Author name code: battacharyya
ADS astronomy entries on 2022-09-14
author:"Bhattacharyya, J" 
------------------------------------------------------------------------  

Title: de Sitterization via Kerr-Schild
Authors: Sharma, Aditya; Banerjee, Kinjal; Bhattacharyya, Jishnu
Bibcode: 2022arXiv220504773S
Altcode:
  Spatially homogeneous cosmological spacetimes, evolving in the
  presence of a positive cosmological constant and matter satisfying
  some reasonable energy conditions, typically approach the de Sitter
  geometry asymptotically (at least locally). In this work, we propose an
  alternate way to characterize this phenomena. We focus on a subset of
  such models admitting a generalized Kerr-Schild representation. We argue
  that the functions which define such a representation can be chosen,
  such that, their asymptotic behavior make the evolution towards the
  de Sitter spacetime manifest through the representation. We verify
  our claim for the Kantowski-Sachs family of cosmological spacetimes.

Title: Dynamical obstruction to perpetual motion from
    Lorentz-violating black holes
Authors: Benkel, Robert; Bhattacharyya, Jishnu; Louko, Jorma;
   Mattingly, David; Sotiriou, Thomas P.
Bibcode: 2018PhRvD..98b4034B
Altcode: 2018arXiv180301624B
  Black holes in Lorentz-violating theories have been claimed to
  violate the second law of thermodynamics by perpetual motion energy
  extraction. We revisit this question for a Penrose splitting process
  in a spherically symmetric setting with two species of particles
  that move on radial geodesics that extend to infinity. We show that
  energy extraction by this process cannot happen in any theory in which
  gravity is attractive, in the sense of a geometric inequality that we
  describe. This inequality is satisfied by all known Einstein-æther
  and Hořava black hole solutions.

Title: Revisiting the cuscuton as a Lorentz-violating gravity theory
Authors: Bhattacharyya, Jishnu; Coates, Andrew; Colombo, Mattia;
   Gümrükçüoǧlu, A. Emir; Sotiriou, Thomas P.
Bibcode: 2018PhRvD..97f4020B
Altcode: 2016arXiv161201824B
  The cuscuton is a scalar field with infinite speed of propagation. It
  was introduced in the context of cosmology but it has also been claimed
  to resemble Hořava gravity in a certain limit. Here we revisit the
  cuscuton theory as a Lorentz-violating gravity theory. We clarify its
  relation with Hořava gravity and Einstein-æther theory, analyze its
  causal structure, and consider its initial value formulation. Finally,
  we discuss to which extent the cuscuton theory can be used as a proxy
  for Hořava gravity in the context of gravitational collapse and
  formation of universal horizons.

Title: Simulating Coronal Loop Implosion and Compressible Wave Modes
    in a Flare Hit Active Region
Authors: Sarkar, Aveek; Vaidya, Bhargav; Hazra, Soumitra;
   Bhattacharyya, Jishnu
Bibcode: 2017ApJ...851..120S
Altcode: 2017arXiv171105273S
  There is considerable observational evidence of implosion of magnetic
  loop systems inside solar coronal active regions following high-energy
  events like solar flares. In this work, we propose that such collapse
  can be modeled in three dimensions quite accurately within the framework
  of ideal magnetohydrodynamics. We furthermore argue that the dynamics
  of loop implosion is only sensitive to the transmitted disturbance
  of one or more of the system variables, e.g., velocity generated at
  the event site. This indicates that to understand loop implosion,
  it is sensible to leave the event site out of the simulated active
  region. Toward our goal, a velocity pulse is introduced to model the
  transmitted disturbance generated at the event site. Magnetic field
  lines inside our simulated active region are traced in real time,
  and it is demonstrated that the subsequent dynamics of the simulated
  loops closely resemble observed imploding loops. Our work highlights
  the role of plasma β in regards to the rigidity of the loop systems
  and how that might affect the imploding loops’ dynamics. Compressible
  magnetohydrodynamic modes such as kink and sausage are also shown to
  be generated during such processes, in accordance with observations.

