.; Couturier, S.;
   Covino, S.; Crimi, G.; Criswell, S. J.; Croston, J.; Cusumano, G.;
   Dafonseca, M.; Dale, O.; Daniel, M.; Darling, J.; Davids, I.; Dazzi,
   F.; de Angelis, A.; De Caprio, V.; De Frondat, F.; de Gouveia Dal Pino,
   E. M.; de la Calle, I.; De La Vega, G. A.; de los Reyes Lopez, R.;
   de Lotto, B.; De Luca, A.; de Naurois, M.; de Oliveira, Y.; de Oña
   Wilhelmi, E.; de Palma, F.; de Souza, V.; Decerprit, G.; Decock, G.;
   Deil, C.; Delagnes, E.; Deleglise, G.; Delgado, C.; della Volpe, D.;
   Demange, P.; Depaola, G.; Dettlaff, A.; Di Girolamo, T.; Di Giulio,
   C.; Di Paola, A.; Di Pierro, F.; di Sciascio, G.; Díaz, C.; Dick, J.;
   Dickherber, R.; Dickinson, H.; Diez-Blanco, V.; Digel, S.; Dimitrov,
   D.; Disset, G.; Djannati-Ataï, A.; Doert, M.; Dohmke, M.; Domainko,
   W.; Dominis Prester, D.; Donat, A.; Dorner, D.; Doro, M.; Dournaux,
   J. -L.; Drake, G.; Dravins, D.; Drury, L.; Dubois, F.; Dubois, R.;
   Dubus, G.; Dufour, C.; Dumas, D.; Dumm, J.; Durand, D.; Dwarkadas, V.;
   Dyks, J.; Dyrda, M.; Ebr, J.; Edy, E.; Egberts, K.; Eger, P.; Einecke,
   S.; Eleftheriadis, C.; Elles, S.; Emmanoulopoulos, D.; Engelhaupt,
   D.; Enomoto, R.; Ernenwein, J. -P.; Errando, M.; Etchegoyen, A.;
   Evans, P. A.; Falcone, A.; Faltenbacher, A.; Fantinel, D.; Farakos,
   K.; Farnier, C.; Farrell, E.; Fasola, G.; Favill, B. W.; Fede,
   E.; Federici, S.; Fegan, S.; Feinstein, F.; Ferenc, D.; Ferrando,
   P.; Fesquet, M.; Fetfatzis, P.; Fiasson, A.; Fillin-Martino, E.;
   Fink, D.; Finley, C.; Finley, J. P.; Fiorini, M.; Firpo Curcoll,
   R.; Flandrini, E.; Fleischhack, H.; Flores, H.; Florin, D.; Focke,
   W.; Föhr, C.; Fokitis, E.; Font, L.; Fontaine, G.; Fornasa, M.;
   Förster, A.; Fortson, L.; Fouque, N.; Franckowiak, A.; Franco, F. J.;
   Frankowski, A.; Fransson, C.; Fraser, G. W.; Frei, R.; Fresnillo, L.;
   Fruck, C.; Fugazza, D.; Fujita, Y.; Fukazawa, Y.; Fukui, Y.; Funk,
   S.; Gäbele, W.; Gabici, S.; Gabriele, R.; Gadola, A.; Galante, N.;
   Gall, D.; Gallant, Y.; Gámez-García, J.; Garczarczyk, M.; García,
   B.; Garcia López, R.; Gardiol, D.; Gargano, F.; Garrido, D.; Garrido,
   L.; Gascon, D.; Gaug, M.; Gaweda, J.; Gebremedhin, L.; Geffroy, N.;
   Gerard, L.; Ghedina, A.; Ghigo, M.; Ghislain, P.; Giannakaki, E.;
   Gianotti, F.; Giarrusso, S.; Giavitto, G.; Giebels, B.; Giglietto,
   N.; Gika, V.; Giomi, M.; Giommi, P.; Giordano, F.; Girard, N.; Giro,
   E.; Giuliani, A.; Glanzman, T.; Glicenstein, J. -F.; Godinovic, N.;
   Golev, V.; Gomez Berisso, M.; Gómez-Ortega, J.; Gonzalez, M. M.;
   González, A.; González, F.; González Muñoz, A.; Gothe, K. S.;
   Grabarczyk, T.; Gougerot, M.; Graciani, R.; Grandi, P.; Grañena,
   F.; Granot, J.; Grasseau, G.; Gredig, R.; Green, A.; Greenshaw, T.;
   Grégoire, T.; Grillo, A.; Grimm, O.; Grondin, M. -H.; Grube, J.;
   Grudzinska, M.; Gruev, V.; Grünewald, S.; Grygorczuk, J.; Guarino,
   V.; Gunji, S.; Gyuk, G.; Hadasch, D.; Hagedorn, A.; Hagiwara, R.;
   Hahn, J.; Hakansson, N.; Hallgren, A.; Hamer Heras, N.; Hara, S.;
   Hardcastle, M. J.; Harezlak, D.; Harris, J.; Hassan, T.; Hatanaka,
   K.; Haubold, T.; Haupt, A.; Hayakawa, T.; Hayashida, M.; Heller, R.;
   Henault, F.; Henri, G.; Hermann, G.; Hermel, R.; Herrero, A.; Hervet,
   O.; Hidaka, N.; Hinton, J. A.; Hirotani, K.; Hoffmann, D.; Hofmann,
   W.; Hofverberg, P.; Holder, J.; Hörandel, J. R.; Horns, D.; Horville,
   D.; Houles, J.; Hrabovsky, M.; Hrupec, D.; Huan, H.; Huber, B.; Huet,
   J. -M.; Hughes, G.; Humensky, T. B.; Huovelin, J.; Huppert, J. -F.;
   Ibarra, A.; Ikawa, D.; Illa, J. M.; Impiombato, D.; Incorvaia, S.;
   Inoue, S.; Inoue, Y.; Iocco, F.; Ioka, K.; Israel, G. L.; Jablonski,
   C.; Jacholkowska, A.; Jacquemier, J.; Jamrozy, M.; Janiak, M.; Jean,
   P.; Jeanney, C.; Jimenez, J. J.; Jogler, T.; Johnson, C.; Johnson,
   T.; Journet, L.; Juffroy, C.; Jung, I.; Kaaret, P.; Kabuki, S.;
   Kagaya, M.; Kakuwa, J.; Kalkuhl, C.; Kankanyan, R.; Karastergiou,
   A.; Kärcher, K.; Karczewski, M.; Karkar, S.; Kasperek, J.; Kastana,
   D.; Katagiri, H.; Kataoka, J.; Katarzyński, K.; Katz, U.; Kawanaka,
   N.; Kazanas, D.; Kelley-Hoskins, N.; Kellner-Leidel, B.; Kelly, H.;
   Kendziorra, E.; Khélifi, B.; Kieda, D. B.; Kifune, T.; Kihm, T.;
   Kishimoto, T.; Kitamoto, K.; Kluźniak, W.; Knapic, C.; Knapp, J.;
   Knödlseder, J.; Köck, F.; Kocot, J.; Kodani, K.; Köhne, J. -H.;
   Kohri, K.; Kokkotas, K.; Kolitzus, D.; Komin, N.; Kominis, I.; Konno,
   Y.; Köppel, H.; Korohoda, P.; Kosack, K.; Koss, G.; Kossakowski,
   R.; Koul, R.; Kowal, G.; Koyama, S.; Kozioł, J.; Krähenbühl, T.;
   Krause, J.; Krawzcynski, H.; Krennrich, F.; Krepps, A.; Kretzschmann,
   A.; Krobot, R.; Krueger, P.; Kubo, H.; Kudryavtsev, V. A.; Kushida,
   J.; Kuznetsov, A.; La Barbera, A.; La Palombara, N.; La Parola, V.;
   La Rosa, G.; Lacombe, K.; Lamanna, G.; Lande, J.; Languignon, D.;
   Lapington, J. S.; Laporte, P.; Laurent, B.; Lavalley, C.; Le Flour,
   T.; Le Padellec, A.; Lee, S. -H.; Lee, W. H.; Lefèvre, J. -P.; Leich,
   H.; Leigui de Oliveira, M. A.; Lelas, D.; Lenain, J. -P.; Leoni,
   R.; Leopold, D. J.; Lerch, T.; Lessio, L.; Leto, G.; Lieunard, B.;
   Lieunard, S.; Lindemann, R.; Lindfors, E.; Liolios, A.; Lipniacka,
   A.; Lockart, H.; Lohse, T.; Lombardi, S.; Longo, F.; Lopatin, A.;
   Lopez, M.; López-Coto, R.; López-Oramas, A.; Lorca, A.; Lorenz,
   E.; Louis, F.; Lubinski, P.; Lucarelli, F.; Lüdecke, H.; Ludwin, J.;
   Luque-Escamilla, P. L.; Lustermann, W.; Luz, O.; Lyard, E.; Maccarone,
   M. C.; Maccarone, T. J.; Madejski, G. M.; Madhavan, A.; Mahabir, M.;
   Maier, G.; Majumdar, P.; Malaguti, G.; Malaspina, G.; Maltezos, S.;
   Manalaysay, A.; Mancilla, A.; Mandat, D.; Maneva, G.; Mangano, A.;
   Manigot, P.; Mannheim, K.; Manthos, I.; Maragos, N.; Marcowith, A.;
   Mariotti, M.; Marisaldi, M.; Markoff, S.; Marszałek, A.; Martens,
   C.; Martí, J.; Martin, J. -M.; Martin, P.; Martínez, G.; Martínez,
   F.; Martínez, M.; Massaro, F.; Masserot, A.; Mastichiadis, A.;
   Mathieu, A.; Matsumoto, H.; Mattana, F.; Mattiazzo, S.; Maurer, A.;
   Maurin, G.; Maxfield, S.; Maya, J.; Mazin, D.; Mc Comb, L.; McCann,
   A.; McCubbin, N.; McHardy, I.; McKay, R.; Meagher, K.; Medina, C.;
   Melioli, C.; Melkumyan, D.; Melo, D.; Mereghetti, S.; Mertsch, P.;
   Meucci, M.; Meyer, M.; Michałowski, J.; Micolon, P.; Mihailidis,
   A.; Mineo, T.; Minuti, M.; Mirabal, N.; Mirabel, F.; Miranda, J. M.;
   Mirzoyan, R.; Mistò, A.; Mizuno, T.; Moal, B.; Moderski, R.; Mognet,
   I.; Molinari, E.; Molinaro, M.; Montaruli, T.; Monte, C.; Monteiro, I.;
   Moore, P.; Moralejo Olaizola, A.; Mordalska, M.; Morello, C.; Mori,
   K.; Morlino, G.; Morselli, A.; Mottez, F.; Moudden, Y.; Moulin, E.;
   Mrusek, I.; Mukherjee, R.; Munar-Adrover, P.; Muraishi, H.; Murase, K.;
   StJ. Murphy, A.; Nagataki, S.; Naito, T.; Nakajima, D.; Nakamori, T.;
   Nakayama, K.; Naumann, C.; Naumann, D.; Naumann-Godo, M.; Nayman, P.;
   Nedbal, D.; Neise, D.; Nellen, L.; Neronov, A.; Neustroev, V.; Neyroud,
   N.; Nicastro, L.; Nicolau-Kukliński, J.; Niedźwiecki, A.; Niemiec,
   J.; Nieto, D.; Nikolaidis, A.; Nishijima, K.; Nishikawa, K. -I.;
   Noda, K.; Nolan, S.; Northrop, R.; Nosek, D.; Nowak, N.; Nozato, A.;
   Oakes, L.; O'Brien, P. T.; Ohira, Y.; Ohishi, M.; Ohm, S.; Ohoka, H.;
   Okuda, T.; Okumura, A.; Olive, J. -F.; Ong, R. A.; Orito, R.; Orr, M.;
   Osborne, J. P.; Ostrowski, M.; Otero, L. A.; Otte, N.; Ovcharov, E.;
   Oya, I.; Ozieblo, A.; Padilla, L.; Pagano, I.; Paiano, S.; Paillot, D.;
   Paizis, A.; Palanque, S.; Palatka, M.; Pallota, J.; Palatiello, M.;
   Panagiotidis, K.; Panazol, J. -L.; Paneque, D.; Panter, M.; Panzera,
   M. R.; Paoletti, R.; Papayannis, A.; Papyan, G.; Paredes, J. M.;
   Pareschi, G.; Parraud, J. -M.; Parsons, D.; Pauletta, G.; Paz Arribas,
   M.; Pech, M.; Pedaletti, G.; Pelassa, V.; Pelat, D.; Perez, M. d. C.;
   Persic, M.; Petrucci, P. -O.; Peyaud, B.; Pichel, A.; Pieloth, D.;
   Pierre, E.; Pita, S.; Pivato, G.; Pizzolato, F.; Platino, M.; Platos,
   Ł.; Platzer, R.; Podkladkin, S.; Pogosyan, L.; Pohl, M.; Pojmanski,
   G.; Ponz, J. D.; Potter, W.; Poutanen, J.; Prandini, E.; Prast,
   J.; Preece, R.; Profeti, F.; Prokoph, H.; Prouza, M.; Proyetti, M.;
   Puerto-Giménez, I.; Pühlhofer, G.; Puljak, I.; Punch, M.; Pyzioł,
   R.; Quel, E. J.; Quesada, J.; Quinn, J.; Quirrenbach, A.; Racero, E.;
   Rainò, S.; Rajda, P. J.; Rameez, M.; Ramon, P.; Rando, R.; Rannot,
   R. C.; Rataj, M.; Raue, M.; Ravignani, D.; Reardon, P.; Reimann,
   O.; Reimer, A.; Reimer, O.; Reitberger, K.; Renaud, M.; Renner,
   S.; Reville, B.; Rhode, W.; Ribó, M.; Ribordy, M.; Richards, G.;
   Richer, M. G.; Rico, J.; Ridky, J.; Rieger, F.; Ringegni, P.; Ripken,
   J.; Ristori, P. R.; Rivière, A.; Rivoire, S.; Rob, L.; Rodeghiero,
   G.; Roeser, U.; Rohlfs, R.; Rojas, G.; Romano, P.; Romaszkan, W.;
   Romero, G. E.; Rosen, S. R.; Rosier Lees, S.; Ross, D.; Rouaix, G.;
   Rousselle, J.; Rousselle, S.; Rovero, A. C.; Roy, F.; Royer, S.;
   Rudak, B.; Rulten, C.; Rupiński, M.; Russo, F.; Ryde, F.; Saavedra,
   O.; Sacco, B.; Saemann, E. O.; Saggion, A.; Sahakian, V.; Saito, K.;
   Saito, T.; Saito, Y.; Sakaki, N.; Sakonaka, R.; Salini, A.; Sanchez,
   F.; Sanchez-Conde, M.; Sandoval, A.; Sandaker, H.; Sant'Ambrogio, E.;
   Santangelo, A.; Santos, E. M.; Sanuy, A.; Sapozhnikov, L.; Sarkar,
   S.; Sartore, N.; Sasaki, H.; Satalecka, K.; Sawada, M.; Scalzotto, V.;
   Scapin, V.; Scarcioffolo, M.; Schafer, J.; Schanz, T.; Schlenstedt,
   S.; Schlickeiser, R.; Schmidt, T.; Schmoll, J.; Schovanek, P.;
   Schroedter, M.; Schubert, A.; Schultz, C.; Schultze, J.; Schulz,
   A.; Schure, K.; Schussler, F.; Schwab, T.; Schwanke, U.; Schwarz,
   J.; Schwarzburg, S.; Schweizer, T.; Schwemmer, S.; Schwendicke, U.;
   Schwerdt, C.; Segreto, A.; Seiradakis, J. -H.; Sembroski, G. H.;
   Servillat, M.; Seweryn, K.; Sharma, M.; Shayduk, M.; Shellard,
   R. C.; Shi, J.; Shibata, T.; Shibuya, A.; Shore, S.; Shum, E.;
   Sideras-Haddad, E.; Sidoli, L.; Sidz, M.; Sieiro, J.; Sikora, M.;
   Silk, J.; Sillanpää, A.; Singh, B. B.; Sironi, G.; Sitarek, J.;
   Skole, C.; Smareglia, R.; Smith, A.; Smith, D.; Smith, J.; Smith,
   N.; Sobczyńska, D.; Sol, H.; Sottile, G.; Sowiński, M.; Spanier,
   F.; Spiga, D.; Spyrou, S.; Stamatescu, V.; Stamerra, A.; Starling,
   R. L. C.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Steiner, S.;
   Stella, C.; Stergioulas, N.; Sternberger, R.; Sterzel, M.; Stinzing,
   F.; Stodulski, M.; Stolarczyk, Th.; Straumann, U.; Strazzeri, E.;
   Stringhetti, L.; Suarez, A.; Suchenek, M.; Sugawara, R.; Sulanke,
   K. -H.; Sun, S.; Supanitsky, A. D.; Suric, T.; Sutcliffe, P.; Sykes,
   J. M.; Szanecki, M.; Szepieniec, T.; Szostek, A.; Tagliaferri, G.;
   Tajima, H.; Takahashi, H.; Takahashi, K.; Takalo, L.; Takami, H.;
   Talbot, G.; Tammi, J.; Tanaka, M.; Tanaka, S.; Tasan, J.; Tavani,
   M.; Tavernet, J. -P.; Tejedor, L. A.; Telezhinsky, I.; Temnikov, P.;
   Tenzer, C.; Terada, Y.; Terrier, R.; Teshima, M.; Testa, V.; Tezier,
   D.; Thayer, J.; Thuermann, D.; Tibaldo, L.; Tibaldo, L.; Tibolla,
   O.; Tiengo, A.; Timpanaro, M. C.; Tluczykont, M.; Todero Peixoto,
   C. J.; Tokanai, F.; Tokarz, M.; Toma, K.; Tonachini, A.; Torii, K.;
   Tornikoski, M.; Torres, D. F.; Torres, M.; Toscano, S.; Toso, G.;
   Tosti, G.; Totani, T.; Toussenel, F.; Tovmassian, G.; Travnicek, P.;
   Treves, A.; Trifoglio, M.; Troyano, I.; Tsinganos, K.; Ueno, H.; Umana,
   G.; Umehara, K.; Upadhya, S. S.; Usher, T.; Uslenghi, M.; Vagnetti, F.;
   Valdes-Galicia, J. F.; Vallania, P.; Vallejo, G.; van Driel, W.; van
   Eldik, C.; Vandenbrouke, J.; Vanderwalt, J.; Vankov, H.; Vasileiadis,
   G.; Vassiliev, V.; Veberic, D.; Vegas, I.; Vercellone, S.; Vergani,
   S.; Verzi, V.; Vettolani, G. P.; Veyssière, C.; Vialle, J. P.;
   Viana, A.; Videla, M.; Vigorito, C.; Vincent, P.; Vincent, S.; Vink,
   J.; Vlahakis, N.; Vlahos, L.; Vogler, P.; Voisin, V.; Vollhardt, A.;
   von Gunten, H. -P.; Vorobiov, S.; Vuerli, C.; Waegebaert, V.; Wagner,
   R.; Wagner, R. G.; Wagner, S.; Wakely, S. P.; Walter, R.; Walther,
   T.; Warda, K.; Warwick, R. S.; Wawer, P.; Wawrzaszek, R.; Webb, N.;
   Wegner, P.; Weinstein, A.; Weitzel, Q.; Welsing, R.; Werner, M.;
   Wetteskind, H.; White, R. J.; Wierzcholska, A.; Wiesand, S.; Wilhelm,
   A.; Wilkinson, M. I.; Williams, D. A.; Willingale, R.; Winde, M.;
   Winiarski, K.; Wischnewski, R.; Wiśniewski, Ł.; Wojcik, P.; Wood,
   M.; Wörnlein, A.; Xiong, Q.; Yadav, K. K.; Yamamoto, H.; Yamamoto,
   T.; Yamazaki, R.; Yanagita, S.; Yebras, J. M.; Yelos, D.; Yoshida,
   A.; Yoshida, T.; Yoshikoshi, T.; Yu, P.; Zabalza, V.; Zacharias, M.;
   Zajczyk, A.; Zampieri, L.; Zanin, R.; Zdziarski, A.; Zech, A.; Zhao,
   A.; Zhou, X.; Zietara, K.; Ziolkowski, J.; Ziółkowski, P.; Zitelli,
   V.; Zurbach, C.; Zychowski, P.
Bibcode: 2013arXiv1307.2232C
Altcode:
  Compilation of CTA contributions to the proceedings of the 33rd
  International Cosmic Ray Conference (ICRC2013), which took place in
  2-9 July, 2013, in Rio de Janeiro, Brazil

Title: Introducing the CTA concept
Authors: Acharya, B. S.; Actis, M.; Aghajani, T.; Agnetta, G.;
   Aguilar, J.; Aharonian, F.; Ajello, M.; Akhperjanian, A.; Alcubierre,
   M.; Aleksić, J.; Alfaro, R.; Aliu, E.; Allafort, A. J.; Allan, D.;
   Allekotte, I.; Amato, E.; Anderson, J.; Angüner, E. O.; Antonelli,
   L. A.; Antoranz, P.; Aravantinos, A.; Arlen, T.; Armstrong, T.;
   Arnaldi, H.; Arrabito, L.; Asano, K.; Ashton, T.; Asorey, H. G.; Awane,
   Y.; Baba, H.; Babic, A.; Baby, N.; Bähr, J.; Bais, A.; Baixeras, C.;
   Bajtlik, S.; Balbo, M.; Balis, D.; Balkowski, C.; Bamba, A.; Bandiera,
   R.; Barber, A.; Barbier, C.; Barceló, M.; Barnacka, A.; Barnstedt, J.;
   Barres de Almeida, U.; Barrio, J. A.; Basili, A.; Basso, S.; Bastieri,
   D.; Bauer, C.; Baushev, A.; Becerra, J.; Becherini, Y.; Bechtol, K. C.;
   Becker Tjus, J.; Beckmann, V.; Bednarek, W.; Behera, B.; Belluso,
   M.; Benbow, W.; Berdugo, J.; Berger, K.; Bernard, F.; Bernardino, T.;
   Bernlöhr, K.; Bhat, N.; Bhattacharyya, S.; Bigongiari, C.; Biland,
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   Manalaysay, A.; Mancilla, A.; Mandat, D.; Maneva, G.; Mangano, A.;
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   Mariotti, M.; Marisaldi, M.; Markoff, S.; Marszałek, A.; Martens, C.;
   Martí, J.; Martin, J. -M.; Martin, P.; Martínez, G.; Martínez, F.;
   Martínez, M.; Masserot, A.; Mastichiadis, A.; Mathieu, A.; Matsumoto,
   H.; Mattana, F.; Mattiazzo, S.; Maurin, G.; Maxfield, S.; Maya, J.;
   Mazin, D.; Mc Comb, L.; McCubbin, N.; McHardy, I.; McKay, R.; Medina,
   C.; Melioli, C.; Melkumyan, D.; Mereghetti, S.; Mertsch, P.; Meucci,
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   Zitelli, V.; Zurbach, C.; Żychowski, P.; CTA Consortium
Bibcode: 2013APh....43....3A
Altcode: 2013APh....43....3C
  The Cherenkov Telescope Array (CTA) is a new observatory for very
  high-energy (VHE) gamma rays. CTA has ambitions science goals, for which
  it is necessary to achieve full-sky coverage, to improve the sensitivity
  by about an order of magnitude, to span about four decades of energy,
  from a few tens of GeV to above 100 TeV with enhanced angular and energy
  resolutions over existing VHE gamma-ray observatories. An international
  collaboration has formed with more than 1000 members from 27 countries
  in Europe, Asia, Africa and North and South America. In 2010 the CTA
  Consortium completed a Design Study and started a three-year Preparatory
  Phase which leads to production readiness of CTA in 2014. In this paper
  we introduce the science goals and the concept of CTA, and provide an
  overview of the project.