Title: Causality and black holes in spacetimes with a preferred
    foliation
Authors: Bhattacharyya, Jishnu; Colombo, Mattia; Sotiriou, Thomas P.
Bibcode: 2016CQGra..33w5003B
Altcode: 2015arXiv150901558B
  We develop a framework that facilitates the study of the causal
  structure of spacetimes with a causally preferred foliation. Such
  spacetimes may arise as solutions of Lorentz-violating theories,
  e.g. Hořava gravity. Our framework allows us to rigorously define
  concepts such as black/white holes and to formalize the notion of a
  ‘universal horizon’, that has been previously introduced in the
  simpler setting of static and spherically symmetric geometries. We
  also touch upon the issue of development and prove that universal
  horizons are Cauchy horizons when evolution depends on boundary data
  or asymptotic conditions. We establish a local characterisation of
  universal horizons in stationary configurations. Finally, under the
  additional assumption of axisymmetry, we examine under which conditions
  these horizons are cloaked by Killing horizons, which can act like
  usual event horizons for low-energy excitations.

Title: Asymptotically Lifshitz spacetimes with universal horizons in
    (1 +2 ) dimensions
Authors: Basu, Sayandeb; Bhattacharyya, Jishnu; Mattingly, David;
   Roberson, Matthew
Bibcode: 2016PhRvD..93f4072B
Altcode: 2016arXiv160103274B
  Hořava gravity theory possesses global Lifshitz space as a solution
  and has been conjectured to provide a natural framework for Lifshitz
  holography. We derive the conditions on the two-derivative Hořava
  gravity Lagrangian that are necessary for static, asymptotically
  Lifshitz spacetimes with flat transverse dimensions to contain a
  universal horizon, which plays a similar thermodynamic role as the
  Killing horizon in general relativity. Specializing to z =2 in 1 +2
  dimensions, we then numerically construct such regular solutions over
  the whole spacetime. We calculate the mass for these solutions and
  show that, unlike the asymptotically anti-de Sitter case, the first
  law applied to the universal horizon is straightforwardly compatible
  with a thermodynamic interpretation.

Title: Evolution and spherical collapse in Einstein-Æther theory
    and Hořava gravity
Authors: Bhattacharyya, Jishnu; Coates, Andrew; Colombo, Mattia;
   Sotiriou, Thomas P.
Bibcode: 2016PhRvD..93f4056B
Altcode: 2015arXiv151204899B
  We compare the initial value formulation of the low-energy limit of
  (nonprojectable) Hořava gravity to that of Einstein-æther theory when
  the æther is assumed to be hypersurface orthogonal at the level of the
  field equations. This comparison clearly highlights a crucial difference
  in the causal structure of the two theories at the nonperturbative
  level: in Hořava gravity evolution equations include an elliptic
  equation that is not a constraint relating initial data but needs to
  be imposed on each slice of the foliation. This feature is absent in
  Einstein-æther theory. We discuss its physical significance in Hořava
  gravity. We also focus on spherical symmetry, and we revisit existing
  collapse simulations in Einstein-æther theory. We argue that they
  have likely already uncovered the dynamical formation of a universal
  horizon and that they can act as evidence that this horizon is indeed
  a Cauchy horizon in Hořava gravity.

Title: Universal horizons in maximally symmetric spaces
Authors: Bhattacharyya, Jishnu; Mattingly, David
Bibcode: 2014IJMPD..2343005B
Altcode: 2014arXiv1408.6479B
  Universal horizons in Hořava-Lifshitz gravity and Einstein-æther
  theory are the equivalent of causal horizons in general relativity
  and appear to have many of the same properties, including a first
  law of horizon thermodynamics and thermal radiation. Since universal
  horizons are infrared (IR) solutions of a putative power counting
  renormalizable quantum gravitational theory, fully understanding
  their thermodynamics will shed light on the interplay between black
  hole thermodynamics and quantum gravity. In this paper, we provide
  a complete classification, including asymptotic charges, of all
  four-dimensional static and spherically symmetric universal horizon
  solutions with maximally symmetric asymptotics — the equivalents of
  the Schwarzschild, Schwarzschild-de Sitter or Schwarzschild-anti-de
  Sitter spacetimes. Additionally, we derive the associated first laws for
  the universal horizon solutions. Finally, we prove that independent of
  asymptotic boundary conditions, any spherically symmetric solution in
  Hořava-Lifshitz gravity with a universal horizon is also a solution
  of Einstein-æther theory, thereby broadening and complementing the
  known equivalence region of the solution spaces.

Title: Towards Thermodynamics of Universal Horizons in Einstein-æther
    Theory
Authors: Berglund, Per; Bhattacharyya, Jishnu; Mattingly, David
Bibcode: 2013PhRvL.110g1301B
Altcode: 2012arXiv1210.4940B
  Holography grew out of black hole thermodynamics, which relies on
  the causal structure and general covariance of general relativity. In
  Einstein-æther theory, a generally covariant theory with a dynamical
  timelike unit vector, every solution breaks local Lorentz invariance,
  thereby grossly modifying the causal structure of gravity. However,
  there are still absolute causal boundaries, called “universal
  horizons,” which are not Killing horizons yet obey a first law of
  black hole mechanics and must have an entropy if they do not violate
  a generalized second law. We couple a scalar field to the timelike
  vector and show via the tunneling approach that the universal horizon
  radiates as a blackbody at a fixed temperature, even if the scalar
  field equations also violate local Lorentz invariance. This suggests
  that the class of holographic theories may be much broader than
  currently assumed.

Title: Charged dilatonic AdS black branes in arbitrary dimensions
Authors: Berglund, Per; Bhattacharyya, Jishnu; Mattingly, David
Bibcode: 2012JHEP...08..042B
Altcode: 2011arXiv1107.3096B
  We study electromagnetically charged dilatonic black brane solutions
  in arbitrary dimensions with flat transverse spaces, that are
  asymptotically AdS. This class of solutions includes spacetimes which
  possess a bulk region where the metric is approximately invariant
  under Lifshitz scalings. Given fixed asymptotic boundary conditions,
  we analyze how the behavior of the bulk up to the horizon varies with
  the charges and derive the extremality conditions for these spacetimes.

Title: Mechanics of universal horizons
Authors: Berglund, Per; Bhattacharyya, Jishnu; Mattingly, David
Bibcode: 2012PhRvD..85l4019B
Altcode: 2012arXiv1202.4497B
  Modified gravity models such as Hořava-Lifshitz gravity or
  Einstein-æther theory violate local Lorentz invariance and therefore
  destroy the notion of a universal light cone. Despite this, in the
  infrared limit both models above possess static, spherically symmetric
  solutions with “universal horizons”—hypersurfaces that are
  causal boundaries between an interior region and asymptotic spatial
  infinity. In other words, there still exist black hole solutions. We
  construct a Smarr formula (the relationship between the total energy
  of the spacetime and the area of the horizon) for such a horizon in
  Einstein-æther theory. We further show that a slightly modified first
  law of black hole mechanics still holds with the relevant area now
  a cross-section of the universal horizon. We construct new analytic
  solutions for certain Einstein-æther Lagrangians and illustrate how our
  results work in these exact cases. Our results suggest that holography
  may be extended to these theories despite the very different causal
  structure as long as the universal horizon remains the unique causal
  boundary when matter fields are added.

Title: Infrasound from large surf
Authors: Garcés, M.; Aucan, J.; Fee, D.; Caron, P.; Merrifield, M.;
   Gibson, R.; Bhattacharyya, J.; Shah, S.
Bibcode: 2006GeoRL..33.5611G
Altcode:
  Simultaneous infrasonic, visual, and ocean-bottom pressure sensor
  observations of large swells on the island of Kauai and small to
  medium-sized surf on the island of Hawaii yielded a clear relationship
  between breaking wave height and low-frequency atmospheric sound
  amplitudes in the 1-20 Hz frequency range. These experiments confirmed
  that infrasound can be generated by barreling waves as well as by
  waves crashing against rocky shorelines and exposed ledges. As will
  be demonstrated in a companion paper, breaking wave period may also
  be extracted from infrasound data. The results of these experiments
  demonstrate that low-frequency sound may be used for real-time estimates
  of the amplitude, period, and spatial distribution of surf in the
  littoral zone, with a potential application to the identification of
  breaking wave types.