Title: Optical intensity interferometry with the Cherenkov Telescope
    Array
Authors: Dravins, Dainis; LeBohec, Stephan; Jensen, Hannes; Nuñez,
   Paul D.; CTA Consortium
Bibcode: 2013APh....43..331D
Altcode: 2012arXiv1204.3624D
  With its unprecedented light-collecting area for night-sky observations,
  the Cherenkov Telescope Array (CTA) holds great potential for also
  optical stellar astronomy, in particular as a multi-element intensity
  interferometer for realizing imaging with sub-milliarcsecond angular
  resolution. Such an order-of-magnitude increase of the spatial
  resolution achieved in optical astronomy will reveal the surfaces of
  rotationally flattened stars with structures in their circumstellar
  disks and winds, or the gas flows between close binaries. Image
  reconstruction is feasible from the second-order coherence of light,
  measured as the temporal correlations of arrival times between photons
  recorded in different telescopes. This technique (once pioneered by
  Hanbury Brown and Twiss) connects telescopes only with electronic
  signals and is practically insensitive to atmospheric turbulence
  and to imperfections in telescope optics. Detector and telescope
  requirements are very similar to those for imaging air Cherenkov
  observatories, the main difference being the signal processing
  (calculating cross correlations between single camera pixels
  in pairs of telescopes). Observations of brighter stars are not
  limited by sky brightness, permitting efficient CTA use during also
  bright-Moon periods. While other concepts have been proposed to realize
  kilometer-scale optical interferometers of conventional amplitude
  (phase-) type, both in space and on the ground, their complexity places
  them much further into the future than CTA, which thus could become
  the first kilometer-scale optical imager in astronomy.

Title: Stellar intensity interferometry: Prospects for
    sub-milliarcsecond optical imaging
Authors: Dravins, Dainis; LeBohec, Stephan; Jensen, Hannes; Nuñez,
   Paul D.
Bibcode: 2012NewAR..56..143D
Altcode: 2012arXiv1207.0808D
  Using kilometric arrays of air Cherenkov telescopes at short
  wavelengths, intensity interferometry may increase the spatial
  resolution achieved in optical astronomy by an order of magnitude,
  enabling images of rapidly rotating hot stars with structures in
  their circumstellar disks and winds, or mapping out patterns of
  nonradial pulsations across stellar surfaces. Intensity interferometry
  (once pioneered by Hanbury Brown and Twiss) connects telescopes only
  electronically, and is practically insensitive to atmospheric turbulence
  and optical imperfections, permitting observations over long baselines
  and through large airmasses, also at short optical wavelengths. The
  required large telescopes (∼10 m) with very fast detectors (∼ns)
  are becoming available as the arrays primarily erected to measure
  Cherenkov light emitted in air by particle cascades initiated by
  energetic gamma rays. Planned facilities (e.g., CTA, Cherenkov Telescope
  Array) envision many tens of telescopes distributed over a few square
  km. Digital signal handling enables very many baselines (from tens of
  meters to over a kilometer) to be simultaneously synthesized between
  many pairs of telescopes, while stars may be tracked across the sky with
  electronic time delays, in effect synthesizing an optical interferometer
  in software. Simulated observations indicate limiting magnitudes around
  m<SUB>V</SUB> = 8, reaching angular resolutions ∼30 μarcsec in the
  violet. The signal-to-noise ratio favors high-temperature sources and
  emission-line structures, and is independent of the optical passband,
  be it a single spectral line or the broad spectral continuum. Intensity
  interferometry directly provides the modulus (but not phase) of any
  spatial frequency component of the source image; for this reason a
  full image reconstruction requires phase retrieval techniques. This is
  feasible if sufficient coverage of the interferometric (u, v)-plane is
  available, as was verified through numerical simulations. Laboratory and
  field experiments are in progress; test telescopes have been erected,
  intensity interferometry has been achieved in the laboratory, and first
  full-scale tests of connecting large Cherenkov telescopes have been
  carried out. This paper reviews this interferometric method in view of
  the new possibilities offered by arrays of air Cherenkov telescopes,
  and outlines observational programs that should become realistic
  already in the rather near future.

Title: Design concepts for the Cherenkov Telescope Array CTA: an
    advanced facility for ground-based high-energy gamma-ray astronomy
Authors: Actis, M.; Agnetta, G.; Aharonian, F.; Akhperjanian,
   A.; Aleksić, J.; Aliu, E.; Allan, D.; Allekotte, I.; Antico, F.;
   Antonelli, L. A.; Antoranz, P.; Aravantinos, A.; Arlen, T.; Arnaldi,
   H.; Artmann, S.; Asano, K.; Asorey, H.; Bähr, J.; Bais, A.; Baixeras,
   C.; Bajtlik, S.; Balis, D.; Bamba, A.; Barbier, C.; Barceló, M.;
   Barnacka, A.; Barnstedt, J.; Barres de Almeida, U.; Barrio, J. A.;
   Basso, S.; Bastieri, D.; Bauer, C.; Becerra, J.; Becherini, Y.;
   Bechtol, K.; Becker, J.; Beckmann, V.; Bednarek, W.; Behera, B.;
   Beilicke, M.; Belluso, M.; Benallou, M.; Benbow, W.; Berdugo, J.;
   Berger, K.; Bernardino, T.; Bernlöhr, K.; Biland, A.; Billotta, S.;
   Bird, T.; Birsin, E.; Bissaldi, E.; Blake, S.; Blanch, O.; Bobkov,
   A. A.; Bogacz, L.; Bogdan, M.; Boisson, C.; Boix, J.; Bolmont,
   J.; Bonanno, G.; Bonardi, A.; Bonev, T.; Borkowski, J.; Botner, O.;
   Bottani, A.; Bourgeat, M.; Boutonnet, C.; Bouvier, A.; Brau-Nogué, S.;
   Braun, I.; Bretz, T.; Briggs, M. S.; Brun, P.; Brunetti, L.; Buckley,
   J. H.; Bugaev, V.; Bühler, R.; Bulik, T.; Busetto, G.; Buson, S.;
   Byrum, K.; Cailles, M.; Cameron, R.; Canestrari, R.; Cantu, S.;
   Carmona, E.; Carosi, A.; Carr, J.; Carton, P. H.; Casiraghi, M.;
   Castarede, H.; Catalano, O.; Cavazzani, S.; Cazaux, S.; Cerruti,
   B.; Cerruti, M.; Chadwick, P. M.; Chiang, J.; Chikawa, M.; Cieślar,
   M.; Ciesielska, M.; Cillis, A.; Clerc, C.; Colin, P.; Colomé, J.;
   Compin, M.; Conconi, P.; Connaughton, V.; Conrad, J.; Contreras, J. L.;
   Coppi, P.; Corlier, M.; Corona, P.; Corpace, O.; Corti, D.; Cortina,
   J.; Costantini, H.; Cotter, G.; Courty, B.; Couturier, S.; Covino,
   S.; Croston, J.; Cusumano, G.; Daniel, M. K.; Dazzi, F.; de Angelis,
   A.; de Cea Del Pozo, E.; de Gouveia Dal Pino, E. M.; de Jager, O.;
   de La Calle Pérez, I.; de La Vega, G.; de Lotto, B.; de Naurois,
   M.; de Oña Wilhelmi, E.; de Souza, V.; Decerprit, B.; Deil, C.;
   Delagnes, E.; Deleglise, G.; Delgado, C.; Dettlaff, T.; di Paolo,
   A.; di Pierro, F.; Díaz, C.; Dick, J.; Dickinson, H.; Digel, S. W.;
   Dimitrov, D.; Disset, G.; Djannati-Ataï, A.; Doert, M.; Domainko,
   W.; Dorner, D.; Doro, M.; Dournaux, J. -L.; Dravins, D.; Drury, L.;
   Dubois, F.; Dubois, R.; Dubus, G.; Dufour, C.; Durand, D.; Dyks,
   J.; Dyrda, M.; Edy, E.; Egberts, K.; Eleftheriadis, C.; Elles, S.;
   Emmanoulopoulos, D.; Enomoto, R.; Ernenwein, J. -P.; Errando, M.;
   Etchegoyen, A.; Falcone, A. D.; Farakos, K.; Farnier, C.; Federici,
   S.; Feinstein, F.; Ferenc, D.; Fillin-Martino, E.; Fink, D.; Finley,
   C.; Finley, J. P.; Firpo, R.; Florin, D.; Föhr, C.; Fokitis, E.;
   Font, Ll.; Fontaine, G.; Fontana, A.; Förster, A.; Fortson, L.;
   Fouque, N.; Fransson, C.; Fraser, G. W.; Fresnillo, L.; Fruck, C.;
   Fujita, Y.; Fukazawa, Y.; Funk, S.; Gäbele, W.; Gabici, S.; Gadola,
   A.; Galante, N.; Gallant, Y.; García, B.; García López, R. J.;
   Garrido, D.; Garrido, L.; Gascón, D.; Gasq, C.; Gaug, M.; Gaweda,
   J.; Geffroy, N.; Ghag, C.; Ghedina, A.; Ghigo, M.; Gianakaki, E.;
   Giarrusso, S.; Giavitto, G.; Giebels, B.; Giro, E.; Giubilato, P.;
   Glanzman, T.; Glicenstein, J. -F.; Gochna, M.; Golev, V.; Gómez
   Berisso, M.; González, A.; González, F.; Grañena, F.; Graciani,
   R.; Granot, J.; Gredig, R.; Green, A.; Greenshaw, T.; Grimm, O.;
   Grube, J.; Grudzińska, M.; Grygorczuk, J.; Guarino, V.; Guglielmi,
   L.; Guilloux, F.; Gunji, S.; Gyuk, G.; Hadasch, D.; Haefner, D.;
   Hagiwara, R.; Hahn, J.; Hallgren, A.; Hara, S.; Hardcastle, M. J.;
   Hassan, T.; Haubold, T.; Hauser, M.; Hayashida, M.; Heller, R.; Henri,
   G.; Hermann, G.; Herrero, A.; Hinton, J. A.; Hoffmann, D.; Hofmann,
   W.; Hofverberg, P.; Horns, D.; Hrupec, D.; Huan, H.; Huber, B.; Huet,
   J. -M.; Hughes, G.; Hultquist, K.; Humensky, T. B.; Huppert, J. -F.;
   Ibarra, A.; Illa, J. M.; Ingjald, J.; Inoue, Y.; Inoue, S.; Ioka, K.;
   Jablonski, C.; Jacholkowska, A.; Janiak, M.; Jean, P.; Jensen, H.;
   Jogler, T.; Jung, I.; Kaaret, P.; Kabuki, S.; Kakuwa, J.; Kalkuhl,
   C.; Kankanyan, R.; Kapala, M.; Karastergiou, A.; Karczewski, M.;
   Karkar, S.; Karlsson, N.; Kasperek, J.; Katagiri, H.; Katarzyński, K.;
   Kawanaka, N.; Kȩdziora, B.; Kendziorra, E.; Khélifi, B.; Kieda, D.;
   Kifune, T.; Kihm, T.; Klepser, S.; Kluźniak, W.; Knapp, J.; Knappy,
   A. R.; Kneiske, T.; Knödlseder, J.; Köck, F.; Kodani, K.; Kohri,
   K.; Kokkotas, K.; Komin, N.; Konopelko, A.; Kosack, K.; Kossakowski,
   R.; Kostka, P.; Kotuła, J.; Kowal, G.; Kozioł, J.; Krähenbühl,
   T.; Krause, J.; Krawczynski, H.; Krennrich, F.; Kretzschmann, A.;
   Kubo, H.; Kudryavtsev, V. A.; Kushida, J.; La Barbera, N.; La Parola,
   V.; La Rosa, G.; López, A.; Lamanna, G.; Laporte, P.; Lavalley, C.;
   Le Flour, T.; Le Padellec, A.; Lenain, J. -P.; Lessio, L.; Lieunard,
   B.; Lindfors, E.; Liolios, A.; Lohse, T.; Lombardi, S.; Lopatin,
   A.; Lorenz, E.; Lubiński, P.; Luz, O.; Lyard, E.; Maccarone, M. C.;
   Maccarone, T.; Maier, G.; Majumdar, P.; Maltezos, S.; Małkiewicz,
   P.; Mañá, C.; Manalaysay, A.; Maneva, G.; Mangano, A.; Manigot,
   P.; Marín, J.; Mariotti, M.; Markoff, S.; Martínez, G.; Martínez,
   M.; Mastichiadis, A.; Matsumoto, H.; Mattiazzo, S.; Mazin, D.; McComb,
   T. J. L.; McCubbin, N.; McHardy, I.; Medina, C.; Melkumyan, D.; Mendes,
   A.; Mertsch, P.; Meucci, M.; Michałowski, J.; Micolon, P.; Mineo,
   T.; Mirabal, N.; Mirabel, F.; Miranda, J. M.; Mirzoyan, R.; Mizuno,
   T.; Moal, B.; Moderski, R.; Molinari, E.; Monteiro, I.; Moralejo, A.;
   Morello, C.; Mori, K.; Motta, G.; Mottez, F.; Moulin, E.; Mukherjee,
   R.; Munar, P.; Muraishi, H.; Murase, K.; Murphy, A. Stj.; Nagataki,
   S.; Naito, T.; Nakamori, T.; Nakayama, K.; Naumann, C.; Naumann, D.;
   Nayman, P.; Nedbal, D.; Niedźwiecki, A.; Niemiec, J.; Nikolaidis,
   A.; Nishijima, K.; Nolan, S. J.; Nowak, N.; O'Brien, P. T.; Ochoa,
   I.; Ohira, Y.; Ohishi, M.; Ohka, H.; Okumura, A.; Olivetto, C.; Ong,
   R. A.; Orito, R.; Orr, M.; Osborne, J. P.; Ostrowski, M.; Otero, L.;
   Otte, A. N.; Ovcharov, E.; Oya, I.; Oziȩbło, A.; Paiano, S.; Pallota,
   J.; Panazol, J. L.; Paneque, D.; Panter, M.; Paoletti, R.; Papyan,
   G.; Paredes, J. M.; Pareschi, G.; Parsons, R. D.; Paz Arribas, M.;
   Pedaletti, G.; Pepato, A.; Persic, M.; Petrucci, P. O.; Peyaud,
   B.; Piechocki, W.; Pita, S.; Pivato, G.; Płatos, Ł.; Platzer,
   R.; Pogosyan, L.; Pohl, M.; Pojmański, G.; Ponz, J. D.; Potter,
   W.; Prandini, E.; Preece, R.; Prokoph, H.; Pühlhofer, G.; Punch,
   M.; Quel, E.; Quirrenbach, A.; Rajda, P.; Rando, R.; Rataj, M.;
   Raue, M.; Reimann, C.; Reimann, O.; Reimer, A.; Reimer, O.; Renaud,
   M.; Renner, S.; Reymond, J. -M.; Rhode, W.; Ribó, M.; Ribordy,
   M.; Rico, J.; Rieger, F.; Ringegni, P.; Ripken, J.; Ristori, P.;
   Rivoire, S.; Rob, L.; Rodriguez, S.; Roeser, U.; Romano, P.; Romero,
   G. E.; Rosier-Lees, S.; Rovero, A. C.; Roy, F.; Royer, S.; Rudak, B.;
   Rulten, C. B.; Ruppel, J.; Russo, F.; Ryde, F.; Sacco, B.; Saggion, A.;
   Sahakian, V.; Saito, K.; Saito, T.; Sakaki, N.; Salazar, E.; Salini,
   A.; Sánchez, F.; Sánchez Conde, M. Á.; Santangelo, A.; Santos,
   E. M.; Sanuy, A.; Sapozhnikov, L.; Sarkar, S.; Scalzotto, V.; Scapin,
   V.; Scarcioffolo, M.; Schanz, T.; Schlenstedt, S.; Schlickeiser, R.;
   Schmidt, T.; Schmoll, J.; Schroedter, M.; Schultz, C.; Schultze, J.;
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   J.; Selmane, S.; Seweryn, K.; Shayduk, M.; Shellard, R. C.; Shibata,
   T.; Sikora, M.; Silk, J.; Sillanpää, A.; Sitarek, J.; Skole, C.;
   Smith, N.; Sobczyńska, D.; Sofo Haro, M.; Sol, H.; Spanier, F.; Spiga,
   D.; Spyrou, S.; Stamatescu, V.; Stamerra, A.; Starling, R. L. C.;
   Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Steiner, S.; Stergioulas,
   N.; Sternberger, R.; Stinzing, F.; Stodulski, M.; Straumann, U.;
   Suárez, A.; Suchenek, M.; Sugawara, R.; Sulanke, K. H.; Sun, S.;
   Supanitsky, A. D.; Sutcliffe, P.; Szanecki, M.; Szepieniec, T.;
   Szostek, A.; Szymkowiak, A.; Tagliaferri, G.; Tajima, H.; Takahashi,
   H.; Takahashi, K.; Takalo, L.; Takami, H.; Talbot, R. G.; Tam, P. H.;
   Tanaka, M.; Tanimori, T.; Tavani, M.; Tavernet, J. -P.; Tchernin, C.;
   Tejedor, L. A.; Telezhinsky, I.; Temnikov, P.; Tenzer, C.; Terada,
   Y.; Terrier, R.; Teshima, M.; Testa, V.; Tibaldo, L.; Tibolla, O.;
   Tluczykont, M.; Todero Peixoto, C. J.; Tokanai, F.; Tokarz, M.; Toma,
   K.; Torres, D. F.; Tosti, G.; Totani, T.; Toussenel, F.; Vallania,
   P.; Vallejo, G.; van der Walt, J.; van Eldik, C.; Vandenbroucke, J.;
   Vankov, H.; Vasileiadis, G.; Vassiliev, V. V.; Vegas, I.; Venter, L.;
   Vercellone, S.; Veyssiere, C.; Vialle, J. P.; Videla, M.; Vincent,
   P.; Vink, J.; Vlahakis, N.; Vlahos, L.; Vogler, P.; Vollhardt, A.;
   Volpe, F.; von Gunten, H. P.; Vorobiov, S.; Wagner, S.; Wagner,
   R. M.; Wagner, B.; Wakely, S. P.; Walter, P.; Walter, R.; Warwick,
   R.; Wawer, P.; Wawrzaszek, R.; Webb, N.; Wegner, P.; Weinstein, A.;
   Weitzel, Q.; Welsing, R.; Wetteskind, H.; White, R.; Wierzcholska,
   A.; Wilkinson, M. I.; Williams, D. A.; Winde, M.; Wischnewski, R.;
   Wiśniewski, Ł.; Wolczko, A.; Wood, M.; Xiong, Q.; Yamamoto, T.;
   Yamaoka, K.; Yamazaki, R.; Yanagita, S.; Yoffo, B.; Yonetani, M.;
   Yoshida, A.; Yoshida, T.; Yoshikoshi, T.; Zabalza, V.; Zagdański,
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Bibcode: 2011ExA....32..193A
Altcode: 2011ExA...tmp..121A; 2010arXiv1008.3703C
  Ground-based gamma-ray astronomy has had a major breakthrough with
  the impressive results obtained using systems of imaging atmospheric
  Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge
  potential in astrophysics, particle physics and cosmology. CTA is
  an international initiative to build the next generation instrument,
  with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV
  range and the extension to energies well below 100 GeV and above 100
  TeV. CTA will consist of two arrays (one in the north, one in the south)
  for full sky coverage and will be operated as open observatory. The
  design of CTA is based on currently available technology. This document
  reports on the status and presents the major design concepts of CTA.

Title: Gravitational redshifts in main-sequence and giant stars
Authors: Pasquini, L.; Melo, C.; Chavero, C.; Dravins, D.; Ludwig,
   H. -G.; Bonifacio, P.; de La Reza, R.
Bibcode: 2011A&A...526A.127P
Altcode: 2010arXiv1011.4635P
  Context. Precise analyses of stellar radial velocities is able to
  reveal intrinsic causes of the wavelength shifts of spectral lines
  (other than Doppler shifts due to radial motion), such as gravitational
  redshifts and convective blueshifts. <BR /> Aims: Gravitational
  redshifts in solar-type main-sequence stars are expected to be some
  500 m s<SUP>-1</SUP> greater than those in giants. We search for this
  difference in redshifts among groups of open-cluster stars that share
  the same average space motion and thus have the same average Doppler
  shift. <BR /> Methods: We observed 144 main-sequence stars and cool
  giants in the M 67 open cluster using the ESO FEROS spectrograph and
  obtained radial velocities by means of cross-correlation with a spectral
  template. Binaries and doubtful members were not analyzed, and average
  spectra were created for different classes of stars. <BR /> Results:
  The M 67 dwarf and giant radial-velocity distributions are each well
  represented by Gaussian functions, which share the same apparent average
  radial velocity to within ≃100 m s<SUP>-1</SUP>. In addition, dwarfs
  in M 67 appear to be dynamically hotter (σ = 0.90 km s<SUP>-1</SUP>)
  than giants (σ = 0.68 km s<SUP>-1</SUP>). <BR /> Conclusions: We fail
  to detect any difference in the gravitational redshifts of giants and
  MS stars. This is probably because of the differential wavelength
  shifts produced by the different hydrodynamics of dwarf and giant
  atmospheres. Radial-velocity differences measured between unblended
  lines in averaged spectra vary with line-strength: stronger lines
  are more blueshifted in dwarfs than in giants, apparently removing
  any effect of the gravitational redshift. Synthetic high-resolution
  spectra are computed from three dimensional (3D) hydrodynamic model
  atmospheres for both giants and dwarfs, and synthetic wavelength
  shifts obtained. In agreement with observations, 3D models predict
  substantially smaller wavelength-shift differences than expected from
  gravitational redshifts only. The procedures developed could be used
  to test 3D models for different classes of stars, but will ultimately
  require high-fidelity spectra for measurements of wavelength shifts in
  individual spectral lines. <P />Based on observations collected at ESO,
  La Silla, Chile, during the agreement between the Observatorio Nacional
  at Rio de Janeiro and ESO.Table 1 is available in electronic form at <A
  href="http://www.aanda.org">http://www.aanda.org</A> and also at the
  CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
  href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/526/A127">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/526/A127</A>

Title: VizieR Online Data Catalog: Velocities of M67 main-sequence
    and giant stars (Pasquini+, 2011)
Authors: Pasquini, L.; Melo, C.; Chavero, C.; Dravins, D.; Ludwig,
   H. -G.; Bonifacio, P.; de La, Reza R.
Bibcode: 2011yCat..35260127P
Altcode: 2011yCat..35269127P
  We observed 144 main-sequence stars and cool giants in the M67 open
  cluster using the ESO FEROS spectrograph and obtained radial velocities
  by means of cross-correlation with a spectral template. Binaries and
  doubtful members were not analyzed, and average spectra were created
  for different classes of stars. <P />(1 data file).