Title: Different distribution functions of solar x-ray flares
Authors: Das, T. K.; de, B. K.; Bhattacharyya, J.
Bibcode: 2004BASI...32...15D
Altcode:
  No abstract at ADS

Title: Neutrino Oscillation as Coupled vibration
Authors: Bhattacharyya, Jyotisekhar; Biswas, Satyabrata
Bibcode: 2002gr.qc....11097B
Altcode:
  Neutrino oscillation is visualized as coupled vibrations. Unlike
  existing models describing neutrino oscillations, our model involving
  a single fundamental mass parameter $m$ and first discussed in the
  context of a possible boson oscillation demonstrates that for a self
  consistent theory there should be three types of bosons paired with
  maximal mixing. The argument is easily extended to neutrinos (fermions)
  with the exception that in the case of boson oscillation means periodic
  variation of particle number, whereas in the case of fermions the
  particle number does not change, only the mass oscillates. The
  fermionic vacuum is not really empty but filled with zero energy
  fermions. The oscillation length calculated perturbatively conforms to
  the experimental findings. Also there is no fermionic number violation
  in our model.

Title: Upper Mantle Shear and Compressional Velocity Structure of
the Central US Craton: Shear Wave Low-Velocity Zone and Anisotropy
Authors: Rodgers, Arthur; Bhattacharyya, Joydeep
Bibcode: 2001GeoRL..28..383R
Altcode:
  One-dimensional upper mantle velocity structure is estimated by modeling
  P, SV and SH body-waveforms sampling the central United States. The
  resulting model features a thick mantle lid with a positive velocity
  gradient. A significant shear wave low-velocity zone (6% velocity
  reduction) is required below the lid however the compressional
  velocities are not reduced. The paths studied lie along the fast axes
  of teleseismic shear wave splitting measurements and absolute plate
  motion. We observe splitting of upper mantle refracted shear-waves,
  with the transverse component slow relative to the radial component. In
  order to fit the shear wave arrivals and satisfy teleseismic shear-wave
  splitting observations we infer azimuthal anisotropy (maximum 1.6%)
  distributed throughout the mantle lid and low-velocity zone, with
  increasing anisotropy with depth.

Title: Studies on some aspects of solar X-ray flares.
Authors: Das, T. K.; de, B. K.; Bhattacharyya, J.
Bibcode: 1999InJPB..73..695D
Altcode:
  Studies have been made on the solar X-ray flares observed by GOES
  during the period July 1993 - June 1994, which encompasses the
  post-maximum phase of 22nd solar cycle. It has been examined that N-S
  asymmetry remains positive in respect of both latitudinal position
  and intensity of X-ray flares and increases with the increase of
  intensity. The E-W asymmetry is found to be zero, when longitudinal
  distribution is considered; but it remains positive up to a certain
  intensity value above which it becomes negative. The duration and
  rise time lie respectively in the ranges of values 5 - 15 min and 0 -
  5 min. The distribution of impulsiveness of X-ray flares follows an
  almost binomial distribution pattern peaking around 0.45.

Title: The Intermediate Polar PQ GEM -- Status of Wet Observations
    of 1996
Authors: Marar, T. M. K.; Seetha, S.; Ashoka, B. N.; Kasturirangan,
   K.; Mahra, H. S.; Bhattacharyya, J. C.; Leibowitz, E. M.; Hemar, S.;
   Mendelson, H.; Ibbetson, P. A.; O'Donoghue, D.; Buckley, D. A. H.;
   Breger, M.; Handler, G.; Sperl, M.; Serkowitsch, E.; Reegen, P.;
   Moskalik, P.; Zola, S.; Pajdosz, G.; Krzesinski, J.; Silvotti, R.;
   Vauclair, G.; Dolez, N.; Solheim, J. -E.; Pfeiffer, B.; Kepler, S. O.;
   Kanaan, A.; Provencal, J.; Kawaler, S. D.; O'Brien, M. S.; Nather,
   R. E.; Winget, D. E.; Kleinman, S.; Nitta, A.; Bradley, P. A.; Guzik,
   J. A.; Clemens, C.; Sullivan, D. J.; Jiang, X.
Bibcode: 1998BaltA...7..287M
Altcode: 1998OAst....7..287M
  A summary of the results on PQ Gem based on WET observations conducted
  in February 1996 is presented. The 13.9 min spin period of the white
  dwarf in the system and the orbital side-band at 14.5 min have been
  detected unambiguously. Searches for other periods in the system gave
  negative results.

Title: HiRES: the High-Resolution EUV Spectroheliometer
Authors: Timothy, J. Gethyn; Bergamini, Paolo; Bhattacharyya, Jagadish
   C.; Huber, Martin H.; Jain, Surendra K.; Naletto, Giampiero; Nicholls,
   Ralph W.; Nicolosi, Piergiorgio; Saxena, Ajay K.; Tondello, Giuseppe;
   Walker, Arthur B.
Bibcode: 1997SPIE.3114..450T
Altcode:
  The high-resolution EUV spectroheliometer (HiRES) is our first step
  towards the 0.1 arc sec angular resolution goal at EUV wavelengths. The
  HiRES instrument consists of a Gregory telescope with a 45-cm-diameter
  primary mirror, and an imaging EUV spectrometer, employing a
  single-reflection toric diffraction grating in a Rowland circle mounting
  and an imaging pulse-counting multi-anode microchannel array (MAMA)
  detector system. The MAMA detector covers the spectral range from 560
  to 631 angstrom with a spectral resolution of 70 mAngstrom. A Pt/Ne
  lamp impresses a wavelength calibration spectrum on the upper part
  of the detector while the solar spectrum is recorded simultaneously
  on the lower part. The times-of-arrival and addresses of the detected
  photons are transmitted directly to the ground to allow correction of
  the SPARCS pointing jitter. The HiRES spectrometer slit is pointed to a
  specific location using real-time control of the SPARCS, and SPARCS can
  be commanded to execute a linear (push broom) scan across the sun. Two
  EUV photodiodes are used to measure the absolute sola irradiances and
  the atmospheric extinction profiles in wavelength bands centered at
  304 angstrom and 584 angstrom respectively.

Title: My encounter with astronomy : early years
Authors: Bhattacharyya, J. C.
Bibcode: 1997BASI...25...19B
Altcode:
  No abstract at ADS

Title: My encounter with astronomy : later years
Authors: Bhattacharyya, J. C.
Bibcode: 1997BASI...25...29B
Altcode:
  No abstract at ADS

Title: Structures in Saturn's Magnetosphere
Authors: Bhattacharyya, J. C.
Bibcode: 1995JApAS..16..377B
Altcode:
  No abstract at ADS

Title: Detection of optical pulsations from RX J0558.0+5353.
Authors: Ashoka, B. N.; Marar, T. M. K.; Seetha, S.; Kasturirangan,
   K.; Bhattacharyya, J. C.
Bibcode: 1995A&A...297L..83A
Altcode:
  We report the detection of optical pulsations at a period of
  272.785+-0.003s from the newly discovered intermediate polar RX
  J0558.0+5353. This period nearly coincides with the X-ray period
  reported by Haberl et al. (1994). In the optical band the folded light
  curve of the star reveals a non-sinusoidal pulse with a pulsed fraction
  of 10.8%.

Title: A Personal Computer-Based Imaging Stokes Polarimeter for
    Solar Observations
Authors: Ananth, A. V.; Venkatakrishnan, P.; Narayanan, R. S.;
   Bhattacharyya, J. C.
Bibcode: 1994SoPh..151..231A
Altcode:
  For measurements of vector magnetic field over solar active regions,
  a Stokes polarimeter for studying the polarisation profiles on
  selected spectral lines is described. This paper gives details of
  the relevant CCD imaging system and the personal computer (PC)-based
  acquisition, together with the image analysis techniques necessary
  for the task. Field trials and tests of the system are also described.

Title: Report of IAU Commission 9: Instruments and techniques
    (Instruments et techniques).
Authors: Bhattacharyya, J. C.
Bibcode: 1994IAUTA..22...39B
Altcode:
  No abstract at ADS

Title: Inner Core Attenuation From Short-Period Pkp(Bc) Versus
    Pkp(Df) Waveforms
Authors: Bhattacharyya, Joydeep; Shearer, Peter; Masters, Guy
Bibcode: 1993GeoJI.114....1B
Altcode:
  No abstract at ADS

Title: The High Resolution Extreme-Ultraviolet Spectroheliometer
(HiRES) Experiment: Capabilities and Observing Goals
Authors: Berger, T. E.; Timothy, J. G.; Walker, A. B. C., Jr.; Jain,
   S. K.; Saxena, A. K.; Bhattacharyya, J. C.; Huber, M. C. E.; Tondello,
   G.; Naletto, G.
Bibcode: 1993BAAS...25.1209B
Altcode:
  No abstract at ADS