Title: Stellar intensity interferometry: experimental steps toward
    long-baseline observations
Authors: LeBohec, Stephan; Adams, Ben; Bond, Isobel; Bradbury, Stella;
   Dravins, Dainis; Jensen, Hannes; Kieda, David B.; Kress, Derrick;
   Munford, Edward; Nuñez, Paul D.; Price, Ryan; Ribak, Erez; Rose,
   Joachim; Simpson, Harold; Smith, Jeremy
Bibcode: 2010SPIE.7734E..1DL
Altcode: 2010arXiv1009.5585L; 2010SPIE.7734E..40L
  Experiments are in progress to prepare for intensity interferometry with
  arrays of air Cherenkov telescopes. At the Bonneville Seabase site, near
  Salt Lake City, a testbed observatory has been set up with two 3-m air
  Cherenkov telescopes on a 23-m baseline. Cameras are being constructed,
  with control electronics for either off- or online analysis of the
  data. At the Lund Observatory (Sweden) and in Technion (Israel) and
  at the University of Utah (USA), laboratory intensity interferometers
  simulating stellar observations have been set up and experiments are in
  progress, using various analog and digital correlators, reaching 1.4 ns
  time resolution, to analyze signals from pairs of laboratory telescopes.

Title: Stellar intensity interferometry: astrophysical targets for
    sub-milliarcsecond imaging
Authors: Dravins, Dainis; Jensen, Hannes; LeBohec, Stephan; Nuñez,
   Paul D.
Bibcode: 2010SPIE.7734E..0AD
Altcode: 2010arXiv1009.5815D; 2010SPIE.7734E...9D
  Intensity interferometry permits very long optical baselines and
  the observation of sub-milliarcsecond structures. Using planned
  kilometric arrays of air Cherenkov telescopes at short wavelengths,
  intensity interferometry may increase the spatial resolution achieved
  in optical astronomy by an order of magnitude, inviting detailed
  studies of the shapes of rapidly rotating hot stars with structures
  in their circumstellar disks and winds, or mapping out patterns
  of nonradial pulsations across stellar surfaces. Signal-to-noise
  in intensity interferometry favors high-temperature sources and
  emission-line structures, and is independent of the optical passband,
  be it a single spectral line or the broad spectral continuum. Prime
  candidate sources have been identified among classes of bright and
  hot stars. Observations are simulated for telescope configurations
  envisioned for large Cherenkov facilities, synthesizing numerous
  optical baselines in software, confirming that resolutions of tens of
  microarcseconds are feasible for numerous astrophysical targets.

Title: Stellar intensity interferometry: optimizing air Cherenkov
    telescope array layouts
Authors: Jensen, Hannes; Dravins, Dainis; LeBohec, Stephan; Nuñez,
   Paul D.
Bibcode: 2010SPIE.7734E..1TJ
Altcode: 2010SPIE.7734E..54J; 2010arXiv1009.5828J
  Kilometric-scale optical imagers seem feasible to realize by intensity
  interferometry, using telescopes primarily erected for measuring
  Cherenkov light induced by gamma rays. Planned arrays envision 50-100
  telescopes, distributed over some 1-4 km<SUP>2</SUP>. Although
  array layouts and telescope sizes will primarily be chosen for
  gamma-ray observations, also their interferometric performance may be
  optimized. Observations of stellar objects were numerically simulated
  for different array geometries, yielding signal-to-noise ratios for
  different Fourier components of the source images in the interferometric
  (u, v)-plane. Simulations were made for layouts actually proposed for
  future Cherenkov telescope arrays, and for subsets with only a fraction
  of the telescopes. All large arrays provide dense sampling of the (u,
  v)-plane due to the sheer number of telescopes, irrespective of their
  geographic orientation or stellar coordinates. However, for improved
  coverage of the (u, v)-plane and a wider variety of baselines (enabling
  better image reconstruction), an exact east-west grid should be avoided
  for the numerous smaller telescopes, and repetitive geometric patterns
  avoided for the few large ones. Sparse arrays become severely limited
  by a lack of short baselines, and to cover astrophysically relevant
  dimensions between 0.1-3 milliarcseconds in visible wavelengths,
  baselines between pairs of telescopes should cover the whole interval
  30-2000 m.

Title: Stellar intensity interferometry: imaging capabilities of
    air Cherenkov telescope arrays
Authors: Nuñez, Paul D.; LeBohec, Stephan; Kieda, David; Holmes,
   Richard; Jensen, Hannes; Dravins, Dainis
Bibcode: 2010SPIE.7734E..1CN
Altcode: 2010arXiv1009.5599N; 2010SPIE.7734E..39N
  Sub milli-arcsecond imaging in the visible band will provide a new
  perspective in stellar astrophysics. Even though stellar intensity
  interferometry was abandoned more than 40 years ago, it is capable of
  imaging and thus accomplishing more than the measurement of stellar
  diameters as was previously thought. Various phase retrieval techniques
  can be used to reconstruct actual images provided a sufficient coverage
  of the interferometric plane is available. Planned large arrays of Air
  Cherenkov telescopes will provide thousands of simultaneously available
  baselines ranging from a few tens of meters to over a kilometer, thus
  making imaging possible with unprecedented angular resolution. Here we
  investigate the imaging capabilities of arrays such as CTA or AGIS used
  as Stellar Intensity Interferometry receivers. The study makes use of
  simulated data as could realistically be obtained from these arrays. A
  Cauchy-Riemann based phase recovery allows the reconstruction of images
  which can be compared to the pristine image for which the data were
  simulated. This is first done for uniform disk stars with different
  radii and corresponding to various exposure times, and we find that
  the uncertainty in reconstructing radii is a few percent after a few
  hours of exposure time. Finally, more complex images are considered,
  showing that imaging at the sub-milli-arc-second scale is possible.

Title: High-fidelity spectroscopy at the highest resolutions
Authors: Dravins, D.
Bibcode: 2010AN....331..535D
Altcode: 2010arXiv1002.1190D
  High-fidelity spectroscopy presents challenges for both observations
  and in designing instruments. High-resolution and high-accuracy
  spectra are required for verifying hydrodynamic stellar atmospheres
  and for resolving intergalactic absorption-line structures in
  quasars. Even with great photon fluxes from large telescopes with
  matching spectrometers, precise measurements of line profiles and
  wavelength positions encounter various physical, observational, and
  instrumental limits. The analysis may be limited by astrophysical
  and telluric blends, lack of suitable lines, imprecise laboratory
  wavelengths, or instrumental imperfections. To some extent, such limits
  can be pushed by forming averages over many similar spectral lines,
  thus averaging away small random blends and wavelength errors. In
  situations where theoretical predictions of lineshapes and shifts can
  be accurately made (e.g., hydrodynamic models of solar-type stars),
  the consistency between noisy observations and theoretical predictions
  may be verified; however this is not feasible for, e.g., the complex
  of intergalactic metal lines in spectra of distant quasars, where
  the primary data must come from observations. To more fully resolve
  lineshapes and interpret wavelength shifts in stars and quasars alike,
  spectral resolutions on order R=300 000 or more are required; a level
  that is becoming (but is not yet) available. A grand challenge remains
  to design efficient spectrometers with resolutions approaching R=1
  000 000 for the forthcoming generation of extremely large telescopes.

Title: Division Iv: Stars
Authors: Spite, Monique; Corbally, Christopher; Dravins, Dainis; Allen,
   Christine; d'Antona, Francesca; Giridhar, Sunetra; Landstreet, John;
   Parthasarathy, Mudumba
Bibcode: 2010IAUTB..27..188S
Altcode:
  During the General Assembly in Rio de Janeiro the Division IV meeting,
  and the meetings of the participating working groups and commissions,
  were held on thursday 6th (session 1 and 2) and friday 7th (sessions 1,
  2, 3, 4).

Title: Towards a Square-Kilometer Optical Telescope: The Potential
    of Intensity Interferometry
Authors: Dravins, D.
Bibcode: 2010RMxAC..38...17D
Altcode:
  Kilometric-scale optical baselines are required for imaging features
  across stellar disks. Ground-based intensity interferometry is
  insensitive to both atmospheric turbulence and to imperfections
  in telescope optics, permitting long-baseline observations even at
  short optical wavelengths. Its required large flux collectors are
  becoming available as arrays of atmospheric Cherenkov telescopes
  set up for studying energetic gamma rays. High-speed detectors and
  digital signal handling enable very many baselines to be synthesized
  in software between numerous pairs of telescopes in a digital revival
  of a technique once pioneered by Hanbury Brown &amp; Twiss.

Title: High Time Resolution Astrophysics in the Extremely Large
Telescope Era : White Paper
Authors: Shearer, A.; Kanbach, G.; Slowikowska, A.; Barbieri, C.;
   Marsh, T.; Dhillon, V.; Mignani, R.; Dravins, D.; Gouiffes, c.;
   MacKay, C.; Bonanno, G.; Collins, S.
Bibcode: 2010htra.confE..54S
Altcode: 2010PoS...108E..54S; 2010arXiv1008.0605S
  High Time Resolution Astrophysics (HTRA) concerns itself with
  observations on short scales normally defined as being lower than
  the conventional read-out time of a CCD. As such it is concerned with
  condensed objects such as neutron stars, black holes and white dwarfs,
  surfaces with extreme magnetic reconnection phenomena, as well as
  with planetary scale objects through transits and occultations. HTRA
  is the only way to make a major step forward in our understanding of
  several important astrophysical and physical processes; these include
  the extreme gravity conditions around neutron stars and stable orbits
  around stellar mass black holes. Transits, involving fast timing,
  can give vital information on the size of, and satellites around
  exoplanets. In the realm of fundamental physics very interesting
  applications lie in the regime of ultra-high time resolution, where
  quantum-physical phenomena, currently studied in laboratory physics,
  may be explored. HTRA science covers the full gamut of observational
  optical/IR astronomy from asteroids to {\gamma}-rays bursts,
  contributing to four out of six of AstroNet's fundamental challenges
  described in their Science Vision for European Astronomy. Giving
  the European-Extremely Large Telescope (E-ELT) an HTRA capability is
  therefore importance. We suggest that there are three possibilities
  for HTRA and E-ELT. These are, firstly giving the E-ELT first light
  engineering camera an HTRA science capability. Secondly, to include
  a small HTRA instrument within another instrument. Finally, to have
  separate fibre feeds to a dedicated HTRA instrument. In this case a
  small number of fibres could be positioned and would provide a flexible
  and low cost means to have an HTRA capability. By the time of E-ELT
  first light, there should be a number of significant developments in
  fast detector arrays, in particular in the infra-red (IR) region.

Title: High-Fidelity Spectroscopy at the Highest Resolution
Authors: Dravins, Dainis
Bibcode: 2010RvMA...22..191D
Altcode:
  No abstract at ADS

Title: Towards the Intensity Interferometry Stellar Imaging System
Authors: Daniel, M.; de Wit, W. J.; Dravins, D.; Kieda, D.; LeBohec,
   S.; Nunez, P.; Ribak, E.
Bibcode: 2009arXiv0906.3276D
Altcode:
  The imminent availability of large arrays of large light collectors
  deployed to exploit atmospheric Cherenkov radiation for gamma-ray
  astronomy at more than 100GeV, motivates the growing interest in
  application of intensity interferometry in astronomy. Indeed, planned
  arrays numbering up to one hundred telescopes will offer close to 5,000
  baselines, ranging from less than 50m to more than 1000m. Recent and
  continuing signal processing technology developments reinforce this
  interest. Revisiting Stellar Intensity Interferometry for imaging
  is well motivated scientifically. It will fill the short wavelength
  (B/V bands) and high angular resolution (&lt; 0.1mas) gap left open
  by amplitude interferometers. It would also constitute a first and
  important step toward exploiting quantum optics for astronomical
  observations, thus leading the way for future observatories. In this
  paper we outline science cases, technical approaches and schedule
  for an intensity interferometer to be constructed and operated in the
  visible using gamma-ray astronomy Air Cherenkov Telescopes as receivers.

Title: New Astrophysical Opportunities Exploiting Spatio-Temporal
    Optical Correlations
Authors: Barbieri, C.; Daniel, M. K.; de Wit, W. J.; Dravins, D.;
   Jensen, H.; Kervella, P.; Le Bohec, S.; Malbet, F.; Nunex, P.; Ralston,
   J. P.; Ribak, E. N.
Bibcode: 2009astro2010S..61B
Altcode: 2009arXiv0903.0062B; 2009astro2010S..61D
  The space-time correlations of streams of photons can provide
  fundamentally new channels of information about the Universe. Today's
  astronomical observations essentially measure certain amplitude
  coherence functions produced by a source. The spatial correlations
  of wave fields has traditionally been exploited in Michelson-style
  amplitude interferometry. However the technology of the past was
  largely incapable of fine timing resolution and recording multiple
  beams. When time and space correlations are combined it is possible
  to achieve spectacular measurements that are impossible by any other
  means. Stellar intensity interferometry is ripe for development
  and is one of the few unexploited mechanisms to obtain potentially
  revolutionary new information in astronomy. As we discuss below, the
  modern use of stellar intensity interferometry can yield unprecedented
  measures of stellar diameters, binary stars, distance measures including
  Cepheids, rapidly rotating stars, pulsating stars, and short-time
  scale fluctuations that have never been measured before.

Title: Highest-resolution spectroscopy at the largest telescopes?
Authors: Dravins, Dainis
Bibcode: 2009MmSAI..80..614D
Altcode:
  3-D models of stellar atmospheres predict spectral-line shapes
  with asymmetries and wavelength shifts, but the confrontation with
  observations is limited by blends, lack of suitable lines, imprecise
  laboratory wavelengths, and instrumental imperfections. Limits
  can be pushed by averaging many similar lines, thus averaging small
  random blends and wavelength errors. In non-solar cases, any detailed
  verification of 3-D hydrodynamics requires spectra of resolutions R =
  lambda /Delta lambda ≈ 300,000, soon to become available. An issue
  is the optical interface of high-resolution spectrometers to [very]
  large telescopes with their [very] large image scales, possibly
  requiring adaptive optics. The next observational frontier may be
  spectroscopy across spatially resolved stellar disks, utilizing optical
  interferometers and extremely large telescopes.

Title: Division IV: Stars
Authors: Spite, Monique; Corbally, Christopher J.; Dravins, Dainis;
   Allen, Christine; d'Antona, Francesca; Giridhar, Sunetra; Landstreet,
   John D.; Parthasarathy, Mudumba
Bibcode: 2009IAUTA..27..193S
Altcode:
  IAU Division IV organizes astronomers studying the characteristics,
  interior and atmospheric structure, and evolution of stars of all
  masses, ages, and chemical compositions.

Title: ``Ultimate'' information content in solar and stellar
    spectra. Photospheric line asymmetries and wavelength shifts
Authors: Dravins, Dainis
Bibcode: 2008A&A...492..199D
Altcode: 2008arXiv0810.2533D
  Context: Spectral-line asymmetries (displayed as bisectors) and
  wavelength shifts are signatures of the hydrodynamics in solar and
  stellar atmospheres. Theory may precisely predict idealized lines,
  but accuracies in real observed spectra are limited by blends, few
  suitable lines, imprecise laboratory wavelengths, and instrumental
  imperfections. <BR />Aims: We extract bisectors and shifts until
  the “ultimate” accuracy limits in highest-quality solar and
  stellar spectra, so as to understand the various limits set by
  (i) stellar physics (number of relevant spectral lines, effects of
  blends, rotational line broadening); by (ii) observational techniques
  (spectral resolution, photometric noise); and by (iii) limitations
  in laboratory data. <BR />Methods: Several spectral atlases of the
  Sun and bright solar-type stars were examined for those thousands of
  “unblended” lines with the most accurate laboratory wavelengths,
  yielding bisectors and shifts as averages over groups of similar
  lines. Representative data were obtained as averages over groups
  of similar lines, thus minimizing the effects of photometric noise
  and of random blends. <BR />Results: For the solar-disk center and
  integrated sunlight, the bisector shapes and shifts were extracted
  for previously little-studied species (Fe II, Ti I, Ti II, Cr II,
  Ca I, C I), using recently determined and very accurate laboratory
  wavelengths. In Procyon and other F-type stars, a sharp blueward bend
  in the bisector near the spectral continuum is confirmed, revealing
  line saturation and damping wings in upward-moving photospheric
  granules. Accuracy limits are discussed: “astrophysical” noise due
  to few measurable lines, finite instrumental resolution, superposed
  telluric absorption, inaccurate laboratory wavelengths, and calibration
  noise in spectrometers, together limiting absolute lineshift studies
  to ≈50-100 m s<SUP>-1</SUP>. <BR />Conclusions: Spectroscopy with
  resolutions λ/Δλ ≈ 300 000 and accurate wavelength calibration
  will enable bisector studies for many stars. Circumventing remaining
  limits of astrophysical noise in line-blends and rotationally smeared
  profiles may ultimately require spectroscopy across spatially resolved
  stellar disks, utilizing optical interferometers and extremely large
  telescopes of the future. <P />Tables are only available in electronic
  form at http://www.aanda.org

Title: Toward a revival of stellar intensity interferometry
Authors: LeBohec, Stephan; Barbieri, Cesare; de Wit, Willem-Jan;
   Dravins, Dainis; Feautrier, Philippe; Foellmi, Cédric; Glindemann,
   Andreas; Hall, Jeter; Holder, Jamie; Holmes, Richard; Kervella,
   Pierre; Kieda, David; Le Coarer, Etienne; Lipson, Stephan; Malbet,
   Fabien; Morel, Sébastien; Nuñez, Paul; Ofir, Aviv; Ribak, Erez;
   Saha, Swapan; Schoeller, Markus; Zhilyaev, Boriz; Zinnecker, Hans
Bibcode: 2008SPIE.7013E..2EL
Altcode: 2008SPIE.7013E..72L
  Building on technological developments over the last 35 years,
  intensity interferometry now appears a feasible option by which to
  achieve diffraction-limited imaging over a square-kilometer synthetic
  aperture. Upcoming Atmospheric Cherenkov Telescope projects will
  consist of up to 100 telescopes, each with ~100m<SUP>2</SUP> of light
  gathering area, and distributed over ~1km<SUP>2</SUP>. These large
  facilities will offer thousands of baselines from 50m to more than 1km
  and an unprecedented (u,v) plane coverage. The revival of interest
  in Intensity Interferometry has recently led to the formation of a
  IAU working group. Here we report on various ongoing efforts towards
  implementing modern Stellar Intensity Interferometry.

Title: Toward a diffraction-limited square-kilometer optical
telescope: digital revival of intensity interferometry
Authors: Dravins, Dainis; LeBohec, Stephan
Bibcode: 2008SPIE.6986E..09D
Altcode: 2008SPIE.6986E...9D
  Much of the progress in astronomy follows imaging with improved
  resolution. In observing stars, current capabilities are only
  marginal in beginning to image the disks of a few, although many
  stars will appear as surface objects for baselines of hundreds
  of meters. Since atmospheric turbulence makes ground-based phase
  interferometry challenging for such long baselines, kilometric
  space telescope clusters have been proposed for imaging stellar
  surface details. The realization of such projects remains uncertain,
  but comparable imaging could be realized by ground-based intensity
  interferometry. While insensitive to atmospheric turbulence and
  imperfections in telescope optics, the method requires large flux
  collectors, such as being set up as arrays of atmospheric Cherenkov
  telescopes for studying energetic gamma rays. High-speed detectors and
  digital signal handling enable very many baselines to be synthesized
  between pairs of telescopes, while stars may be tracked across the sky
  by electronic time delays. First observations with digitally combined
  optical instruments have now been made with pairs of 12-meter telescopes
  of the VERITAS array in Arizona. Observing at short wavelengths adds no
  problems, and similar techniques on an extremely large telescope could
  achieve diffraction-limited imaging down to the atmospheric cutoff,
  achieving a spatial resolution significantly superior by that feasible
  by adaptive optics operating in the red or near-infrared.

Title: Photon Correlation Spectroscopy for Observing Natural Lasers
Authors: Dravins, Dainis; Germanà, Claudio
Bibcode: 2008AIPC..984..216D
Altcode: 2007arXiv0710.1756D
  Natural laser emission may be produced whenever suitable atomic
  energy levels become overpopulated. Strong evidence for laser emission
  exists in astronomical sources such as Eta Carinae, and other luminous
  stars. However, the evidence is indirect in that the laser lines have
  not yet been spectrally resolved. The lines are theoretically estimated
  to be extremely narrow, requiring spectral resolutions very much higher
  (R~10<SUP>8</SUP>) than possible with ordinary spectroscopy. Such can be
  attained with photon-correlation spectroscopy on nanosecond timescales,
  measuring the autocorrelation function of photon arrival times to
  obtain the coherence time of light, and thus the spectral linewidth. A
  particular advantage is the insensitivity to spectral, spatial, and
  temporal shifts of emission-line components due to local velocities
  and probable variability of `hot-spots' in the source. A laboratory
  experiment has been set up, simulating telescopic observations of
  cosmic laser emission. Numerically simulated observations estimate
  how laser emission components within realistic spectral and spatial
  passbands for various candidate sources carry over to observable
  statistical functions.

Title: Intrinsic Lineshifts in Astronomical Spectra
Authors: Dravins, Dainis
Bibcode: 2008psa..conf..139D
Altcode:
  Spectral-line displacements away from the wavelengths naively expected
  from the Doppler shift due to radial motion may originate as convective
  shifts (correlated velocity and brightness patterns), as gravitational
  redshifts, or be induced by wave motions. Convective shifts are
  important tools for testing 3-dimensional stellar hydrodynamics;
  analogous shifts may be expected even in intergalactic absorption lines
  (convection driven by AGNs in clusters of galaxies).

Title: Photonic Astronomy and Quantum Optics
Authors: Dravins, Dainis
Bibcode: 2008ASSL..351...95D
Altcode: 2007astro.ph..1220D
  Quantum optics potentially offers an information channel from the
  Universe beyond the established ones of imaging and spectroscopy. All
  existing cameras and all spectrometers measure aspects of the
  first-order spatial and/or temporal coherence of light. However,
  light has additional degrees of freedom, manifest in the statistics
  of photon arrival times, or in the amount of photon orbital angular
  momentum. Such quantum-optical measures may carry information on
  how the light was created at the source, and whether it reached
  the observer directly or via some intermediate process. Astronomical
  quantum optics may help to clarify emission processes in natural laser
  sources and in the environments of compact objects, while high-speed
  photon-counting with digital signal handling enables multi-element
  and long-baseline versions of the intensity interferometer. Time
  resolutions of nanoseconds are required, as are large photon fluxes,
  making photonic astronomy very timely in an era of large telescopes.