Title: HiRES: High Resolution Extreme Ultraviolet Spectroheliometer.
Authors: Berger, T.; Bergamini, P.; Kirby, H.; Timothy, J. G.; Walker,
   A. B. C.; Bhattacharyya, J. C.; Jain, S. K.; Saxena, A. K.; Huber,
   M. C. E.; Naletto, G.; Tondello, G.
Bibcode: 1993uxrs.conf..289B
Altcode: 1993uxsa.conf..289B
  The HiRES sounding rocket payload is designed to obtain very high
  spatial, spectral, and temporal resolution images of the solar
  chromospheric and coronal plasmas in the extreme ultraviolet (EUV)
  wavelength range from 500 to 650 Å. The instrument consists of a 450
  mm f/15 Gregorian telescope feeding a 1-m normal incidence stigmatic
  spectrometer. The stigmatic spectrometer utilizes a toroidal diffraction
  grating formed by a unique elastic substrate deformation technique
  in order to achieve simultaneous spatial and spectral focusing at
  two points on the detector plane. Spatial resolution on the order
  of 0.4 arcsecond across a 3×3 arcmin<SUP>2</SUP> field of view is
  obtained. Temporal resolution of the order of milliseconds is achieved
  by the use of an advanced imaging Multi-Anode Microchannel Array
  (MAMA) detector. A hydrogen-alpha 6562.8 Å camera and a 0.25-m EUV
  solar irradiance spectrometer are also included in the payload.

Title: Vainu Bappu Telescope
Authors: Bhattacharyya, J. C.; Rajan, K. T.
Bibcode: 1992BASI...20..319B
Altcode:
  No abstract at ADS

Title: Design and test of a High-Resolution EUV Spectroheliometer
Authors: Berger, Thomas E.; Timothy, J. G.; Walker, Arthur B. C., Jr.;
   Kirby, Helen; Morgan, Jeffrey S.; Jain, Surendra K.; Saxena, Ajay K.;
   Bhattacharyya, Jagadish C.; Huber, Martin C. E.; Tondello, Giuseppe
Bibcode: 1992SPIE.1546..446B
Altcode: 1992SPIE.2011..446B
  The HiRES High-Resolution EUV Spectroheliometer is a sounding rocket
  instrument yielding very high spatial, spectral, and temporal resolution
  images of the solar outer atmosphere, on the basis of a 45-cm Gregorian
  telescope feeding a normal-incidence stigmatic EUV spectrometer with
  imaging multianode microchannel-array detector system, as well as an
  IR spectrometer with imaging CCD detector system. Attention is given
  to the expected performance of this system, including the effects of
  vibrational misalignments due to the sounding rocket flight environment.

Title: HiRES: a high-resolution stigmatic extreme ultraviolet
    spectroheliometer for sudies of the fine-scale structure of the
    solar chromosphere, transition region, and corona.
Authors: Timothy, J. G.; Berger, Thomas E.; Morgan, Jeffrey S.;
   Walker, Arthur B. C., Jr.; Jain, Surendra K.; Saxena, Ajay K.;
   Bhattacharyya, Jagadish C.; Huber, Martin C. E.; Tondello, Giuseppe;
   Naletto, Giampiero
Bibcode: 1991OptEn..30.1142T
Altcode:
  The authors describe the design of a high-resolution stigmatic
  extreme-ultraviolet spectroheliometer, which consists of a 45 cm
  Gregory telescope coupled to a spectrometer employing a single toroidal
  diffraction grating in a normal-incidence Rowland circle mounting and
  an imaging pulse-counting multianode microchannel array (MAMA) detector
  system. The spectroheliometer will produce spatially resolved spectra
  of the chromosphere, transition region, and corona with an angular
  resolution of 0.4″or better, a spectral resolution λ/Δλ of about
  10<SUP>4</SUP> in first order, and a temporal resolution of the order
  of seconds. Because of the geometric fidelity of the MAMA detector
  system, the spectroheliometer will be able to determine Doppler shifts
  to a resolution of at least 2 mÅ at wavelengths near 600Å (≡1.0
  km s<SUP>-1</SUP>), depending on the level of the accumulated signal.

Title: A high speed two-star photometer.
Authors: Rao, G. V.; Thomas, V. A.; Babu, V. C.; Kutty, K. R. N.;
   Ashoka, B. N.; Sugumar, S.; Navada, K. C.; Seetha, S.; Marar, T. M. K.;
   Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1991BASI...19...85R
Altcode:
  No abstract at ADS

Title: High-resolution stigmatic EUV spectroheliometer for studies
    of the fine scale structure of the solar chromosphere, transition
    region, and corona
Authors: Timothy, J. Gethyn; Berger, Thomas E.; Morgan, Jeffrey S.;
   Walker, Arthur B.; Bhattacharyya, Jagadish C.; Jain, Surendra K.;
   Saxena, Ajay K.; Huber, Martin C.; Tondello, Giuseppe; Naletto,
   Giampiero
Bibcode: 1991SPIE.1343..350T
Altcode:
  No abstract at ADS

Title: Possible good observatory sites in India.
Authors: Bhattacharyya, J. C.
Bibcode: 1991nlt..work...99B
Altcode:
  No abstract at ADS

Title: Solar eclipses - A powerful tool for the study of nature
Authors: Bhattacharyya, J. C.
Bibcode: 1990IJRSP..19..525B
Altcode:
  A brief review is presented concerning the phenomena of solar
  eclipses. Discussions on solar eclipse durations and tracks of
  totality, as well as the Saros periodic repetitions of eclipses
  are included. Scientific experiments conducted during total solar
  eclipses are then examined. The experiments cover the measurement of
  astronomical, geophysical, and physiological phenomena. Finally, the
  importance of eclipses in scientific research is briefly reviewed. It
  is concluded that solar eclipses still provide the most convenient
  means for studying the outer layers of the sun and the response of
  the earth atmosphere to the energy flux radiated by it.

Title: A high-speed two-star photometer.
Authors: Rao, G. V.; Thomas, V. A.; Babu, V. C.; Kutty, K. R. N.;
   Ashoka, B. N.; Sugumar, S.; Navada, K. C.; Seetha, S.; Marar, T. M. K.;
   Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1990BASI...18...79R
Altcode:
  Design and performance of a high-speed two-star photometer are
  presented. It is an ideal instrument for investigations of time
  variations of variable stars.

Title: Some further characteristics of observing conditions at Leh
Authors: Singh, Jagdev; Bhattacharyya, J. C.; Babu, G. S. D.;
   Appakutti, M.; Kuppuswamy, K.
Bibcode: 1990BASI...18....7S
Altcode:
  The sky conditions were monitored and duration of photometric and
  spectroscopic hours determined on 198 nights during the period September
  1984 to October 1986. Observations were continued from May till
  November 1987 and again from June to October 1988, when additionally
  the temperature and relative humidity values were systematically
  recorded. Several standard stars were monitored on several nights
  to determine the extinction coefficients in UBV bands; in addition,
  sky brightness was measured on eight nights in the months of September
  and October 1988. The values of sky brightness appear to be marginally
  higher than at La Palma. The average values of extinction coefficients,
  determined on 27 nights during 1988 show a general agreement with the
  earlier values.

Title: Book-Review - Practical Ephemeris Calculations
Authors: Montenbruck, O.; Bhattacharyya, J. C.
Bibcode: 1990BASI...18..103M
Altcode:
  No abstract at ADS

Title: Atmospheric extinction measurements at Leh in near infrared
    bands
Authors: Bhattacharyya, J. C.; Scaria, K. K.; Singh, Jagdev; Babu,
   G. S. D.; Nair, R. Muraleedharan
Bibcode: 1990BASI...18....1B
Altcode:
  Site survey observations to determine the extinction in the IR bands
  were carried out at Leh. Mean extinction coefficients obtained from
  'two nights' observations in J, H, and K bands are k(J) = 0.05 + or -
  0.01; k(H) = 0.04 + or - 0.01; and k(K) = 0.04 + or - 0.01.

Title: Further photometric observations of AM CVn.
Authors: Seetha, S.; Ashoka, B. N.; Marar, T. M. K.; Padmini, V. N.;
   Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.; Bhatt, B. C.;
   Paliwal, D. C.; Pandey, A. K.
Bibcode: 1990apcb.conf..139S
Altcode: 1990cvlm.proc..139S
  About 18 hours of high-speed photometric data was collected during
  April 1989 to determine the true nature of the 1051 s period of AM
  CVn. Raw data reveals 0.05 mag amplitude variations. Results of the
  period analysis are presented. Combining published data with their own,
  the authors derive the rate of decrease as (3.7±0.4)×10<SUP>-12</SUP>s
  s<SUP>-1</SUP>.