Title: Division Iv: Stars
Authors: Dravins, Dainis; Spite, Monique; Barbuy, Beatriz; Corbally,
   Christopher; Dziembowski, Wojciech; Hartkopf, William I.; Sneden,
   Christopher
Bibcode: 2007IAUTB..26..145D
Altcode:
  Division IV organizes astronomers studying the characterization,
  interior and atmospheric structure of stars of all masses, ages and
  chemical compositions.

Title: Commission 36: Theory of Stellar Atmospheres
Authors: Spite, Monique; Landstreet, John D.; Asplund, Martin; Ayres,
   Thomas R.; Balachandran, Suchitra C.; Dravins, Dainis; Hauschildt,
   Peter H.; Kiselman, Dan; Nagendra, K. N.; Sneden, Christopher;
   Tautvaišiené, Grazina; Werner, Klaus
Bibcode: 2007IAUTB..26..160S
Altcode:
  The business meeting of Commission 36 was held during the General
  Assembly in Prague on 16 August. It was attended by about 15
  members. The issues presented included a review of the work made
  by members of Commission 36, and the election of the new Organising
  Committee. We note that a comprehensive report on the activities of
  the commission during the last triennium has been published in Reports
  on Astronomy, Transactions IAU Volume XXVIA. The scientific activity
  of the members of the commission has been very intense, and has led
  to the publication of a large number of papers.

Title: Commission 30: Radial Velocities
Authors: Nordström, Birgitta; Udry, Stéphane; Tokovinin, Andrei A.;
   Dravins, Dainis; Fekel, Francis C.; Glushkova, Elena V.; Levato, Hugo;
   Pourbaix, Dimitri; Smith, Myron A.; Szabados, Laszlo; Torres, Guillermo
Bibcode: 2007IAUTB..26..197N
Altcode:
  The president welcomed all the participants of the Business Meeting
  and remarked that several of the major ongoing and planned Radial
  Velocity projects were well represented.

Title: Wolfe Creek Crater in Western Australia
Authors: Dravins, Dainis
Bibcode: 2007S&T...114d.102D
Altcode:
  No abstract at ADS

Title: Searching for Optical Lasers in Emission-Line Stars
Authors: Dravins, Dainis; Germano, Claudio
Bibcode: 2007jena.confE..26D
Altcode:
  Natural laser emission may be produced whenever radiative mechanisms
  overpopulate suitable atomic energy levels. Well-studied cases
  are optical emission lines from gas ejecta around the extremely
  luminous star Eta Carinae. Theoretically expected linewidths are
  very narrow, requiring spectral resolution around 100 million,
  far beyond classical spectroscopy. Such resolutions are feasible
  with nanosecond-resolution photon-correlation spectroscopy, a
  quantum-optical method of analyzing the autocorrelation function of
  photon arrival times. Observations with large telescopes are simulated
  both numerically, and in a laboratory experiment measuring narrow
  emission lines with photon-counting avalanche photodiodes. Further
  discussion: http://www.astro.lu.se/~dainis/

Title: Very fast photon counting photometers for astronomical
applications: from QuantEYE to AquEYE
Authors: Naletto, Giampiero; Barbieri, Cesare; Occhipinti, Tommaso;
   Tamburini, Fabrizio; Billotta, Sergio; Cocuzza, Silvio; Dravins, Dainis
Bibcode: 2007SPIE.6583E..0BN
Altcode: 2007SPIE.6583E...9N
  In the great majority of the cases, present astronomical observations
  are realized analyzing only first order spatial or temporal
  coherence properties of the collected photon stream. However, a lot
  of information is "hidden" in the second and higher order coherence
  terms, as details about a possible stimulated emission mechanism
  or about photon scattering along the travel from the emitter to the
  telescope. The Extremely Large Telescopes of the future could provide
  the high photon flux needed to extract this information. To this aim
  we have recently studied a possible focal plane instrument, named
  QuantEYE, for the 100 m OverWhelmingly Large Telescope of the European
  Southern Observatory. This instrument is the fastest photon counting
  photometer ever conceived, with an array of 100 parallel channels
  operating simultaneously, to push the time tagging capabilities toward
  the pico-second region. To acquire some experience with this novel
  type of instrumentation, we are now in the process of realizing a
  small instrument prototype (AquEYE) for the Asiago 182 cm telescope,
  for then building a larger instrument for one of the existing 8-10
  m class telescopes. We hope that the results we will obtain by these
  instruments will open a new frontier in the astronomical observations.

Title: Commission 36: Theory of Stellar Atmospheres
Authors: Spite, Monique; Landstreet, John; Asplund, M.; Ayres, T.;
   Balachandran, S.; Dravins, D.; Hauschildt, P.; Kiselman, D.; Nagendra,
   K. N.; Sneden, C.; Tautvaišiené, G.; Werner, K.
Bibcode: 2007IAUTA..26..215S
Altcode:
  Commission 36 covers all the physics of stellar atmospheres. The
  scientific activity in this large field has been very intense during
  the last triennium and led to the publication of a large number of
  papers which makes an exhaustive report practically not feasible. As
  a consequence we decided to keep the format of the preceding report:
  first a list of areas of current research, then web links for obtaining
  further information.

Title: Commission 12: Solar Radiation &amp; Structure
Authors: Bogdan, Thomas. J.; Martínez Pillet, Valentin; Asplund,
   M.; Christensen-Dalsgaard, J.; Cauzzi, G.; Cram, L. E.; Dravins, D.;
   Gan, W.; Henzl, P.; Kosovichev, A.; Mariska, J. T.; Rovira, M. G.;
   Venkatakrishnan, P.
Bibcode: 2007IAUTA..26...89B
Altcode:
  Commission 12 covers research on the internal structure and dynamics
  of the Sun, the "quiet" solar atmosphere, solar radiation and its
  variability, and the nature of relatively stable magnetic structures
  like sunspots, faculae and the magnetic network. There is considerable
  productive overlap with the other Commissions of Division II as
  investigations move progressively toward the fertile intellectual
  boundaries between traditional research disciplines. In large part,
  the solar magnetic field provides the linkage that connects these
  diverse themes. The same magnetic field that produces the more subtle
  variations of solar structure and radiative output over the 11 yr
  activity cycle is also implicated in rapid and often violent phenomena
  such as flares, coronal mass ejections, prominence eruptions, and
  episodes of sporadic magnetic reconnection.The last three years have
  again brought significant progress in nearly all the research endeavors
  touched upon by the interests of Commission 12. The underlying causes
  for this success remain the same: sustained advances in computing
  capabilities coupled with diverse observations with increasing levels
  of spatial, temporal and spectral resolution. It is all but impossible
  to deal with these many advances here in anything except a cursory and
  selective fashion. Thankfully, the Living Reviews in Solar Physics; has
  published several extensive reviews over the last two years that deal
  explicitly with issues relevant to the purview of Commission 12. The
  reader who is eager for a deeper and more complete understanding of
  some of these advances is directed to http://www.livingreviews.org
  for access to these articles.

Title: Division IV: Stars
Authors: Dravins, Dainis; Barbuy, Beatriz; Corbally, Christopher;
   Dziembowski, Wojciech; Hartkopf, William; Sneden, Christopher;
   Spite, Monique
Bibcode: 2007IAUTA..26..191D
Altcode:
  The IAU Division IV (`Stars') organizes astronomers studying the
  characteristics, interior and atmospheric structure, and evolution of
  stars of all masses, ages, and chemical compositions.

Title: COMMISSION 30: Radial Velocities*
Authors: Nordström, Birgitta; Udry, Stephane; Dravins, D.; Fekel,
   F.; Glushkova, E.; Levato, H.; Pourbaix, D.; Smith, M. A.; Szabados,
   L.; Torres, G.
Bibcode: 2007IAUTA..26E...1N
Altcode:
  This report from Commission 30 covers the salient areas in which
  major progress has been made in the triennium covered by the
  present volume. The principal scientific areas are: The Milky Way,
  star clusters, spectroscopic binaries, extrasolar planets, pulsating
  stars and stellar oscillations. Following these, an account is given
  of the progress in techniques and methodology for radial velocity
  determinations. Finally, a summary is given of the progress made
  by the working groups of the Commission, followed by a list of key
  papers in the triennium. A more extensive report also covering
  extragalactic work, which due to unforeseen circumstances could
  not be included here, can be found at the web page of Commission 30
  (http://www.iau.org/IAU/Organization/divcom/).

Title: Astronomical applications of quantum optics for extremely
    large telescopes
Authors: Barbieri, C.; Dravins, D.; Occhipinti, T.; Tamburini, F.;
   Naletto, G.; da Deppo, V.; Fornasier, S.; D'Onofrio, M.; Fosbury,
   R. A. E.; Nilsson, R.; Uthas, H.
Bibcode: 2007JMOp...54..191B
Altcode:
  No abstract at ADS

Title: QuantEYE: a quantum optics instrument for extremely large
    telescopes
Authors: Naletto, Giampiero; Barbieri, Cesare; Dravins, Dainis;
   Occhipinti, Tommaso; Tamburini, Fabrizio; Da Deppo, Vania; Fornasier,
   Sonia; D'Onofrio, Mauro; Fosbury, Robert A. E.; Nilsson, Ricky; Uthas,
   Helena; Zampieri, Luca
Bibcode: 2006SPIE.6269E..1WN
Altcode: 2006SPIE.6269E..62N
  We have carried out a conceptual study for an instrument (QuantEYE)
  capable to detect and measure photon-stream statistics, e.g. power
  spectra or autocorrelation functions. Such functions increase with
  the square of the detected signal, implying an enormously increased
  sensitivity at the future Extremely Large Telescopes, such as
  the OverWhelmingly Large (OWL) telescope of the European Southern
  Observatory (ESO). Furthermore, QuantEYE will have the capability
  of exploring astrophysical variability on microsecond and nanosecond
  scales, down to the quantum-optical limit. Expected observable phenomena
  include instabilities of photon-gas bubbles in accretion flows, p-mode
  oscillations in neutron stars, and quantum-optical photon bunching in
  time. This paper describes QuantEYE, an instrument aimed to realize
  the just described science, proposed for installation at the ESO OWL
  telescope focal plane. The adopted optical solution is relatively
  simple and possible with actual technologies, the main constraint
  essentially being the present limited availability of very fast photon
  counting detector arrays. Also some possible alternative designs are
  described, assuming a future technology development of fast photon
  counting detector arrays.

Title: Astronomical quantum optics with Extremely Large Telescopes
Authors: Dravins, D.; Barbieri, C.; Fosbury, R. A. E.; Naletto, G.;
   Nilsson, R.; Occhipinti, T.; Tamburini, F.; Uthas, H.; Zampieri, L.
Bibcode: 2006IAUS..232..502D
Altcode:
  Modern optics focuses on photonics and quantum optics, studying
  individual photons and statistics of photon streams. Those can be
  complex and carry information beyond that recorded by imaging,
  spectroscopy, polarimetry or interferometry. Since [almost] all
  astronomy is based upon the interpretation of subtleties in the light
  from astronomical sources, quantum optics has the potential of becoming
  another information channel from the Universe. The observability
  of quantum statistics increases rapidly with telescope size making
  photonic astronomy very timely in an era of very large telescopes.

Title: QuantEYE, the quantum optics instrument for OWL
Authors: Barbieri, C.; da Deppo, V.; D'Onofrio, M.; Dravins, D.;
   Fornasier, S.; Fosbury, R. A. E.; Naletto, G.; Nilsson, R.; Occhipinti,
   T.; Tamburini, F.; Uthas, H.; Zampieri, L.
Bibcode: 2006IAUS..232..506B
Altcode:
  A brief description of the QuantEYE instrument proposed as a focal
  plane instrument for OWL is given. This instrument is dedicated to the
  very high speed observation of many active phenomena with a photon
  counting capability of up to 1GHz. The system samples the beam in
  10×10 subpupils, each focused on a fast photon counting detector.

Title: QuantEYE: The Quantum Optics Instrument for OWL
Authors: Dravins, D.; Barbieri, C.; Fosbury, R. A. E.; Naletto, G.;
   Nilsson, R.; Occhipinti, T.; Tamburini, F.; Uthas, H.; Zampieri, L.
Bibcode: 2005astro.ph.11027D
Altcode:
  QuantEYE is designed to be the highest time-resolution instrument
  on ESO:s planned Overwhelmingly Large Telescope, devised to explore
  astrophysical variability on microsecond and nanosecond scales, down to
  the quantum-optical limit. Expected phenomena include instabilities of
  photon-gas bubbles in accretion flows, p-mode oscillations in neutron
  stars, and quantum-optical photon bunching in time. Precise timescales
  are both variable and unknown, and studies must be of photon-stream
  statistics, e.g., their power spectra or autocorrelations. Such
  functions increase with the square of the intensity, implying an
  enormously increased sensitivity at the largest telescopes. QuantEYE
  covers the optical, and its design involves an array of photon-counting
  avalanche-diode detectors, each viewing one segment of the OWL entrance
  pupil. QuantEYE will work already with a partially filled OWL main
  mirror, and also without [full] adaptive optics.

Title: Report by the ESA-ESO Working Group on Extra-Solar Planets
Authors: Perryman, M.; Hainaut, O.; Dravins, D.; Leger, A.;
   Quirrenbach, A.; Rauer, H.; Kerber, F.; Fosbury, R.; Bouchy, F.;
   Favata, F.; Fridlund, M.; Gilmozzi, R.; Lagrange, A. -M.; Mazeh, T.;
   Rouan, D.; Udry, S.; Wambsganss, J.
Bibcode: 2005astro.ph..6163P
Altcode:
  Various techniques are being used to search for extra-solar planetary
  signatures, including accurate measurement of radial velocity and
  positional (astrometric) displacements, gravitational microlensing,
  and photometric transits. Planned space experiments promise a
  considerable increase in the detections and statistical knowledge
  arising especially from transit and astrometric measurements over the
  years 2005-15, with some hundreds of terrestrial-type planets expected
  from transit measurements, and many thousands of Jupiter-mass planets
  expected from astrometric measurements. Beyond 2015, very ambitious
  space (Darwin/TPF) and ground (OWL) experiments are targeting direct
  detection of nearby Earth-mass planets in the habitable zone and the
  measurement of their spectral characteristics. Beyond these, `Life
  Finder' (aiming to produce confirmatory evidence of the presence of
  life) and `Earth Imager' (some massive interferometric array providing
  resolved images of a distant Earth) appear as distant visions. This
  report, to ESA and ESO, summarises the direction of exo-planet research
  that can be expected over the next 10 years or so, identifies the
  roles of the major facilities of the two organisations in the field,
  and concludes with some recommendations which may assist development
  of the field. The report has been compiled by the Working Group members
  and experts over the period June-December 2004.

Title: ESA-ESO Working Group on "Extra-solar Planets"
Authors: Perryman, M.; Hainaut, O.; Dravins, D.; Leger, A.;
   Quirrenbach, A.; Rauer, H.; Kerber, F.; Fosbury, R.; Bouchy, F.;
   Favata, F.; Fridlund, M.; Gilmozzi, R.; Lagrange, A. -M.; Mazeh, T.;
   Rouan, D.; Udry, S.; Wambsganss, J.
Bibcode: 2005ewg1.rept.....P
Altcode:
  No abstract at ADS

Title: Wavelength shifts in solar-type spectra
Authors: Dravins, D.; Lindegren, L.; Ludwig, H. -G.; Madsen, S.
Bibcode: 2005ESASP.560..113D
Altcode: 2004astro.ph..9212D; 2005csss...13..113D
  Spectral-line displacements away from the wavelengths naively expected
  from the Doppler shift caused by stellar radial motion may originate as
  convective shifts (correlated velocity and brightness patterns in the
  photosphere), as gravitational redshifts, or perhaps be induced by wave
  motions. Absolute lineshifts, in the past studied only for the Sun, are
  now accessible also for other stars thanks to astrometric determination
  of stellar radial motion, and spectrometers with accurate wavelength
  calibration. Comparisons between spectroscopic apparent radial
  velocities and astrometrically determined radial motions reveal greater
  spectral blueshifts in F-type stars than in the Sun (as theoretically
  expected from their more vigorous convection), further increasing in
  A-type stars (possibly due to atmospheric shockwaves). An important
  near-future development to enable a further analysis of stellar surface
  structure will be the study of wavelength variations across spatially
  resolved stellar disks, e.g., the center-to-limb wavelength changes
  along a stellar diameter, and their spatially resolved time variability.

Title: Intrinsic Wavelength Shifts in Stellar Spectra
Authors: Dravins, D.; Lindegren, L.; Ludwig, H. -G.; Madsen, S.
Bibcode: 2004AAS...20517004D
Altcode: 2004BAAS...36.1624D
  Wavelengths of stellar spectral lines do not have the precise values
  `naively' expected from laboratory wavelengths merely Doppler-shifted
  by stellar radial motion. Slight displacements may originate as
  convective shifts (correlated velocity and brightness patterns in the
  photosphere), as gravitational redshifts, or perhaps be induced by wave
  motions. Intrinsic lineshifts thus reveal stellar surface structure,
  while possible periodic changes (during a stellar activity cycle,
  say) need to be segregated from variability induced by orbiting
  exoplanets. <P />Absolute lineshifts can now be studied also in some
  stars other than the Sun, thanks to astrometric determinations of
  stellar radial motion. Comparisons between spectroscopic apparent radial
  velocities and astrometrically determined radial motions reveal greater
  spectral blueshifts in F-type stars than in the Sun (as theoretically
  expected from their more vigorous convection), further increasing
  in A-type stars (possibly due to atmospheric shockwaves). <P />Solar
  spectral atlases, and high-resolution spectra (from UVES on ESO VLT) of
  a dozen solar-type stars are being surveyed for `unblended' photospheric
  lines of most atomic species with accurate laboratory wavelengths
  available. One aim is to understand the ultimate information content
  of stellar spectra, and in what detail it will be feasible to verify
  models of stellar atmospheric hydrodynamics. These may predict line
  asymmetries (bisectors) and shifts for widely different classes of
  lines, but there will not result any comparison with observations if
  such lines do not exist in real spectra. <P />An expected near-future
  development in stellar physics is spatially resolved spectroscopy across
  stellar disks, enabled by optical interferometry and adaptive optics
  on very large telescopes. Stellar surface structure manifests itself
  in the center-to-limb wavelength changes along a stellar diameter,
  and their spatially resolved time variability, diagnostics which
  already now can be theoretically modeled.

Title: Absolute Wavelength Shifts- A New Diagnostic for Rapidly
    Rotating Stars
Authors: Dravins, D.
Bibcode: 2004IAUS..215...27D
Altcode: 2003astro.ph..2592D
  Accuracies reached in space astrometry now permit the accurate
  determination of astrometric radial velocities, without any use of
  spectroscopy. Knowing this true stellar motion, spectral shifts
  intrinsic to stellar atmospheres can be identified, for instance
  gravitational redshifts and those caused by velocity fields on
  stellar surfaces. The astrometric accuracy is independent of any
  spectral complexity, such as the smeared-out line profiles of rapidly
  rotating stars. Besides a better determination of stellar velocities,
  this permits more precise studies of atmospheric dynamics, such as
  possible modifications of stellar surface convection (granulation)
  by rotation-induced forces, as well as a potential for observing
  meridional flows across stellar surfaces.

Title: Intrinsic spectral blueshifts in rapidly rotating stars?
Authors: Madsen, Søren; Dravins, Dainis; Ludwig, Hans-Günter;
   Lindegren, Lennart
Bibcode: 2003A&A...411..581M
Altcode: 2003astro.ph..9346M
  Spectroscopic radial velocities for several nearby open clusters
  suggest that spectra of (especially earlier-type) rapidly rotating
  stars are systematically blueshifted by 3 km s<SUP>-1</SUP> or more,
  relative to the spectra of slowly rotating ones. Comparisons with
  astrometrically determined radial motions in the Hyades suggests this
  to be an absolute blueshift, relative to wavelengths naively expected
  from stellar radial motion and gravitational redshift. Analogous
  trends are seen also in most other clusters studied (Pleiades,
  Coma Berenices, Praesepe, alpha Persei, IC 2391, NGC 6475, IC 4665,
  NGC 1976 and NGC 2516). Possible mechanisms are discussed, including
  photospheric convection, stellar pulsation, meridional circulation,
  and shock-wave propagation, as well as effects caused by template
  mismatch in determining wavelength displacements. For early-type
  stars, a plausible mechanism is shock-wave propagation upward through
  the photospheric line-forming regions. Such wavelength shifts thus
  permit studies of certain types of stellar atmospheric dynamics and
  - irrespective of their cause - may influence deduced open-cluster
  membership (when selected from common velocity) and deduced cluster
  dynamics (some types of stars might show fortuitous velocity patterns).

Title: The fundamental definition of ``radial velocity''
Authors: Lindegren, Lennart; Dravins, Dainis
Bibcode: 2003A&A...401.1185L
Altcode: 2003astro.ph..2522L
  Accuracy levels of metres per second require the fundamental concept of
  ``radial velocity'' for stars and other distant objects to be examined,
  both as a physical velocity, and as measured by spectroscopic and
  astrometric techniques. Already in a classical (non-relativistic)
  framework the line-of-sight velocity component is an ambiguous concept,
  depending on whether, e.g., the time of light emission (at the object)
  or that of light detection (by the observer) is used for recording
  the time coordinate. Relativistic velocity effects and spectroscopic
  measurements made inside gravitational fields add further complications,
  causing wavelength shifts to depend, e.g., on the transverse velocity
  of the object and the gravitational potential at the source. Aiming
  at definitions that are unambiguous at accuracy levels of 1 m
  s<SUP>-1</SUP>, we analyse different concepts of radial velocity and
  their interrelations. At this accuracy level, a strict separation must
  be made between the purely geometric concepts on one hand, and the
  spectroscopic measurement on the other. Among the geometric concepts
  we define kinematic radial velocity, which corresponds most closely to
  the ``textbook definition'' of radial velocity as the line-of-sight
  component of space velocity; and astrometric radial velocity, which
  can be derived from astrometric observations. Consistent with these
  definitions, we propose strict definitions also of the complementary
  kinematic and astrometric quantities, namely transverse velocity and
  proper motion. The kinematic and astrometric radial velocities depend
  on the chosen spacetime metric, and are accurately related by simple
  coordinate transformations. On the other hand, the observational
  quantity that should result from accurate spectroscopic measurements
  is the barycentric radial-velocity measure. This is independent of the
  metric, and to first order equals the line-of-sight velocity. However,
  it is not a physical velocity, and cannot be accurately transformed
  to a kinematic or astrometric radial velocity without additional
  assumptions and data in modelling the process of light emission from
  the source, the transmission of the signal through space, and its
  recording by the observer. For historic and practical reasons, the
  spectroscopic radial-velocity measure is expressed in velocity units
  as cz<SUB>B</SUB>, where c is the speed of light and z<SUB>B</SUB> is
  the observed relative wavelength shift reduced to the solar-system
  barycentre, at an epoch equal to the barycentric time of light
  arrival. The barycentric radial-velocity measure and the astrometric
  radial velocity are defined by recent resolutions adopted by the
  International Astronomical Union (IAU), the motives and consequences
  of which are explained in this paper.

Title: Absolute Lineshifts - a New Diagnostic for Stellar
    Hydrodynamics
Authors: Dravins, D.
Bibcode: 2003IAUS..210P..E4D
Altcode: 2003astro.ph..2591D
  For hydrodynamic model atmospheres, absolute lineshifts are becoming an
  observable diagnostic tool beyond the classical ones of line-strength,
  -width, -shape, and -asymmetry. This is the wavelength displacement
  of different types of spectral lines away from the positions naively
  expected from the Doppler shift caused by stellar radial motion. Caused
  mainly by correlated velocity and brightness patterns in granular
  convection, such absolute lineshifts could in the past be studied
  only for the Sun (since the relative Sun-Earth motion, and the ensuing
  Doppler shift is known). For other stars, this is now becoming possible
  thanks to three separate developments: (a) Astrometric determination of
  stellar radial motion; (b) High-resolution spectrometers with accurate
  wavelength calibration, and (c) Accurate laboratory wavelengths for
  several atomic species. Absolute lineshifts offer a tool to segregate
  various 2- and 3-dimensional models, and to identify non-LTE effects
  in line formation.

Title: Commission 36: Theory of stellar atmospheres (Théorie des
    atmosphères stellaires)
Authors: Dravins, Dainis
Bibcode: 2003IAUTA..25..242D
Altcode: 2003IAUTr..25A.242D
  No abstract at ADS

Title: Critical science for the largest telescopes: science drivers
    for a 100m ground-based optical-IR telescope
Authors: Hawarden, Timothy G.; Dravins, Dainis; Gilmore, Gerard F.;
   Gilmozzi, Roberto; Hainaut, Olivier; Kuijken, K.; Leibindgut, Bruno;
   Merrifield, Michael; Queloz, Didier; Wyse, Rosie
Bibcode: 2003SPIE.4840..299H
Altcode:
  Extremely large filled-aperture ground-based optical-IR telescopes, or
  ELTs, ranging from 20 to 100m in diameter, are now being proposed. The
  all-important choice of the aperture must clearly be driven by the
  potential science offered. We here highlight science goals from the
  Leiden Workshop in May 2001 suggesting that for certain critical
  observations the largest possible aperture - assumed to be 100m
  (the proposed European OverWhelmingly Large telescope (OWL) - is
  strongly to be desired. Examples from a long list include: COSMOLOGY:
  * Identifying the first sources of ionisation in the universe, out to
  z &gt;=14 * Identifying and stufdying the first generation of dusty
  galaxies * More speculatively, observing the formation of the laws
  of physics, via the evolution of the fundamental physical contants
  in the very early Universe, by high-resolution spectroscopy of very
  distant quasars. NEARER GALAXIES: *Determining detailed star-formation
  histories of galaxies out to the Virtgo Cluster, and hence for all
  major galaxy types (not just those available close to the Local Group
  of galaxies). THE SOLAR SYSTEM: A 100-m telescope would do the work of
  a flotilla of fly-by space probes for investigations ranging from the
  evolution of planetary sutfaces and atmospheres to detailed surface
  spectroscopy of Kuiper Belt Objects. (Such studies could easily occupy
  it full-time.) EARTHLIKE PLANETS OF NEARBY STARS: A propsect so exciting
  as perhaps to justify the 100-m telescope on its own, is that of the
  direct detection of earthlike planets of solar-type stars by imaging,
  out to at least 25 parsecs (80 light years) from the sun, followed by
  spectroscopic and photometric searches for the signature of life on
  the surfaces of nearer examples.

Title: HARPS: ESO's coming planet searcher. Chasing exoplanets with
    the La Silla 3.6-m telescope
Authors: Pepe, F.; Mayor, M.; Rupprecht, G.; Avila, G.; Ballester,
   P.; Beckers, J. -L.; Benz, W.; Bertaux, J. -L.; Bouchy, F.; Buzzoni,
   B.; Cavadore, C.; Deiries, S.; Dekker, H.; Delabre, B.; D'Odorico,
   S.; Eckert, W.; Fischer, J.; Fleury, M.; George, M.; Gilliotte, A.;
   Gojak, D.; Guzman, J. -C.; Koch, F.; Kohler, D.; Kotzlowski, H.;
   Lacroix, D.; Le Merrer, J.; Lizon, J. -L.; Lo Curto, G.; Longinotti,
   A.; Megevand, D.; Pasquini, L.; Petitpas, P.; Pichard, M.; Queloz,
   D.; Reyes, J.; Richaud, P.; Sivan, J. -P.; Sosnowska, D.; Soto, R.;
   Udry, S.; Ureta, E.; van Kesteren, A.; Weber, L.; Weilenmann, U.;
   Wicenec, A.; Wieland, G.; Christensen-Dalsgaard, J.; Dravins, D.;
   Hatzes, A.; Kürster, M.; Paresce, F.; Penny, A.
Bibcode: 2002Msngr.110....9P
Altcode:
  An extensive review of past, present and future research on extrasolar
  planets is given in the article “Extrasolar Planets” by N. Santos
  et al. in the present issue of The Messenger. Here we want to mention
  only that the search for extrasolar planets and the interpretation of
  the scientific results have evolved in recent years into one of the
  most exciting and dynamic research topics in modern astronomy.

Title: Astrometric radial velocities. III. Hipparcos measurements
    of nearby star clusters and associations
Authors: Madsen, Søren; Dravins, Dainis; Lindegren, Lennart
Bibcode: 2002A&A...381..446M
Altcode: 2001astro.ph.10617M
  Radial motions of stars in nearby moving clusters are determined
  from accurate proper motions and trigonometric parallaxes, without
  any use of spectroscopy. Assuming that cluster members share the
  same velocity vector (apart from a random dispersion), we apply a
  maximum-likelihood method on astrometric data from Hipparcos to compute
  radial and space velocities (and their dispersions) in the Ursa Major,
  Hyades, Coma Berenices, Pleiades, and Praesepe clusters, and for the
  Scorpius-Centaurus, alpha Persei, and ``HIP 98321'' associations. The
  radial motion of the Hyades cluster is determined to within 0.4 km
  s<SUP>-1</SUP> (standard error), and that of its individual stars
  to within 0.6 km s<SUP>-1</SUP>. For other clusters, Hipparcos data
  yield astrometric radial velocities with typical accuracies of a
  few km s<SUP>-1</SUP>. A comparison of these astrometric values with
  spectroscopic radial velocities in the literature shows a good general
  agreement and, in the case of the best-determined Hyades cluster,
  also permits searches for subtle astrophysical differences, such as
  evidence for enhanced convective blueshifts of F-dwarf spectra, and
  decreased gravitational redshifts in giants. Similar comparisons for
  the Scorpius OB2 complex indicate some expansion of its associations,
  albeit slower than expected from their ages. As a by-product from
  the radial-velocity solutions, kinematically improved parallaxes
  for individual stars are obtained, enabling Hertzsprung-Russell
  diagrams with unprecedented accuracy in luminosity. For the Hyades
  (parallax accuracy 0.3 mas), its main sequence resembles a thin
  line, possibly with wiggles in it. Although this main sequence has
  underpopulated regions at certain colours (previously suggested to be
  ``Böhm-Vitense gaps''), such are not visible for other clusters,
  and are probably spurious. Future space astrometry missions carry
  a great potential for absolute radial-velocity determinations,
  insensitive to the complexities of stellar spectra. Based on
  observations by the ESA Hipparcos satellite. Extended versions of
  Tables \ref{tab1} and \ref{tab2} are available in electronic form
  at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.125.8)
  or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/381/446

Title: VizieR Online Data Catalog: Astrometric Radial
    Velocities. III. (Madsen+, 2002)
Authors: Madsen, S.; Dravins, D.; Lindegren, L.
Bibcode: 2001yCat..33810446M
Altcode:
  Astrometrically determined kinematic data are given for nearby
  clusters and associations, including astrometric radial velocities and
  kinematically improved parallaxes for individual stars. The astrometric
  radial velocities are determined independent of spectroscopy. Table 1
  gives the space velocities and internal velocity dispersions of the
  clusters and associations. The electronic Table1 (Table1.dat) is an
  extended version of Table 1 in the journal paper, now including the
  full covariances of the space velocity components as well as the space
  motion in spherical coordinates. Table 2 gives the astrometric radial
  velocities and kinematically improved parallaxes for the individual
  stars. The electronic Table 2 is an extended version of Table 2 in the
  journal paper, now including all clusters and associations studied;
  results using data from both the Hipparcos and Tycho-2catalogues, as
  well as the standard errors for all deduced quantities. The electronic
  Table 2 is divided into 10 sub-tables (table1a.dat through table2j.dat),
  one for each cluster or association. (11 data files).

Title: The Velocity Dispersion of the Hyades as a Function of Mass
    and Radius
Authors: Madsen, S.; Lindegren, L.; Dravins, D.
Bibcode: 2001ASPC..228..506M
Altcode: 2001dscm.conf..506M
  No abstract at ADS

Title: Quantum-Optical Signatures of Stimulated Emission
Authors: Dravins, D.
Bibcode: 2001ASPC..242..339D
Altcode: 2001ecom.conf..339D
  No abstract at ADS

Title: Division IV: Stars
Authors: Barbuy, Beatriz; Cram, L.; Dravins, D.; Evans, T. L.; Mathys,
   G.; Scarfe, C.; VandenBerg, D.
Bibcode: 2001IAUTB..24..157B
Altcode:
  No abstract at ADS

Title: Absolute Lineshifts as Signatures of Stellar Surface Convection
(CD-ROM Directory: contribs/dravins)
Authors: Dravins, D.
Bibcode: 2001ASPC..223..778D
Altcode: 2001csss...11..778D
  No abstract at ADS

Title: Avalanche diodes as photon-counting detectors in astronomical
    photometry
Authors: Dravins, Dainis; Faria, Daniel; Nilsson, Bo
Bibcode: 2000SPIE.4008..298D
Altcode:
  Photon-counting silicon avalanche photo-diodes (APDs) offer very
  high quantum efficiency, and might eventually replace photocathode
  detectors in high-speed photometry of astronomical objects. Laboratory
  studies have been performed on both passively and actively quenched
  APDs. Peculiarities of APDs include that the dark signal may
  exhibit bistability, with the count rate jumping between discrete
  levels. Following any photon detection, the detector itself emits some
  light, which might be confusing under certain conditions. Deadtimes and
  after pulsing properties appear favorable, but the small physical size
  of APDs causes challenges in optically matching them to the entrance
  pupils of large telescopes.

Title: Astrometric radial velocities. II. Maximum-likelihood
    estimation of radial velocities in moving clusters
Authors: Lindegren, Lennart; Madsen, Søren; Dravins, Dainis
Bibcode: 2000A&A...356.1119L
Altcode:
  Accurate proper motions and trigonometric parallaxes of stars in
  nearby open clusters or associations permit to determine their space
  motions relative to the Sun, without using spectroscopy for their
  radial-velocity component. This assumes that the member stars share
  the same mean velocity vector, apart from a (small) random velocity
  dispersion. We present a maximum-likelihood formulation of this problem
  and derive an algorithm for estimating the space velocity and internal
  velocity dispersion of a cluster using astrometric data only. As
  a by-product, kinematically improved parallaxes and distances are
  obtained for the individual cluster stars. The accuracy of the method,
  its robustness, and its sensitivity to internal velocity fields, are
  studied through Monte Carlo simulations, using the Hyades as a test
  case. From Hipparcos data we derive the centroid velocity and internal
  velocity dispersion of the Hyades cluster. The astrometric radial
  velocities are obtained with a standard error of 0.47 km s<SUP>-1</SUP>
  for the cluster centroid, increasing to about 0.68 km s<SUP>-1</SUP>
  for the individual stars due to their peculiar velocities. If known
  binaries are removed, this improves to 0.60 km s<SUP>-1</SUP>. Based
  (in part) on observations by the ESA Hipparcos satellite

Title: Magnetic deformation of the white dwarf surface structure
Authors: Fendt, C.; Dravins, D.
Bibcode: 2000AN....321..193F
Altcode: 2000astro.ph..7387F
  The influence of strong, large-scale magnetic fields on the
  structure and temperature distribution in white dwarf atmospheres is
  investigated. Magnetic fields may provide an additional component
  of pressure support, thus possibly inflating the atmosphere
  compared to the non-magnetic case. Since the magnetic forces are
  not isotropic, atmospheric properties may significantly deviate from
  spherical symmetry. In this paper the magnetohydrostatic equilibrium
  is calculated numerically in the radial direction for either for
  small deviations from different assumptions for the poloidal current
  distribution. We generally find indication that the scale height of the
  magnetic white dwarf atmosphere enlarges with magnetic field strength
  and/or poloidal current strength. This is in qualitative agreement
  with recent spectropolarimetric observations of Grw+10<SUP>o</SUP>
  -8247. Quantitatively, we find for e.g. a mean surface poloidal
  field strength of 100 MG and a toroidal field strength of 2-10 MG
  an increase of scale height by a factor of 10. This is indicating
  that already a small deviation from the initial force-free dipolar
  magnetic field may lead to observable effects. We further propose
  the method of finite elements for the solution of the two-dimensional
  magnetohydrostatic equilibrium including radiation transport in the
  diffusive approximation. We present and discuss preliminary solutions,
  again indicating on an expansion of the magnetized atmosphere.

Title: Main sequences of nearby open clusters and OB associations
    from kinematic modelling of Hipparcos data
Authors: Madsen, S.; Lindegren, L.; Dravins, D.
Bibcode: 2000ASPC..198..137M
Altcode: 2000scac.conf..137M
  No abstract at ADS

Title: Commission 12: Solar Radiation and Structure (Radiation et
    Structure Solaires)
Authors: Foukal, Peter; Solanki, Sami; Mariska, J.; Baliunas, S.;
   Dravins, D.; Duvall, T.; Fang, C.; Gaizauskas, V.; Heinzel, P.;
   Kononovich, E.; Koutchmy, S.; Melrose, D.; Stix, M.; Suematsu, Y.;
   Deubner, F.
Bibcode: 2000IAUTA..24...73F
Altcode:
  No abstract at ADS

Title: Commission 36: Theory of Stellar Atmospheres: (Theorie des
    Atmospheres Stellaires)
Authors: Pallavicini, R.; Dravins, D.; Barbuy, B.; Cram, L.; Hubeny,
   I.; Owocki, S.; Saio, H.; Sasselov, D.; Spite, M.; Stepien, K.;
   Wehrse, R.
Bibcode: 2000IAUTA..24..219P
Altcode:
  No abstract at ADS

Title: Beyond imaging, spectroscopy and interferometry: Quantum
    optics at the largest telescopes
Authors: Dravins, D.
Bibcode: 2000ESOC...57...36D
Altcode: 2000elt..conf...36D
  No abstract at ADS

Title: Astrometric radial velocities. I. Non-spectroscopic methods
    for measuring stellar radial velocity
Authors: Dravins, Dainis; Lindegren, Lennart; Madsen, Søren
Bibcode: 1999A&A...348.1040D
Altcode: 1999astro.ph..7145D
  High-accuracy astrometry permits the determination of not only stellar
  tangential motion, but also the component along the line-of-sight. Such
  non-spectroscopic (i.e. astrometric) radial velocities are independent
  of stellar atmospheric dynamics, spectral complexity and variability,
  as well as of gravitational redshift. Three methods are analysed: (1)
  changing annual parallax, (2) changing proper motion and (3) changing
  angular extent of a moving group of stars. All three have significant
  potential in planned astrometric projects. Current accuracies are still
  inadequate for the first method, while the second is marginally feasible
  and is here applied to 16 stars. The third method reaches high accuracy
  (&lt;1 km s(-1) ) already with present data, although for some clusters
  an accuracy limit is set by uncertainties in the cluster expansion
  rate. Based (in part) on observations by the ESA Hipparcos satellite

Title: Exactly What Is Stellar 'Radial Velocity'?
Authors: Lindegren, L.; Dravins, D.; Madsen, S.
Bibcode: 1999ASPC..185...73L
Altcode: 1999IAUCo.170...73L; 1999psrv.conf...73L
  Accuracy levels of metres per second require the fundamental
  concept of 'radial velocity' to be examined, in particular due to
  relativistic velocity effects, and spectroscopic measurements made
  inside gravitational fields. Naively, 'radial velocity' equals the
  line-of-sight component of the stellar velocity vector, measured by
  the Doppler shifts of stellar spectral lines. Although many physical
  effects in stellar atmospheres contribute to the line shifts, those
  could in principle be corrected for, leaving the 'true' (centre-of-mass)
  velocity. However, also this concept becomes ambiguous at accuracy
  levels around 10-100 m/s. Radial velocity is the change in distance
  with respect to 'time'. But is this the time of light emission (at
  the star) or light reception (at the observer)? The former seems
  natural if radial velocity is considered a 'property' of the star,
  while the latter is more natural for the observer. The difference is
  of second order in velocity (v*v/c), exceeding 100 m/s for v &gt;
  173 km/s. Similar differences exist between the classical and the
  relativistic Doppler formulae, and depend on how the transverse
  Doppler effect is treated. Thus, the determination of the radial
  velocity component cannot be separated from the determination of the
  transverse one, requiring knowledge also of the stellar proper motion,
  and distance. Gravitational redshift caused by the Sun diminishes
  with distance as 1/r. At the solar surface (r = R<SUB>o</SUB>),
  it is 636 m/s, diminishing to 3 m/s at the Earth's distance (215
  R<SUB>o</SUB>). Thus, in principle, all stars will have such a blueshift
  component, if measured near the Earth. A general-relativistic treatment
  introduces additional complications, e.g. that the numerical velocities
  depend on the chosen metric. Also, variable relativistic delay along
  the light path would introduce line shifts, e.g. during microlensing
  events. Among the effects influencing the measurement of accurate line
  shifts, only local ones can be reliably calculated. These depend on
  the motion and gravitational potential of the observer relative to
  the desired reference frame, usually the solar system barycentre. We
  argue that the barycentric fractional wavelength shift z is therefore
  the proper observational quantity to be derived from spectroscopic
  measurements. However, this barycentric shift cannot be uniquely
  interpreted as a radial motion of the object. If velocity units are
  desired, this shift can be expressed as cz, analogous to the case
  in cosmology.

Title: Radial Velocities without Spectroscopy
Authors: Madsen, S.; Lindegren, L.; Dravins, D.
Bibcode: 1999ASPC..185...77M
Altcode: 1999IAUCo.170...77M; 1999psrv.conf...77M
  Accuracies in space astrometry now permit accurate determination of
  stellar radial velocity without using spectroscopy or invoking the
  Doppler principle. Already Hipparcos data permit accuracies of 100 m/s
  in some cases, while future space astrometry missions will enable such
  determinations for a broad range of stars. Fundamental radial-velocity
  standards have hitherto been limited to solar-system objects, in
  particular asteroids, whose space motions can be derived with very
  high accuracy without the use of spectroscopic data. Astrometric
  techniques are now extending the realm of such geometrically determined
  radial velocities to many nearby stars. Among astrometric measures
  for radial-velocity determination, the most direct is the secular
  change in trigonometric parallax due to the radial displacement
  of a star. Although this requires extremely accurate measurements
  over years or decades, it should become feasible with planned space
  missions. For Barnard's star (parallax 549 mas, V_<SUB>r</SUB> = -110
  km/s), the expected parallax change is 34 microarcsec/year. Assuming
  that a star moves uniformly through space, its velocity can also be
  derived from the secular change in its proper motion (which varies
  due to the observer). For astrometric missions now being planned, this
  method should yield space velocities to better than 100 m/s for several
  nearby high-velocity stars. A third astrometric method that already
  has been applied using data from the Hipparcos mission, concerns the
  secular change of the angular extent of moving star clusters. Since all
  cluster stars share the same (average) velocity vector, the cluster's
  apparent size changes as it moves in the radial direction. This relative
  change (revealed by the proper-motion vectors towards the cluster apex)
  corresponds to the relative change in distance. Since the individual
  stellar distances are known from parallaxes, their radial velocities
  follow. Applying this moving-cluster method to Hipparcos data, radial
  velocities have now been derived for many stars in the Hyades and in
  the Ursa Major clusters, reaching accuracies between 100-400 m/s. The
  comparison of these values with precise spectroscopic measurements
  reveals wavelength shifts not caused by stellar motion, as discussed
  elsewhere in this colloquium.

Title: Astrometric versus Spectroscopic Radial Velocities
Authors: Dravins, D.; Gullberg, D.; Lindegren, L.; Madsen, S.
Bibcode: 1999ASPC..185...41D
Altcode: 1999IAUCo.170...41D; 1999psrv.conf...41D
  The radial velocity of a star, as deduced from wavelength shifts, does
  not merely contain the true velocity of the stellar center of mass
  but also components arising from dynamics in the star's atmosphere,
  gravitational redshifts, and other effects. For the Sun, the segregation
  of such effects has been possible because the relative Sun-Earth motion
  is accurately known from planetary system dynamics, and does not have to
  be deduced from asymmetric and shifted line profiles. For other stars,
  accurate determinations of their true radial motion have only recently
  become feasible with space astrometry. Data from Hipparcos permit
  accurate such determinations for stars in nearby moving clusters such as
  Ursa Major and the Hyades (Dravins et al., in Proc. Hipparcos - Venice
  '97, ESA SP-402, p.733, 1997). When a star cluster (whose stars share
  the same velocity vector) moves in the radial direction, its angular
  size changes, as measured by stellar proper-motion vectors. This
  rate of change equals the time derivative of the [known] distance,
  i.e. the radial velocity. Future astrometric missions will extend
  astrometric radial-velocity determinations also to individual field
  stars with measurable changes in parallax and proper motion. For these
  stars with astrometric radial-velocity determinations, a parallel
  spectroscopic program has recently been completed at Haute-Provence
  Observatory, using its ELODIE radial-velocity spectrometer. Almost
  100 program stars of many different spectral types were observed
  under very good signal-to-noise conditions. Work is in progress to
  compare the spectroscopic radial velocities with the astrometric
  values, and to search for systematic line shift differences between
  groups of different spectral lines (with respect to line-strength,
  excitation potential, or wavelength region). The overall stability of
  ELODIE spectra reaches 10 m/s; the expected spectroscopic precision
  for groups of 100 selected lines in any one star is about 50 m/s;
  the accuracy in astrometric radial velocity reaches 200 m/s, while
  hydrodynamic models of stellar atmospheres predict differences
  on the order of 1 km/s in convective line shifts between different
  stars. Gravitational redshifts are of comparable magnitude. This program
  thus aims at identifying signatures of stellar surface structure from
  line shift patterns, at finding differences in gravitational redshift
  between different spectral types, and at improving the absolute
  calibration of velocity values for stars of different rotational
  velocity and spectral complexity. The program includes not only
  Hyades and Ursa Major stars, but also IAU radial-velocity standards,
  metal-deficient stars, and others. For a further discussion, see:
  &lt;A HREF="http://www.astro.lu.se/dainis/HTML/ASTROMET.html"&gt;
  Discussion &lt;/A&gt;

Title: Stellar Surface Convection, Line Asymmetries, and Wavelength
    Shifts
Authors: Dravins, D.
Bibcode: 1999ASPC..185..268D
Altcode: 1999IAUCo.170..268D; 1999psrv.conf..268D
  When observed under sufficient resolution, practically all stellar
  spectral lines prove to be slightly asymmetric. Absorption lines in
  cooler stars form in inhomogeneous atmospheres, affected by surface
  convection (stellar granulation). Asymmetries and wavelength shifts
  originate from correlated velocity and brightness patterns: rising (
  = blueshifted) elements are hot (=bright), and convective blueshifts
  result from a larger contribution of such blueshifted photons than
  of redshifted ones from the sinking and cooler (=darker) gas. For
  the Sun, the effect is around 300 m/s. High-excitation lines form
  predominantly in the hottest elements and show a more pronounced
  blueshift. The effects are predicted to be greater in F-type stars,
  and in giants. In the presence of magnetic fields, convection is
  disturbed and granules do not develop to equally large size or
  velocity amplitude, resulting in smaller blueshifts (by perhaps 10%
  or 30 m/s) during the years around activity maximum in the 11-year
  solar cycle. Such activity-cycle induced lineshift variations must
  of course be segregated from stellar velocity signals in searches for
  exoplanets with comparable periods. While line asymmetries and shifts
  may appear as a noise source in determining stellar motions, they are
  an important observational signature for constraining three-dimensional
  (magneto-) hydrodynamic models of stellar atmospheres. These are capable
  of predicting not only line-widths and shapes, but also second-order
  quantities such as asymmetries and shifts. A high measuring precision
  reveals properties of the stellar surface structure also through the
  temporal variability of stellar line wavelengths. On the visible solar
  disk, there are on the order of 10**6 granules, each with a velocity
  amplitude of some 2 km/s, evolving over some 10 min. In integrated
  sunlight, this amplitude is reduced by a factor of about sqrt(10**6)
  to perhaps 2 m/s. Stars with larger velocity amplitudes and/or fewer
  granules will show correspondingly greater fluctuations, observable
  already with current techniques. Until the present, wavelength-shift
  observations have generally been for unresolved (i.e. spatially
  averaged) stellar disks. A major future development will be the study
  of wavelength variations across spatially resolved stars, e.g. the
  center-to-limb changes along the equatorial and polar diameters, and
  their spatially resolved time variability. Adaptive optics on very
  large telescopes, long-baseline optical interferometry, and optical
  aperture synthesis will soon open up new vistas of stellar atmospheric
  physics through radial-velocity observations.

Title: Atmospheric Intensity Scintillation of Stars (PASP, 110, 610
    [1998]).
Authors: Dravins, Dainis; Lindegren, Lennart; Mezey, Eva; Young,
   Andrew T.
Bibcode: 1998PASP..110.1118D
Altcode:
  In the paper ``Atmospheric Intensity Scintillation of
  Stars. III. Effects for Different Telescope Apertures'' by Dainis
  Dravins, Lennart Lindegren, Eva Mezey, and Andrew T. Young (PASP, 110,
  610 [1998]), there is a typographical error on page 625, column (2), 17
  lines from bottom. The expression giving the frequencies for which the
  previous equation (10) is valid has the superfluous characters ``3D''
  on its right-hand side, which thus should read only ``1 Hz.'' The error
  was caused in proof stage from inconsistencies in e-mail sending and
  receiving ``standards.''

Title: Atmospheric Intensity Scintillation of Stars. III. Effects
    for Different Telescope Apertures
Authors: Dravins, Dainis; Lindegren, Lennart; Mezey, Eva; Young,
   Andrew T.
Bibcode: 1998PASP..110..610D
Altcode:
  Stellar intensity scintillation in the optical was extensively
  studied at the astronomical observatory on La Palma (Canary
  Islands). Atmospheric turbulence causes ``flying shadows'' on the
  ground, and intensity fluctuations occur both because this pattern is
  carried by winds and is intrinsically changing. Temporal statistics and
  time changes were treated in Paper I, and the dependence on optical
  wavelength in Paper II. This paper discusses the structure of these
  flying shadows and analyzes the scintillation signals recorded in
  telescopes of different size and with different (secondary-mirror)
  obscurations. Using scintillation theory, a sequence of power spectra
  measured for smaller apertures is extrapolated up to very large (8 m)
  telescopes. Apodized apertures (with a gradual transmission falloff
  near the edges) are experimentally tested and modeled for suppressing
  the most rapid scintillation components. Double apertures determine
  the speed and direction of the flying shadows. Challenging photometry
  tasks (e.g., stellar microvariability) require methods for decreasing
  the scintillation ``noise.'' The true source intensity I(lambda) may
  be segregated from the scintillation component DeltaI(t,lambda,x,y)
  in postdetection computation, using physical modeling of the temporal,
  chromatic, and spatial properties of scintillation, rather than treating
  it as mere ``noise.'' Such a scheme ideally requires multicolor
  high-speed (&lt;~10 ms) photometry on the flying shadows over the
  spatially resolved (&lt;~10 cm) telescope entrance pupil. Adaptive
  correction in real time of the two-dimensional intensity excursions
  across the telescope pupil also appears feasible, but would probably
  not offer photometric precision. However, such ``second-order''
  adaptive optics, correcting not only the wavefront phase but also
  scintillation effects, is required for other critical tasks such as the
  direct imaging of extrasolar planets with large ground-based telescopes.

Title: Beta Hydri (G2 IV): a revised age for the closest subgiant
Authors: Dravins, D.; Lindegren, L.; Vandenberg, D. A.
Bibcode: 1998A&A...330.1077D
Altcode:
  The secular evolution of solar-type atmospheres may be studied through
  comparisons of the current Sun with old solar-type stars of known
  age. Among the few such stars in the solar Galactic neighborhood,
  beta Hydri (G2 IV) stands out as a normal single star with an advanced
  age. Previous age determinations ( =~ 9.5 Gy) were based on the old
  ground-based parallax of 153 mas. The new Hipparcos value of 133.78+/-
  0.51 mas implies an absolute magnitude M_V=3.43 +/- 0.01, 0.3 mag
  brighter than previously believed. New evolutionary calculations produce
  best-fit models with ages around 6.7 Gy. Although the Hipparcos data
  thus lead to a significant reduction of its estimated age, beta Hyi
  remains an old star. Based on observations made with the ESA Hipparcos
  astrometry satellite

Title: Astrometric Radial Velocities from HIPPARCOS
Authors: Dravins, D.; Lindegren, L.; Madsen, S.; Holmberg, J.
Bibcode: 1998HiA....11..564D
Altcode:
  No abstract at ADS

Title: Spectroscopic Radial Velocities: Photospheric Lineshifts
    Calibrated by HIPPARCOS
Authors: Gullberg, D.; Dravins, D.
Bibcode: 1998HiA....11..564G
Altcode:
  No abstract at ADS

Title: Beta Hydri (G2 IV): A Revised Age for the Closest Subgiant
Authors: Dravins, D.; Lindegren, L.; Vandenberg, D. A.
Bibcode: 1997ESASP.402..397D
Altcode: 1997hipp.conf..397D
  The secular evolution of solar-type atmospheres may be studied through
  comparisons of the current Sun with old solar-type stars of known
  age. Among the few such stars in the solar Galactic neighborhood,
  beta Hydri (G2 IV) stands out as a normal single star with an advanced
  age. Previous age determinations (~= 9.5 Gy) were based on the old
  ground-based parallax of 153 mas. The new Hipparcos value of 133.78
  +/- 0.51 mas implies an absolute magnitude M_V=3.43 +/- 0.01, 0.3 mag
  brighter than previously believed. New evolutionary calculations produce
  best-fit models with ages around 6.7 Gy. Although the Hipparcos data
  thus lead to a significant reduction of its age, beta Hyi remains an
  old star.

Title: Astrometric Radial Velocities from HIPPARCOS
Authors: Dravins, D.; Lindegren, L.; Madsen, S.; Holmberg, J.
Bibcode: 1997ESASP.402..733D
Altcode: 1997hipp.conf..733D
  Space astrometry now permits accurate determinations of stellar
  radial motion, without using spectroscopy. Using Hipparcos data,
  this is possible for stars in nearby moving clusters, where all stars
  share nearly the same space velocity. A maximum-likelihood method
  has been developed to yield kinematic cluster parameters (including
  the internal velocity dispersion) purely from parallaxes and proper
  motions. The deduced astrometric radial velocities of the Ursa Major
  open cluster and the Hyades have inaccuracies of 0.3 and 0.4 km/s,
  respectively, and the internal cluster velocity dispersions are
  found to be 0.66 +/- 0.10 and 0.25 +/- 0.04 km/s (consistent with
  random stellar motions). Remaining errors arise from uncertainties
  in excluding binary stars. The errors get worse for the more distant
  Coma Berenices cluster. The fitting of cluster parameters includes
  all individual stellar distances. The constraint of a uniform average
  cluster velocity markedly improves the parallax precisions (roughly by
  a factor two), compared with Hipparcos data for individual stars. The
  HR diagram for the Hyades now reveals a very narrow main sequence line
  (not band), even suggesting some wiggles in it. Discrepancies between
  astrometric and spectroscopic radial velocities reveal effects (other
  than stellar motion) that affect wavelength positions of spectral
  lines. Such are caused by stellar pulsation, surface convection,
  and by gravitational redshifts. A parallel programme is obtaining and
  analysing high-precision spectroscopic radial velocities for different
  classes of spectral lines in these programme stars.

Title: Atmospheric Intensity Scintillation of Stars. II. Dependence
    on Optical Wavelength
Authors: Dravins, D.; Lindegren, L.; Mezey, E.; Young, A. T.
Bibcode: 1997PASP..109..725D
Altcode:
  Atmospheric intensity scintillation of stars on milli- and microsecond
  time scales was extensively measured at the astronomical observatory on
  La Palma (Canary Island). Scintillation statistics and temporal changes
  were discussed in Paper I, while this paper shows how scintillation
  depends on optical wavelength. Such effects originate from the
  changing refractive index of air, and from wavelength-dependent
  diffraction in atmospheric inhomogeneities. The intensity variance
  \sigma2/I increases for shorter wavelengths, at small zenith distances
  approximately consistent with a theoretical \lambda $^{-7/6}$ slope,
  but with a tendency for a somewhat weaker dependence. Scintillation
  in the blue is more rapid than in the red. The increase with
  wavelength of autocorrelation time scales (roughly proportional to
  $sqrt{\lambda}$ is most pronounced in very small apertures, but was
  measured up to \o 20 cm. Scintillation at different wavelengths
  is not simultaneous: atmospheric chromatic dispersion stretches
  the atmospherically induced 'flying shadows' into 'flying spectra'
  on the ground. As the 'shadows' fly past the telescope aperture,
  a time delay appears between fluctuations at different wavelengths
  whenever the turbulence-carrying winds have components parallel to the
  direction of dispersion. These effects increase with zenith distance
  (reaching \approx 100 ms cross-correlation delay between blue and red
  at Z = 60°), and also with increased wavelength difference. This time
  delay between scintillation in different colors is a property of the
  atmospheric flying shadows, and thus a property that remains unchanged
  even in very large telescopes. However, the wavelength dependence of
  scintillation amplitude and time scale is 'fully' developed only in
  small telescope apertures (less than about 5 cm), the scales where
  the 'flying shadows' on the Earth's surface become resolved. Although
  these dependences rapidly vanish after averaging in larger apertures,
  an understanding of chromatic effects may still be needed for the
  most accurate photometric measurements. These will probably require
  a sampling of the [stellar] signal with full spatial, temporal and
  chromatic resolution to segregate the scintillation signatures from
  those of astrophysical variability. (SECTION: Atmospheric Phenomena
  and Seeing)

Title: Atmospheric Intensity Scintillation of Stars, I. Statistical
    Distributions and Temporal Properties
Authors: Dravins, Dainis; Lindegren, Lennart; Mezey, Eva; Young,
   Andrew T.
Bibcode: 1997PASP..109..173D
Altcode:
  Stellar intensity scintillation in the optical was extensively
  studies at the astronomical observatory on La Palma (Canary
  Islands). Photon-counting detectors and digital signal processors
  recorded temporal auto-and cross-correlation functions, power spectra,
  and probability distributions. This first paper of a series treats
  the temporal properties of scintillation, ranging from microseconds
  to seasons of year. Previous studies, and the mechanisms producing
  scintillation are reviewed. Atmospheric turbulence causes 'flying
  shadows' on the ground, and intensity fluctuations occur both because
  this pattern is carried by winds, and is intrinsically changing. On
  very short timescales, a break in the correlation functions around
  300 mus may be a signature of an inner scale (approx. 3 mm in the
  shadow pattern at windspeeds of ms -1). On millisecond timescales,
  the autocorrelation decreases for smaller telescope apertures until
  approx. 5 cm, when the 'flying shadows' become resolved. During
  any night, timescales and amplitudes evolve on scales of tens of
  minutes. In good summer conditions, the flying-shadow patterns are
  sufficiently regular and long-lived to show anti-correlation dips
  in autocorrelation functions, which in winter are smeared out by
  apparent wind shear. Recordings of intensity variance together with
  stellar speckle images suggest some correlation between good [angular]
  seeing and large scintillation. Near zenith, the temporal statistics
  (with up to 12:th order moments measured)is best fitted by a Beta
  distribution of the second kind (F-distribution), although it is well
  approximated by log-normal functions, evolving with time. (SECTION:
  Atmospheric Phenomena and Seeing)

Title: Astrometric Radial Velocities from HIPPARCOS
Authors: Dravins, D.; Lindegren, L.; Madsen, S.; Holmberg, J.
Bibcode: 1997IAUJD..14E..33D
Altcode:
  Space astrometry now permits accurate determinations of stellar radial
  motion, without using spectroscopy. Although the feasibility of deducing
  astrometric radial velocities from geometric projection effects was
  realized already by Schlesinger (1917), only with Hipparcos has it
  become practical. Such a program has now been carried out for the
  moving clusters of Ursa Major, Hyades, and Coma Berenices. Realized
  inaccuracies reach 500 m/s, or slightly better (Dravins et
  al. 1997). Discrepancies between astrometric and spectroscopic radial
  velocities reveal effects (other than stellar motion) that affect
  wavelength positions of spectral lines. Such are caused by stellar
  surface convection, and by gravitational redshifts. A parallel program
  (Gullberg &amp; Dravins 1997) is analyzing high-precision spectroscopic
  radial velocities for different spectral lines in these stars, using
  the ELODIE radial-velocity instrument at Haute-Provence.

Title: Spectroscopic Radial Velocities: Photospheric Lineshifts
    Calibrated by HIPPARCOS
Authors: Gullberg, D.; Dravins, D.
Bibcode: 1997IAUJD..14E..32G
Altcode:
  Stellar wavelengths depend not only on the star's motion. Until
  recently, accurate studies of shifts not caused by radial motion
  were feasible only for the Sun. Solar lineshifts are interpreted as
  gravitational redshift (636 m/s) and convective blueshifts (~400
  m/s; caused by velocity-brightness correlations). In other stars,
  such effects may be greater (Dravins &amp; Nordlund 1990). Accurate
  astrometric radial velocities are now available from Hipparcos
  (Dravins et al. 1997a; 1997b), permitting studies of such shifts
  also in some other stars. For such stars in the open clusters of
  Hyades, Ursa Major and Coma Berenices, a spectroscopic program is
  in progress, analyzing wavelength shifts in groups of lines with
  different strengths, excitation potentials, etc., using the ELODIE
  high-precision radial-velocity instrument (Baranne et al., 1996) at
  Haute-Provence. Baranne, A. et al., 1996, A&amp;AS 119, 373 Dravins,
  D., Nordlund, AA., 1990, A&amp;A 228, 203 Dravins, D., Lindegren, L.,
  Madsen, S., Holmberg, J., 1997a, in ESA SP-402, Hipparcos Symposium,
  Venice Dravins, D., Lindegren, L., Madsen, S., Holmberg, J., 1997b,
  IAU General Assembly, Kyoto

Title: Observed and computed spectral line profiles
Authors: Dravins, D.
Bibcode: 1996IAUS..176..519D
Altcode:
  No abstract at ADS

Title: Optical Observations on Milli-, Micro-, and Nanosecond
    Timescales
Authors: Dravins, D.; Lindegren, L.; Mezey, E.
Bibcode: 1995LNP...454..129D
Altcode: 1995flfl.conf..129D
  Instrumentation and observing methods are developed for optical
  high-speed astrophysics, aiming at exploring milli-, micro-, and
  nanosecond variability. Such rapid fluctuations can be expected from
  instabilities in accretion flows, and in the fine structure of photon
  emission. For the optical, we have constructed a dedicated instrument,
  whose first version was tested on La Palma to study atmospheric
  scintillation on very short timescales. A second version is now under
  development, using photon-counting avalanche photodiodes as detectors.

Title: Observational Astrophysics on Milli-, Micro-, and Nanosecond
    Timescales
Authors: Dravins, D.; Lindegren, L.; Mezey, E.
Bibcode: 1995svlt.conf..139D
Altcode:
  No abstract at ADS

Title: Spectroscopic measurements of stellar rotation
Authors: Dravins, D.
Bibcode: 1995HiA....10..403D
Altcode:
  No abstract at ADS

Title: Astrophysics on its shortest timescales.
Authors: Dravins, D.
Bibcode: 1994Msngr..78....9D
Altcode:
  The VLT will permit enormously more sensitive searches for high-speed
  phenomena in astrophysics.

Title: Optical astronomy on milli-, micro-, and nanosecond timescales
Authors: Dravins, Dainis; Hagerbo, Hans O.; Lindegren, Lennart; Mezey,
   Eva; Nilsson, Bo
Bibcode: 1994SPIE.2198..289D
Altcode:
  Instrumentation and observing methods are being developed for a program
  in optical high-speed astrophysics, an exploratory project entering the
  domains of milli-, micro-, and nanosecond variability. Current studies
  include accretion flows around compact objects, stellar scintillation,
  and astronomical quantum optics. To study such rapid phenomena is not
  possible everywhere in the spectrum (e.g., X-ray studies are constrained
  by the photon count rates feasible with current spacecraft). The ground-
  based optical is a promising region, for which we have constructed a
  dedicated instrument, QVANTOS ('Quantum-Optical Spectrometer'). It
  was designed for real-time handling of large amounts of data, for
  observing also faint sources, and with a time resolution that can be
  extended to reveal quantum properties of light, such as the bunching
  of photons in time. Its first version was used to study atmospheric
  scintillation on timescales between 100 milli- and 100 nsec, utilizing
  some 25 full nights at a telescope on La Palma (Canary Islands). An
  understanding of the atmosphere is required to segregate astrophysical
  variability from terrestial effects, and to find optimal observing
  strategies. For very high time resolution, light curves are of little
  use, and statistical functions of variability have to be measured. The
  noise in such functions decreases dramatically with increased light
  collecting power, making very large telescopes much more sensitive
  for the study of rapid variability than ordinary-sized ones.

Title: Instrumental effects in stellar spectroscopy
Authors: Dravins, D.
Bibcode: 1994ASIC..436..269D
Altcode: 1994iltm.conf..269D
  No abstract at ADS

Title: The Distant Future of Solar Activity: A Case Study of beta
    Hydri. II. Chromospheric Activity and Variability
Authors: Dravins, D.; Linde, P.; Fredga, K.; Gahm, G. F.
Bibcode: 1993ApJ...403..396D
Altcode:
  A detailed comparison of the present sun with the very old star Beta
  Hyi (G2 IV) is presented in order to study the secular evolution
  of solar-type chromospheres, with emphasis placed on chromospheric
  features and their time variability. High-resolution Ca II H and
  K profiles show the emission to be about half that for the sun, but
  with the same sense of violet-red asymmetry. The emission's wavelength
  width is slightly broader, consistent with the Wilson-Bappu relation
  for this slightly more luminous star. Mg II h and k profiles also
  exhibit an emission weaker than the sun, but with the opposite sense
  of asymmetry, probably altered by absorption in a nearby interstellar
  cloud. The emission variations are small and are characterized by
  smooth and systematic change in the line profiles from year to year,
  suggesting continuous changes in the chromospheric structure, rather
  than the sudden emergence of growth of active regions.

Title: Atmospheric Intensity Scintillation of Stars on Millisecond
    and Microsecond Time Scales
Authors: Dravins, D.; Lindegren, L.; Mezey, E.
Bibcode: 1993spct.conf..113D
Altcode: 1993IAUCo.136..113D
  No abstract at ADS

Title: The Distant Future of Solar Activity: A Case Study of beta
    Hydri. I. Stellar Evolution, Lithium Abundance, and Photospheric
    Structure
Authors: Dravins, D.; Lindegren, L.; Nordlund, A.; Vandenberg, D. A.
Bibcode: 1993ApJ...403..385D
Altcode:
  A detailed comparison of the current sun (G2 V) with the very old
  solar-type star Beta Hyi (G2 IV) is presented in order to study the
  postmain-sequence evolution of stellar activity and of nonthermal
  processes in solar-type atmospheres. Special attention is given to
  general stellar properties and the deeper atmosphere of Beta Hyi. A
  critical review of data from various sources is presented, and the
  age of Beta Hyi is determined from evolutionary models to 9.5 +/-
  0.8 Gyr. The relatively high lithium abundance may be a signature of
  the early subgiant stage, when lithium that once diffused to beneath
  the main-sequence convection zone is dredged up to the surface as the
  convection zone deepens. Numerical simulations of the 3D photospheric
  hydrodynamics show typical granules to be significantly larger (a
  factor of about 5) than solar ones.

Title: The Distant Future of Solar Activity: A Case Study of beta
    Hydri. III. Transition Region, Corona, and Stellar Wind
Authors: Dravins, D.; Linde, P.; Ayres, T. R.; Linsky, J. L.;
   Monsignori-Fossi, B.; Simon, T.; Wallinder, F.
Bibcode: 1993ApJ...403..412D
Altcode:
  The paper investigates the secular decay of solar-type activity
  through a detailed comparison of the present sun with the very old
  solar-type star, Beta Hyi, taken as a proxy of the future sun. Analyses
  of successive atmospheric layers are presented, with emphasis of the
  outermost parts. The FUV emission lines for the transition zone are
  among the faintest so far seen in any solar-type star. The coronal soft
  X-ray spectrum was measured through different filters on EXOSAT and
  compared to simulated X-ray observations of the sun seen as a star. The
  flux from Beta Hyi is weaker than that from the solar corona and has
  a different spectrum. It is inferred that a thermally driven stellar
  wind can no longer be supported, which removes the mechanism from
  further rotational braking of the star through a magnetic stellar wind.

Title: High Resolution Spectroscopy of Stellar Velocity Signatures
Authors: Dravins, D.
Bibcode: 1992ESOC...40...55D
Altcode: 1992hrsw.conf...55D
  No abstract at ADS

Title: The distant future of solar activity: a case study of beta
    Hydri (abstract)
Authors: Dravins, D.; Linde, P.; Ayres, T. R.; Fredga, K.; Gahm, G.;
   Lindegren, L.; Linsky, J. L.; Monsignori-Fossi, B.; Nordlund, Å.;
   Simon, T.; Vandenberg, D.; Wallinder, F.
Bibcode: 1992sccw.conf..105D
Altcode:
  No abstract at ADS

Title: The rotationally broadened line profiles of Sirius.
Authors: Dravins, D.; Lindegren, L.; Torkelsson, U.
Bibcode: 1990A&A...237..137D
Altcode:
  Photospheric Fe I and Fe II absorption line profiles in Sirius
  are analyzed. The Fourier transforms of the line profiles reveal
  several sidelobes consistent with line broadening from rigid stellar
  rotation at V sin i = 15.3 + or - 0.3 km/s. The Fourier transforms
  are fitted, leading to deduced parameters of line profiles and stellar
  rotation. These profiles are remarkably similar to Gaussians with FWHM
  at about 8 km/s and resemble synthetic line profiles computed from
  hydrodynamic model atmospheres by Gigas (1989). The 'superposition' of
  neighboring absorption lines occasionally produces spectral features
  that are much narrower than the widths of individual rotationally
  broadened profiles. The widths of such 'subrotational' features may
  approach these of the 'intrinsic' line profiles, illustrating the need
  for very high spectral resolution to fully resolve the spectra also
  of rapidly rotating stars.

Title: Stellar activity cycles
Authors: Dravins, D.
Bibcode: 1990ESASP.310...61D
Altcode: 1990eaia.conf...61D
  No abstract at ADS

Title: Enhancing IUE spectrophotometry: a case study of Beta Hydri
Authors: Linde, P.; Dravins, D.
Bibcode: 1990ESASP.310..605L
Altcode: 1990eaia.conf..605L
  No abstract at ADS

Title: The distant future of solar activity - A case study of
    Beta Hydri
Authors: Dravins, D.; Linde, P.; Ayres, T. R.; Fredga, K.; Gahm, G.;
   Lindegren, L.; Linsky, J. L.; Monsignori-Fossi, B.; Nordlund, A.;
   Simon, T.; Vandenberg, D.; Wallinder, F.
Bibcode: 1990ESASP.310..323D
Altcode: 1990eaia.conf..323D
  No abstract at ADS

Title: The archival reprocessing of IUE data: I. An accurate
    registration technique for distorted images
Authors: de La Pena, M. D.; Shaw, R. A.; Linde, P.; Dravins, D.
Bibcode: 1990ESASP.310..617D
Altcode: 1990eaia.conf..617D
  No abstract at ADS

Title: Stellar granulation. IV. Line formation in inhomogeneous
    stellar photospheres.
Authors: Dravins, D.; Nordlund, A.
Bibcode: 1990A&A...228..184D
Altcode:
  Synthetic images of stellar granulation and photospheric Fe line
  profiles are computed in model atmospheres obtained from detailed
  numerical simulations of stellar surface convection. Models
  corresponding to Procyon (F5 IV-V), α Cen A (G2V), β Hyi (G2IV),
  and β Cen B (K1V) are studied (5200 ≤T<SUB>eff</SUB>≤6600 K). The
  broadening, wavelength shift and asymmetry of spatially and temporally
  resolved line profiles follows from radiative transfer in explicitly
  computed three- dimensional and time-variable velocity fields, and
  no adjustable - fitting parameters (such as e. g. "turbulence") are
  used. Synthetic white-light and monochromatic images illustrate the
  intensity contrast on stellar surfaces, its center-to-limb variation
  and the morphology of line formation. Spatially resolved and spatially
  averaged profiles illustrate line broadening through the Doppler
  effect in photospheric velocity fields. An increase in the velocity
  spread of spatially resolved lines near the stellar limbs reflects the
  larger amplitudes of horizontal velocities in line-forming layers. Time
  variability of spatially averaged line profiles and of their continuum
  flux levels reflects time evolution of convective patterns larger than
  individual granules. Spatially and temporally averaged data identify
  how different shapes, asymmetries and shifts among lines of different
  strength, excitation potential, ionization level, and wavelength region,
  map the detailed physical properties throughout the photo sphere. The
  properties of averaged profiles (in particular their asymmetries)
  are not at all typical for individual points on the stellar surface,
  but rather reflect the statistical distribution of photospheric
  inhomogeneities. Only very strong lines have sufficiently extended
  depths of formation for their asymmetry to be significantly influenced
  also by the depth-variation of photospheric flow velocities. Effects of
  the (non-LTE) radiative ionization of iron are not large but visible
  as a weakening of blueshifted Fe I line components above especially
  hot and bright granules. Convective blueshifts, originating from
  correlations between local brightness and local Doppler shift, vary
  between ∼=200 and 1000 ms<SUP>-1</SUP> at disk center in different
  stars. Since such correlations change throughout the atmosphere, already
  small differences in line formation conditions for lines of different
  strength or excitation potential may result in different asymmetries
  and wavelength shifts. For example, the lower surface gravity on the
  solar near-twin α Cen A permits larger velocity amplitudes in the
  high photosphere, causing noticeable differences to the Sun in the
  asymmetries of its stronger photospheric lines.

Title: Stellar granulation. V. Synthetic spectral lines in
    disk-integrated starlight.
Authors: Dravins, D.; Nordlund, A.
Bibcode: 1990A&A...228..203D
Altcode:
  Numerical simulations of stellar photo spheric structure have provided
  line profiles at different positions across stellar disks. Using
  these data, synthetic Fe line profiles in disk-integrated flux are
  computed (including their asymmetries and wavelength shifts) for
  models corresponding to Procyon (F 5 IV-V), α Cen A (G2V), β Hyi
  (G2IV) and α Cen B (K1V). The line profiles are computed without
  any adjustable physical parameters besides that of stellar rotation,
  and the model atmospheres contain no classical parameters such as
  "mixing-length" nor "turbulence". Since line strength, width, asymmetry,
  rotational broadening, and limb darkening change with disk position,
  the disk-integrated profiles reflect these properties in a complex
  manner. This intercoupling might allow determinations of not only
  stellar rotation, but also line profile variations across stellar disks,
  using observations of similar stars with different rotation. Grids of
  "observed" synthetic line profiles and bisectors illustrate effects
  of finite spectral resolution. Comparisons with observations show good
  agreement, and the stellar rotation can be independently determined from
  the symmetric line broadening, and from the bisector patterns. For the
  well observed stars Procyon and α Cen A, we estimate V sin i≃2.9
  and 1.8 km s<SUP>-1</SUP>, respectively. For the solar near-twin α
  Cen A, the profile and bisector fits are almost perfect, and permit
  the identification of subtle differences against the Sun, apparently
  reflecting changes in solar-type granulation during some billion years
  of stellar evolution. The bisector fit for Procyon is excellent, but
  some absorption is missing in the flanks of the intensity profiles
  outside about ±5 km s<SUP>-1</SUP>. This, and a similar effect in the
  subgiant β Hyi, is believed to be an artifact of the hydrodynamically
  anelastic atmospheric model, which excludes sound waves and absorption
  by features moving at near-sonic speeds. Different stars have different
  line asymmetries, and in each star there is a systematic dependence
  on line-strength. The excitation-potential and wavelength-region
  dependences are smaller. The convective blueshift of spectral lines
  ranges between ≃200 km s<SUP>-1</SUP> in K dwarfs to ≃1000 m
  s<SUP>-1</SUP> in F stars. Such effects may limit the accuracies
  possible in spectroscopic determinations of stellar radial velocities.

Title: Stellar granulation. VI. Four-component models and
    non-solar-type stars.
Authors: Dravins, Dainis
Bibcode: 1990A&A...228..218D
Altcode:
  A series of relatively simple empirical models of inhomogeneous stellar
  surfaces that allow granulation properties to be estimated also in
  stars for which detailed hydrodynamic models cannot yet be computed
  (e.g., the stars of spectral types A,F,G and K, reproducing observed
  line asymmetries) are presented. In these models, the stellar surface
  is divided into four components of different brightness and velocity,
  and the integrated stellar line profile is obtained as a summation
  of profiles from different components. By matching the synthetic and
  observed bisector patterns, estimates of the velocity and brightness
  amplitudes of stellar granulation can be obtained without a major
  computational effort.

Title: Stellar granulation. III. Hydrodynamic model atmospheres.
Authors: Nordlund, A.; Dravins, D.
Bibcode: 1990A&A...228..155N
Altcode:
  Detailed models for the three-dimensional, time-dependent and
  radiation-coupled hydrodynamics of solar granular convection have been
  adapted to stellar conditions, and extensive numerical simulations have
  been carried out to model four different stars in the vicinity of the
  sun in the H-R diagram. The results from the simulations, showing the
  three-dimensional structure and time evolution of temperature, velocity,
  and pressure features in stellar photospheres, are presented. They are
  then used as sets of temporally and spatially varying model atmospheres
  in which radiative transfer computations are made of the continuum and
  line radiation leaving the stars. Synthetic images show the optical
  appearance of stellar surface structure at different positions across
  stellar disks. Synthetic spectral line profiles are computed for
  different locations and times, and the buildup of average line profiles
  is examined for lines of different strength, excitation potential,
  ionization level, and wavelength region. The average line profiles
  are then used as an input to synthesize the disk-integrated flux of
  photospheric Fe lines for stars of different rotational velocities
  in order to predict observable spectral line shapes, asymmetries,
  and wavelength shifts.

Title: Stellar Granulation
Authors: Dravins, Dainis
Bibcode: 1990ASPC....9...27D
Altcode: 1990csss....6...27D
  Numerical simulations of the three-dimensional structure and time
  evolution of stellar surface convection are now feasible. Using the
  output from such simulations as sets of spatially and temporally
  varying model atmospheres, synthetic images of the stellar surface
  structure (granulation) as well as photospheric line profiles can
  be computed, and compared to observations. Such models are free
  from the classical ad hoc parameters of 'mixing-length', 'micro-' or
  'macro-turbulence'. Challenges for the future include detailed modeling
  of early-type, giant, and other nonsolar type stars. Signatures
  of stellar granulation are primarily observed as asymmetries and
  wavelength shifts in photospheric absorption lines. Observational
  challenges include identifying such asymmetries and shifts throughout
  the HR-diagram, monitoring lineshift variations during stellar activity
  cycles, and ultimately achieving spectroscopy across spatially resolved
  stellar disks.

Title: Observing, Modeling, and Understanding Stellar Granulation
Authors: Dravins, D.
Bibcode: 1990IAUS..138..397D
Altcode:
  No abstract at ADS

Title: The rotationally broadened line profiles of Sirius.
Authors: Dravins, D.; Lindegren, L.; Torkelsson, U.
Bibcode: 1990apsu.conf...19D
Altcode:
  No abstract at ADS

Title: Enhancing IUE spectrophotometry: a case study of Beta Hydri.
Authors: Linde, P.; Dravins, D.
Bibcode: 1990apsu.conf...45L
Altcode:
  No abstract at ADS

Title: The distant future of solar activity - a case study of
    Beta Hydri.
Authors: Dravins, D.; Linde, P.; Ayres, T. R.; Fredga, K.; Gahm, G.;
   Lindegren, L.; Linsky, J. L.; Monsignori-Fossi, B.; Nordlund, Å.;
   Simon, T.; Vandenberg, D.; Wallinder, F.
Bibcode: 1990apsu.conf...17D
Altcode:
  No abstract at ADS

Title: Enhancing IUE spectrophotometry: a case study of Beta Hydri.
Authors: Linde, P.; Dravins, D.
Bibcode: 1990nba..meet..181L
Altcode: 1990taco.conf..181L
  A technique for improved processing of data from the IUE satellite has
  been developed. A correlation scheme is used to directly measure the
  geometric displacement of the raw image, which enables the necessary
  geometric transformation to be carried out with subpixel accuracy. The
  resulting improvement in photometric calibration allows the subsequent
  data extraction to give spectra with significantly lower noise than with
  standard reduction methods. In an on-going search for chromospheric
  variability in the solar-type star β Hydri, nearly 100 IUE exposures
  have been reduced with the new method.

Title: Atmospheric intensity scintillation of stars on milli- and
    microsecond time scales.
Authors: Dravins, D.; Lindegren, L.; Mezey, E.
Bibcode: 1990apsu.conf...18D
Altcode:
  No abstract at ADS

Title: Stellar granulation.
Authors: Dravins, Dainis
Bibcode: 1990MmSAI..61..513D
Altcode:
  The spectroscopic features that can be interpreted as signatures
  of stellar granulation are described. Special attention is given to
  theoretical models of stellar granulation and synthetic photospheric
  line profiles in solar-type stars. Problems involved in observing
  subtle photospheric line asymmetries caused by stellar granulation
  are illustrated, and indirect methods that can be used for imaging
  stellar surfaces are discussed.

Title: A Cross Correlation Technique for Improved IUE Image
    Registration
Authors: de La Peña, M. D.; Shaw, R. A.; Linde, P.; Dravins, D.
Bibcode: 1989BAAS...21.1073D
Altcode:
  No abstract at ADS

Title: Absolute flux calibration of the H and K lines of CA II :
    chromospheric radiative losses in F and G-type stars.
Authors: Pasquini, L.; Pallavicini, R.; Dravins, D.
Bibcode: 1989A&A...213..261P
Altcode:
  Ca II H and K spectra of 81 (mainly Southern) F and G stars are
  analyzed using two different calibration methods. It is shown that, for
  spectra of sufficiently high resolution, and for stars of relatively
  low rotation rates, the calibrations of Linsky et al. (1979) and
  of Pasquini et al. (1988) give essentially the same results. These
  calibrations are used to derive absolute surface fluxes in the H and
  K lines of Ca II for 64 stars. It is shown that several late-F and
  early-G giants and supergiants have Ca II H and K fluxes in excess
  of about 10 to the 6th erg/sq cm s, much larger than those typically
  observed for normal giants of later spectral types.

Title: Stellar Granulation: Modeling of Stellar Surfaces and
    Photospheric Line Asymmetries
Authors: Dravins, D.
Bibcode: 1989ASIC..263..493D
Altcode: 1989ssg..conf..493D
  No abstract at ADS

Title: Challenges and Opportunities in Stellar Granulation
    Observations
Authors: Dravins, D.
Bibcode: 1989ASIC..263..153D
Altcode: 1989ssg..conf..153D
  No abstract at ADS

Title: The Lunde observatory method for IUE spectral image processing
Authors: Linde, Peter; Dravins, Dainis
Bibcode: 1988ESASP.281b.345L
Altcode: 1988uvai....2..345L; 1988IUE88...2..345L
  A method for IUE data processing and spectrum extraction is
  described. The geometric transformation of the raw image is made
  by identifying fixed patterns in the background outside spectral
  orders. By correlating these with patterns in the flat-field
  calibration exposures, geometric correction to within a fraction of
  one pixel appears possible. The photometric calibration thus avoids
  the pixel-to-pixel fixed-pattern noise ordinarily present, and the
  subsequent spectrum extraction may give spectra with significantly
  lower noise than ordinary reduction methods.

Title: Stellar Granulation and Photospheric Line Asymmetries
Authors: Dravins, D.
Bibcode: 1988IAUS..132..239D
Altcode:
  Numerical simulations of stellar surface convection in different stars
  have now been carried out, and such three-dimensional and time-dependent
  models predict the detailed stellar line profiles (including asymmetries
  and wavelength shifts), thus enabling a direct confrontation between
  observations and theory.

Title: The Lund Observatory method for IUE spectral image processing.
Authors: Linde, P.; Dravins, D.
Bibcode: 1988EIUEN..29....9L
Altcode:
  Since 1978 the authors have used the International Ultraviolet Explorer
  (IUE) satellite to monitor the solar-type star β Hydri (G2 IV) in order
  to detect long-term variations in chromospheric activity. The indicators
  they use are the Mg II h and k emission lines near 280 nm. β Hydri is
  estimated to be about twice as old as the sun. Current astrophysical
  theory predicts that this should result in a lowered overall magnetic-
  and chromospheric activity. This also implies that any variations of the
  Mg II emission line intensities are expected to be small. Preliminary
  data reductions, basically using the standard IUE software package,
  have shown this to be correct.

Title: The Lund Observatory method for IUE spectral image processing.
Authors: Linde, P.; Dravins, D.
Bibcode: 1988IUEEN..29....1L
Altcode:
  No abstract at ADS

Title: Stellar Granulation
Authors: Dravins, D.
Bibcode: 1987MitAG..70...64D
Altcode:
  No abstract at ADS

Title: Stellar granulation. I - The observability of stellar
    photospheric convection
Authors: Dravins, Dainis
Bibcode: 1987A&A...172..200D
Altcode:
  The application of astrophysical techniques, data analysis methods,
  and theoretical tools to investigate the stellar equivalent of solar
  granulation is considered. The aim is to study stellar photospheric
  convection patterns, the ensuing atmospheric inhomogeneities, and
  their effects on other observable parameters. Through experimental
  observations of sunlight, the ESO coude echelle spectrometer (in the
  special double-pass scanner mode) has been shown to be adequate for
  this task. The spectrometer, its performance, and its mode of operation
  are described. The selection of spectral lines is discussed for seven
  program stars (Sirius, Canopus, Procyon, Beta Hydri, Alpha Cen A,
  Alpha Cen B, and Arcturus). Examples are shown of observed stellar line
  profiles and the asymmetry of these line profiles is described by the
  computed line bisectors. The stellar bisector patterns for differently
  strong lines turn out to constitute a characteristic signature for
  each spectral type.

Title: Stellar granulation. II. Stellar photospheric line asymmetries.
Authors: Dravins, D.
Bibcode: 1987A&A...172..211D
Altcode:
  A search for a spectral signature of stellar granulation is made
  in seven stars of spectral types A, F, G, and K. Very high quality
  absorption line profiles have been obtained for Fe lines, using the
  ESO coude echelle spectrometer double-pass photoelectric scanner
  at a resolution λ/Δλ ≃ 200,000. Intrinsic line asymmetries are
  seen in all stars, with marked differences among different spectral
  types. The asymmetries are described by average bisectors for groups of
  similar spectral lines. A typical bisector amplitude is ≃ 300 m/s,
  a few percent of the line width. The characteristic solar granulation
  signature of progressively changing bisector slopes with changing
  line-strength is clearly indicated, in particular in the best-studied
  stars αCen A and Procyon. A survey of the Procyon spectral atlas is
  also made, and the asymmetries of 233 unblended Fe lines analyzed. This
  larger sample agrees very well with the photoelectric measurements
  and also shows additional trends, such as decreased bisector slope
  for lines at longer wavelengths.

Title: Photospheric Structure in Solar-Type Stars (Abstract)
Authors: Dravins, D.
Bibcode: 1987LNP...292...72D
Altcode: 1987ssp..conf...72D
  No abstract at ADS

Title: Stellar Granulation: Photospheric Line Asymmetries and
    Hydrodynamic Model Atmospheres
Authors: Dravins, D.; Nordlund, A.
Bibcode: 1986BAAS...18.1002D
Altcode:
  No abstract at ADS

Title: Solar Fe II line asymmetries and wavelength shifts.
Authors: Dravins, D.; Larsson, B.; Nordlund, A.
Bibcode: 1986A&A...158...83D
Altcode:
  Convective motions of solar granulation are manifest in the spatially
  unresolved spectrum as slight asymmetries and wavelength shifts of
  photospheric spectral lines. In a previous paper (Dravins et al.,
  1981) that dependence for Fe I lines with line strength, excitation
  potential and wavelength region was analyzed. This paper extends that
  work to Fe II lines, examining bisector shapes and wavelength shifts
  of "unblended" Fe II lines both at disk center and in integrated
  sunlight. Fe II lines form predominantly in the hotter and denser
  regions of the deep photosphere, and these different line formation
  conditions for Fe II manifest themselves in well-defined differences
  from Fe I: the average Fe II bisectors show a more articulated curvature
  and a larger convective blueshift. Synthetic spectral lines, computed
  from a three-dimensional time-dependent hydrodynamic simulation of
  solar photospheric convection confirm the observed behavior.

Title: Stellar Activity Cycle in Beta Hydri
Authors: Dravins, D.
Bibcode: 1986iue..prop.2585D
Altcode:
  No abstract at ADS

Title: Stellar activity cycles
Authors: Dravins, D.
Bibcode: 1986HiA.....7..393D
Altcode:
  Stellar activity cycles in the corona, chromosphere, photosphere,
  and deeper layers are examined. Observational problems related to the
  study of magnetic flux variations during solar cycle, of changes in
  the deeper layer and convective zone, and of ancient sun activity are
  described. Chromospheric activity cycles in ordinary stars, irradiance
  cycles in spotted stars, and flare frequency cycles in flare stars are
  considered. The need for the analysis of magnetic cycles in stellar
  activity and of cyclic activity in ordinary stars, and direct imaging
  of stellar surfaces is discussed.

Title: Stellat Activity Cycle in Beta Hydri
Authors: Dravins, D.
Bibcode: 1986iue..prop.2574D
Altcode:
  No abstract at ADS

Title: Stellar Activity Cycle in Beta Hydri
Authors: Dravins, D.
Bibcode: 1985iue..prop.2301D
Altcode:
  No abstract at ADS

Title: Stellar Lineshifts Induced by Photospheric Convection
Authors: Dravins, Dainis
Bibcode: 1985srv..conf..311D
Altcode: 1985IAUCo..88..311D; 1985srv..proc..311D; 1985LDP.....5..311D
  Effects of stellar atmospheres on measured radial velocities are
  examined. Surface convection ("stellar granulation") causes photospheric
  line asymmetries and wavelength shifts of ≅ 100 - 500 m/s. Cyclic
  changes in the convection patterns, such as observed during the solar
  11-year cycle, may mimic radial velocity variations of perhaps 30
  m/s. The study of stellar atmospheres would benefit from accurate
  (&lt; 100 m/s) differential radial velocity measurements among lines
  of different parameters (strength, excitation potential, wavelength
  region) in the same star.

Title: High resolution spectroscopy of alpha Centauri. I. Lithium
    depletion near one solar mass.
Authors: Soderblom, D. R.; Dravins, D.
Bibcode: 1984A&A...140..427S
Altcode:
  The lithium (Li) abundance of Alpha-Centauri A was measured and an
  upper limit was found for Li in Alpha Centauri B using the ESO Coude
  Echelle Spectrometer. The measurements were made in the 670.7 nm
  region in single-pass mode. The signal to noise ratio was not less
  than about 300 and was limited by the properties of the recorder. For
  Alpha-Centauri A the measured abundance was log N(Li) = 1.28, on a
  scale where log N(H) = 12.00. The upper limit for Li abundance in Alpha
  Centauri B was 0.7. It is shown that these abundances are consistent
  with the probable evolutionary age of the stars, given a mass of 1.1
  solar mass for Alpha Centauri A. The lithium depletion e-folding time
  for that mass is therefore about 1.4 Gyr, compared to 1.1 Gyr at 1.0
  solar mass. It is shown that the accuracy of estimates of the ages of
  individual stars based on Li abundances is limited when the masses are
  not precisely known. The age-related properties of solar-type stars
  that depend on Li abundances are discussed.

Title: Solar Fe II Line Asymmetries and Wavelength Shifts
Authors: Dravins, D.; Larsson, Birgitta
Bibcode: 1984ssdp.conf..306D
Altcode:
  Asymmetries are studied for 32 apparently unblended Fe II photospheric
  absorption lines in the solar disk center spectrum, and in the spectrum
  of integrated sunlight. Average bisectors have been computed for groups
  of similar lines, and the bisector variation is shown as function
  of line-strength and of excitation potential. The same trends as
  previously known from Fe I are present, although Fe II line shapes
  show subtle differences.

Title: Observing Stellar Granulation (Keynote)
Authors: Dravins, D.; Lind, J.
Bibcode: 1984ssdp.conf..414D
Altcode:
  Granulation-induced photospheric spectrum line asymmetries can be
  detected with high-resolution stellar spectrometers. Such stellar line
  asymmetries are well respresented by bisectors which show changing
  shapes for lines of different strengths. The solar near-twin α Cen A
  shows a bisector pattern very similar to that of the Sun. F- and K-type
  main-sequence stars have line asymmetries reminiscent of solar ones,
  but very different from those of F- and K-type giants. Stellar bisector
  patterns are presented from very high-resolution (λ/Δλ ≅ 200,000)
  observations made with the ESO double-pass coudé echelle spectrometer,
  and the observability of stellar bisectors also at moderate resolutions
  (≅ 100,000) is shown.

Title: Stellar granulation: evidence for stellar surface convection
    from photospheric line asymmetries.
Authors: Dravins, D.; Lind, J.
Bibcode: 1983PASP...95R.588D
Altcode:
  No abstract at ADS

Title: Stellar Granulation and the Structure of Stellar Surfaces
Authors: Dravins, D.
Bibcode: 1983Msngr..32...15D
Altcode:
  Convection in Stars Stellar convection is a central but poorly
  understood parameter In the construction of stellar models and
  the determination of stellar ages, influencing both the energy
  transport through the atmosPh.ere and the replenishment 01 nuclear
  fuels in the core. The motlons in stellar convection zones probably
  supply the energy for generating magnetic fields, heating stellar
  chromospheres and coronae, driving stellar winds, and for many other
  nonthermal phenomena. The inhomogeneous structure of velocity fields
  on stellar surfaces complicates the accurate determination of stellar
  radial velocities. Further, the temperature inhomogeneities on stellar
  surfaces induce molecular abundance inhomogeneities and entangle the
  accurate determination of chemical abundances.

Title: High Resolution Spectroscopy - the Need for Larger Telescopes
Authors: Dravins, D.
Bibcode: 1983ESOC...17..107D
Altcode: 1983vlt..work..107D
  No abstract at ADS

Title: Solar Activity 5 Billion Years in the Future - A Case Study
    of Beta Hydri
Authors: Dravins, D.; Linde, P.; Fredga, K.; Gahm, G.
Bibcode: 1983BAAS...15..698D
Altcode:
  No abstract at ADS

Title: Spectrograph Instrumental Profiles - Dependence on Dispersion
Authors: Andersen, J.; Dravins, D.
Bibcode: 1982PASP...94..390A
Altcode:
  Spectrograph instrumental profiles (including stray light far away
  from the central peak) have been measured in blue and red light for
  the three cameras in the coudé spectrograph of the 1.52-m telescope
  at Observatoire de Haute-Provence. The different dispersions 0.7,
  1.2, and 2.0 nm mm<SUP>-1</SUP> are obtained using the same ruled
  diffraction grating. On a linear distance scale in the focal plane
  the profiles are rather similar down to a 10<SUP>-3</SUP> intensity
  level, but on a wavelength scale the profiles improve with increasing
  dispersion, indicating the presence of a stray light component other
  than that caused by diffraction by grating irregularities. The effects
  of these instrumental profiles on observed spectra are illustrated by
  numerical convolutions with the solar spectrum.

Title: Convection in stellar atmospheres.
Authors: Dravins, D.; Lind, J.
Bibcode: 1982ROLun..18..109D
Altcode:
  No abstract at ADS

Title: Measurements of Photon Statistics with Nanosecond Resolution
Authors: Dravins, D.
Bibcode: 1982ASSL...92..229D
Altcode: 1982IAUCo..67..229D; 1982ialo.coll..229D
  No abstract at ADS

Title: Photospheric spectrum line asymmetries and wavelength shifts
Authors: Dravins, D.
Bibcode: 1982ARA&A..20...61D
Altcode:
  Results of studies on the asymmetries of spectral lines that have
  hitherto been regarded as symmetric are discussed. The discrepancy
  between solar and laboratory wavelengths is summarized, including
  the limb effect. Solar line profiles have been accurately measured,
  revealing intrinsic asymmetries in the lines. The causes of asymmetries
  and shifts can be traced back to photospheric inhomogeneities, so that
  high spatial resolution images and spectra of the solar granulation are
  needed to understand their origins. Recent theoretical developments in
  time-dependent and hydrodynamic solar and stellar model atmospheres
  incorporating convection permit predictions and interpretations of
  observed asymmetries and shifts. The asymmetries are also visible in
  integrated sunlight and the corresponding phenomena have been seen
  for a few bright stars.

Title: CA II and K chromospheric emission in F-and G-type stars.
Authors: Dravins, D.
Bibcode: 1981A&A....98..367D
Altcode:
  A survey of representative Ca II H and K line profiles (the most
  pronounced chromospheric indicators observable from the ground) is
  presented to illustrate the chromospheric emission of different types
  of F and G stars. Of the 90 stars observed, a typical one is selected
  for each spectral type, leaving a sample of 47. The spectral types are
  taken from Jaschek (1978), except when superseded by Keenan and Pitts
  (1980). For BS 3591 the Bright Star Catalog classification of F 8
  III is retained, and data for the sun (G 2 V) refer to observations
  of skylight, which is almost equal to integrated sunlight. General
  trends in the changing appearance of chromospheric emission, as well
  as the physical scatter of chromospheric activity levels among stars
  of similar photospheric properties, are presented. It is shown that
  the sun's level of chromospheric activity does not deviate much from
  what is typical for field stars of a similar spectral class.

Title: Nanosecond Resolution Observations: Quantum-Optical
    Spectroscopy and Intensity Interferometry
Authors: Dravins, D.
Bibcode: 1981siwn.conf..253D
Altcode:
  No abstract at ADS

Title: Search for chromospheres in A-type stars.
Authors: Dravins, D.
Bibcode: 1981A&A....96...64D
Altcode:
  A search for chromospheric emission in the Ca II H and K lines was
  made for eight main-sequence A-stars in the young clusters C 0838-528
  (IC 2391) and in the Hyades, where (at least later-type) stars have
  generally enhanced chromospheric activity, making possible emission
  easier to detect. No evidence for emission was found in these stars
  and nor in Sirius (A 1 V).

Title: Solar granulation - Influence of convection on spectral line
    asymmetries and wavelength shifts
Authors: Dravins, D.; Lindegren, L.; Nordlund, A.
Bibcode: 1981A&A....96..345D
Altcode:
  The observed shapes and shifts of 311 Fe I lines in the spectrum of
  solar disk center and also of integrated sunlight are investigated. Line
  shapes are described using bisectors, and the dependence of
  these on line strength, excitation potential, and wavelength
  region is analyzed. A theoretical model atmosphere incorporating
  radiation-coupled, time-dependent hydrodymamics of solar convection
  is used to compute synthetic photospheric spectral lines. These lines
  exhibit asymmetries and wavelength shifts, and the observed bisector
  behavior can be closely reproduced. The detailed properties of, for
  example, convective motions and changing granulation constrast with
  wavelength manifest themselves in the detailed bisector shapes. It is
  confirmed that convection is the principal cause of solar line shifts,
  and errors in other suggested explanations are pointed out. It is
  concluded that the study of line shapes and shifts is a powerful tool
  for the analysis of solar photospheric convection.

Title: Possible applications of long-baseline intensity
    interferometry.
Authors: Dravins, D.
Bibcode: 1981siha.conf..295D
Altcode:
  Atmospheric phase distortions presently limit ground-based optical
  phase interferometers to baselines of the order of 100 m. Intensity
  interferometry, however, avoids both atmospheric and instrumental
  phase distortion problems and permits the operation of optical
  interferometers with baselines of more than 10 km between existing large
  telescopes. Such baselines may make feasible the search for stellar
  surface inhomogeneities, and although only very bright objects could be
  observed, the angular resolution of about 0.000001 arcsec obtained would
  permit the study of fine structure on the surfaces of nearby stars.

Title: Photometric Properties of the IUE Flat-Field Calibration
    Exposures
Authors: Dravins, D.; Linde, P.
Bibcode: 1980idr..conf...85D
Altcode:
  No abstract at ADS

Title: Methods for accurate photographic stellar spectrophotometry
    using the solar spectrum as calibration
Authors: Lind, J.; Dravins, D.
Bibcode: 1980A&A....90..151L
Altcode:
  Methods for photographic spectrophotometry using single-pass
  spectrographs are developed with the purpose of obtaining stellar
  spectra of sufficiently high quality to allow detailed spectral line
  studies over extended wavelength regions. The spectrograph instrumental
  profile and photographic development effects are investigated, and
  the corresponding MTFs are determined by measuring the modulation
  experienced by a calibration spectrum of skylight and moonlight
  which is exposed side by side with the stellar spectrum on each
  plate. Either of these calibration spectra is very similar to the
  accurately known spectrum of integrated sunlight, whose modulation in
  the observing/recording/measuring process is then determined.

Title: Search for Spectral Line Polarization in the Solar Vacuum
    Ultraviolet
Authors: Stenflo, J. O.; Dravins, D.; Wihlborg, N.; Bruns, A.;
   Prokofev, V. K.; Zhitnik, I. A.; Biverot, H.; Stenmark, L.
Bibcode: 1980SoPh...66...13S
Altcode:
  An instrument designed to record polarization in the region 120-150 nm
  of the solar spectrum was launched on the satellite Intercosmos-16,
  July 27, 1976. The aim was to search for resonance-line polarization
  that is caused by coherent scattering. Oblique reflections at gold-
  and aluminium-coated mirrors in the instrument were used to analyze
  the polarization. The average polarization of the Lα solar limb was
  found to be less than 1%. It is indicated how future improved VUV
  polarization measurements may be a diagnostic tool for chromospheric
  and coronal magnetic fields and for the three-dimensional geometry of
  the emitting structures.

Title: Observed Solar Spectral Line Asymmetries and Wavelength Shifts
    due to Convection
Authors: Dravins, D.
Bibcode: 1980LNP...114...51D
Altcode: 1980IAUCo..51...51D; 1980sttu.coll...51D
  No abstract at ADS

Title: Comments on solar chromospheric activity compared to that
    of other stars (These comments were intended to be presented during
    the discussion but it was not possible for shortage of time.)
Authors: Dravins, D.
Bibcode: 1980fsoo.conf..266D
Altcode:
  No abstract at ADS

Title: The far-UV spectrum of the T Tauri star RU Lupi.
Authors: Gahm, G. F.; Fredga, K.; Liseau, R.; Dravins, D.
Bibcode: 1979A&A....73L...4G
Altcode:
  The spectrum of the T Tauri star RU Lupi from 1150 to 3100 A has
  been observed from the IUE satellite. It is rich in emission lines,
  seen superimposed on a background continuum and traceable from
  Ly-alpha to 3100 A. The region from 2000 to 3100 A is dominated by
  metal line emission of the same nature as previously observed in
  the optical region. The resonance lines of Mg II at 2795 and 2780 A
  are exceedingly strong. In the region from 1150 to 2000 A the most
  conspicuous features are the very strong emission lines of C IV,
  Si IV and Si III, indicating that regions of very high temperature
  (50,000 to 100,000 K) exist around the star.

Title: Comments on solar chromospheric activity compared to that of
    other stars.
Authors: Dravins, D.
Bibcode: 1979MmArc.106..266D
Altcode:
  No abstract at ADS

Title: Holography at the telescope - an interferometric method for
    recording stellar spectra in thick photographic emulsions.
Authors: Lindegren, L.; Dravins, D.
Bibcode: 1978A&A....67..241L
Altcode:
  Low-resolution spectra (resolving power of no more than about 100) are
  recorded without any dispersive optics by direct focal-plane Lippmann
  photography using thick holographic emulsions. These record the Fourier
  transforms of the spectra, enabling spectrum reconstruction by reflected
  light and analysis with a microspectrophotometer. Since the spectral
  information is stored inside the emulsion and perpendicular to the
  holographic plate surface, problems with overlapping spectrograms in
  dense star fields are eliminated. Spectral resolution is set by emulsion
  thickness and is independent of seeing and telescope guiding. The
  holographic storage format appears suitable for automated spectral
  searches, and the future feasibility of a holographic spectral
  sky survey with Schmidt telescopes is suggested. Theoretical and
  experimental work is presented, and practical and theoretical
  limitations discussed.

Title: High-dispersion astronomical spectroscopy with holographic
    and rules diffraction gratings.
Authors: Dravins, D.
Bibcode: 1978ApOpt..17..404D
Altcode:
  Holographic gratings cause much less stray light and spectral
  degradation than classically ruled gratings. Their high groove
  densities enable high dispersion in first diffraction order and a
  high spectrograph throughput comparable to the best echelles. Their
  lower reflective efficiency is compensated by the avoidance of
  cross dispersers, enabling efficient high-fidelity spectroscopy with
  single-pass spectrographs. Instrumental profiles of the ESO coude
  spectrograph with large holographic and ruled gratings have been
  studied in detail, and their effects on astronomical spectra are
  discussed and compared to those of other instruments.

Title: Holographic gratings for astronomical spectroscopy.
Authors: Dravins, D.
Bibcode: 1978sss..meet...E5D
Altcode:
  No abstract at ADS

Title: Diffraction Gratings - Holographic and Ruled
Authors: Dravins, D.
Bibcode: 1978hrs..conf..221D
Altcode:
  No abstract at ADS

Title: Comments on solar chromospheric activity compared to that of
    other stars
Authors: Dravins, D.
Bibcode: 1978fsoo.conf..266D
Altcode:
  No abstract at ADS

Title: Beryllium in Alpha Centauri A and constraints on beryllium
    formation.
Authors: Dravins, D.; Hultqvist, L.
Bibcode: 1977A&A....55..463D
Altcode:
  The equivalent width of the Be II 313.1-nm line in Alpha Cen A (G2 V)
  is determined to be 1.25 times the solar value, leading to a Be/H
  abundance ratio of 2.5 by 10 to the -11th power. The age of Alpha
  Cen A is estimated to 8 billion years. This, together with observed
  Be in the old stars Delta Eri (K0 IV) and Mu Her A (G5 IV), indicates
  that beryllium existed in significant amounts relatively early in the
  history of the Galaxy.

Title: Observations of resonance-line polarization in the solar EUV.
Authors: Stenflo, J. O.; Dravins, D.; Öhman, Y.; Wihlborg, N.;
   Bruns, A.; Prokof'ev, V. K.; Severnyj, A.; Severny, A.; Zhitnik,
   I. A.; Biverot, H.; Stenmark, L.
Bibcode: 1977ROLun..12..147S
Altcode:
  No abstract at ADS

Title: Chromospheric activity and atmospheric dynamics in Rho Puppis
    and other Delta-Scuti stars.
Authors: Dravins, D.; Lind, J.; Sarg, K.
Bibcode: 1977A&A....54..381D
Altcode:
  Summary. The Scuti pulsating variable Pup (P = 0d 14) is studied using
  simultaneous spectrographic and photometric observations. A transient
  Ca ii K chromospheric emission is seen at a phase near maximum outward
  acceleration, shock waves are identified from radial velocity behavior
  at different atmospheric levels, a secondary minimum is seen in radial
  velocity and phase- shifts are detected between light-curves for
  different wavelengths. The latter permit a stellar radius determination
  through a phase-matching method. In addition, four other a Scuti
  stars have been studied for K emission. Key words: variable stars -
  stellar chromospheres shock waves - stellar radii uvby photometry

Title: Spectrograph Instrumental Profiles--A Comparison between
    Holographic and Ruled Gratings.
Authors: Dravins, D.
Bibcode: 1976BAAS....8..517D
Altcode:
  No abstract at ADS

Title: Chromospheric Activity in f- and G-Stars
Authors: Dravins, D.
Bibcode: 1976IAUS...71..469D
Altcode:
  No abstract at ADS

Title: Observation of convection in stellar atmospheres
Authors: Dravins, D.
Bibcode: 1976pmas.conf..459D
Altcode:
  No abstract at ADS

Title: a Self-Scanned Silicon Diode Array for Astronomical Photometry
Authors: Dravins, D.
Bibcode: 1975ASSL...54...97D
Altcode: 1975ipta.proc...97D
  No abstract at ADS

Title: Physical limits to attainable accuracies in stellar radial
    velocities.
Authors: Dravins, D.
Bibcode: 1975A&A....43...45D
Altcode:
  It is shown that true stellar radial velocities cannot be obtained
  from spectral lines with a precision of better than 0.5 km/sec unless
  detailed knowledge of small-scale inhomogeneities in the line-formation
  region is available. Two models are calculated which demonstrate
  that convection-cell velocity patterns in particular cause line
  asymmetries and average wavelength shifts that depend critically on
  many unknown parameters and are likely to vary from star to star. It
  is suggested that more accurate radial velocities might be obtained
  from strong lines that form in layers above both the convection zone
  and the region of convective overshoot. The Na I D(1) line at 5896 A
  is recommended as the best line to use for this purpose, although it
  may be contaminated by chromospheric emission as well as circumstellar
  and interstellar absorption.

Title: Height Dependence of Horizontal Velocities in the Photosphere
Authors: Dravins, D.
Bibcode: 1975BAAS....7..363D
Altcode:
  No abstract at ADS

Title: Horizontal Velocities in the Solar Photosphere
Authors: Dravins, D.
Bibcode: 1975SoPh...40...53D
Altcode:
  Horizontal macroscopic velocities V<SUB>hor</SUB> in the photosphere
  are studied. High-resolution spectrograms of quiet regions are
  analyzed for center-limb variation of rms Doppler shifts. The data
  are treated to assure that the observed velocities refer to constant
  size volumes on the Sun (800 × × 3000 × 250 km), independent of
  μ. Using known height variation of vertical velocities and calculated
  line formation heights, the height dependence of «V<SUB>hor</SUB>»
  is obtained. From a value around 450 m s<SUP>−1</SUP> it decreases
  rapidly with increasing height. To study also small-scale velocities,
  the time evolution of subarcsecond size elements in the photospheric
  network (solar filigree) is studied on filtergrams. It is concluded
  that they show proper motions implying «V<SUB>hor</SUB>» about 1
  km s<SUP>−1</SUP>.

Title: Instrument profiles in stellar spectrography.
Authors: Dravins, D.
Bibcode: 1975ROLun...5..241D
Altcode:
  No abstract at ADS

Title: Measurements in stellar spectra: Lectures at the Lund
    Observatory Nordic Summer School 1975
Authors: Ardeberg, A.; Larsson-Leander, G.; Lynga, G.; Dravins, D.;
   Andersen, J.
Bibcode: 1975STIN...7634081A
Altcode:
  Transcripts of five lecture series given during the 1975 summer
  are given. These deal with the following subjects: measurement of
  stellar continuous spectra, measurement of spectral lines, automatic
  evaluation methods, instrument profiles in stellar spectrographs,
  and modern spectrograph design.

Title: Convection in the photosphere of Arcturus
Authors: Dravins, D.
Bibcode: 1974A&A....36..143D
Altcode:
  Convective motions in stellar atmospheres involve hot gases that
  rise, cool off and then sink back. High-excitation spectral lines are
  preferentially formed in the hot, rising and thus locally blue-shifted
  elements while low-excitation lines are preferentially formed in
  the cooler, sinking and red-shifted elements. By comparing accurate
  wavelengths for spectral lines in Arcturus with laboratory values, a
  relation is found, such that high-excitation lines are systematically
  blue-shifted relative to low-excitation lines. This relation is very
  similar to the one previously known for the sun and is interpreted as
  the existence of convection cells, similar to the solar granulation,
  in the photosphere of Arcturus.

Title: Magnetic Field and Electric Current Structure in the
    Chromosphere
Authors: Dravins, D.
Bibcode: 1974SoPh...37..323D
Altcode:
  Three dimensional vector magnetic field structure throughout the
  chromosphere above an active region is deduced by combining high
  resolution Hα filtergrams with a simultaneous digital magnetogram. An
  analog model of the field is made with 400 metal wires representing
  fieldlines which are assumed to outline the Hα structure. The
  height extent of the field is determined from vertical field gradient
  observations around sunspots, from observed fibril heights and from an
  assumption that the sources of the field should be largely local. After
  digitization the magnetic field H matrix is retrieved. Electric current
  densities j are computed from j=curl H. The currents (typically 10 mA
  m<SUP>−2</SUP>) flow in patterns not similar to observed features
  and not parallel to magnetic fields. Lorentz forces are computed
  from {ie0323-01}. The force structures correspond to observed
  solar features and a series of observed dynamics may be expected:
  downward motion in bipolar areas in lower chromosphere, an outflow
  of the outer chromosphere into the corona with radially outward flow
  above bipolar plage regions (where coronal streamers are observed)
  and motions of arch filament systems. Observed current structure and
  magnitude agree well with previous vector magnetograph observations
  but disagree with theoretical current-free or force-free concepts. A
  dynamic chromosphere with electromagnetic forces in action is thus
  inferred from observations.

Title: Evolution of Structures in the Bright Hα Network
Authors: Dravins, D.
Bibcode: 1974IAUS...56..257D
Altcode:
  No abstract at ADS

Title: A Possible Solar Electrograph
Authors: Dravins, Dainis
Bibcode: 1973ApL....13..243D
Altcode:
  No abstract at ADS

Title: Solen sedd i väteljus.
Authors: Dravins, D.
Bibcode: 1973ATi.....6..100D
Altcode:
  No abstract at ADS

Title: Magnetic Fields, Electric Currents and Lorentz Forces in
    the Chromosphere.
Authors: Dravins, D.
Bibcode: 1972BAAS....4Q.309D
Altcode:
  No abstract at ADS

Title: Ballongastronomi.
Authors: Dravins, D.
Bibcode: 1970ATi.....3...53D
Altcode:
  No abstract at ADS