Title: High-speed photometry of PG 1711+336 (V795 Her).
Authors: Ashoka, B. N.; Seetha, S.; Marar, T. M. K.; Padmini, V. N.;
   Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.; Bhatt, B. C.;
   Paliwal, D. C.; Pandey, A. K.
Bibcode: 1990apcb.conf..243A
Altcode: 1990cvlm.proc..243A
  Fast photometric observations of PG 1711+336 are presented. The light
  curve shows a periodic modulation of ≡2.8 hr. Although variations of
  ≡0.15 mag, on timescales of ≡10-12 min, are evident throughout the
  light curve, a search for periodicities in the range 500-1500 s did not
  reveal any coherent short period in the system. The authors also report
  that the photometric phase (0.3) of the relatively large-amplitude
  (0.2 mag) decrease in the light, lasting for ≡10 to 15 min, coincides
  in phase with the decrease in equivalent width of a few Balmer lines
  determined by Rosen et al. (1989).

Title: HDE 245770
Authors: Bhattacharyya, J. C.; Ghosh, K. K.; Rao, N. K.; Prabhu,
   T. P.; Mayya, Y. D.; Kuppuswamy, K.; Muniandi, A.
Bibcode: 1989IAUC.4913....1B
Altcode: 1989IAUC.4913....0B
  J. C. Bhattacharyya, Indian Institute of Astrophysics, Bangalore,
  telexes: "K. K. Ghosh, N. K. Rao, T. P. Prabhu, Y. D. Mayya,
  K. Kuppuswamy, and A. Muniandi obtained CCD spectra of the Be x-ray
  binary HDE 245770 (= A0535+26) with the 1-m reflector of Vainu Bappu
  Observatory, Kavalur, between Nov. 22 and 25. The spectra displayed
  emission lines of H-alpha, C II (657.8, 658.2 nm), and He I (667.8
  nm). Presence of C II emission lines suggests that either an outburst
  of the Be star (Baade et al. 1988, A.Ap. 198, 211) or x-ray emission
  from the compact companion (Ghosh et al. 1989, Ap.J. 344, 437) has
  taken place. Ultraviolet and x-ray observations would be of interest."

Title: Nova Scuti 1989
Authors: Bhattacharyya, J. C.; Jain, S. K.
Bibcode: 1989IAUC.4881....2B
Altcode: 1989IAUC.4881....0B
  J. C. Bhattacharyya, Indian Institute of Astrophysics, Bangalore,
  telexes: "S. K. Jain obtained polarimetric V-band observations with
  the 1-m reflector at Vainu Bappu Observatory, Kavalur. An average of
  two data sets on Oct. 7.59 UT indicates a polarization of 3.68 +/-
  0.22 percent at p.a. 178.4 +/- 1.7 deg. A single set on Oct. 9.56
  indicates 1.47 +/- 0.19 percent at p.a. 175.7 +/- 3.6 deg."

Title: 27 Canis Majoris
Authors: Ghosh, K. K.; Kuppuswamy, K.; Bhattacharyya, J. C.
Bibcode: 1989IAUC.4881....3G
Altcode:
  Bhattacharyya also reports: "K. K. Ghosh and K. Kuppuswamy obtained
  echelle CCD spectra on Oct. 14 and 15 of the Be-type star 27 CMa in
  the region of H-alpha, Si (634.7, 637.1 nm), and He I (587.6 nm) that
  suggest this star has entered into a shell phase when compared to the
  previous observations (IAUC 4777). The spectra were obtained with the
  1-m telescope at Vainu Bappu Observatory, Kavalur."

Title: Observing conditions for optical astronomy at Leh
Authors: Singh, Jagdev; Bhattacharyya, J. C.; Babu, G. S. D.; Ashoka,
   B. N.; Appakutty, M.
Bibcode: 1989BASI...17...83S
Altcode:
  The sky and atmospheric conditions at Leh have been monitored since 1984
  with a view to determining its suitability as a site for a high-altitude
  observatory. During May-November, 1987, relative humidity and other
  parameters were monitored giving qualitative indices viz. photometric
  and spectroscopic hours, and seeing conditions throughout the nonwinter
  months. Extinction coefficients in UBV bands have been measured on 30
  nights in 1987. The average values of extinction coefficients are k(v)
  = 0.18 + or - 0.05 (s.d.), k(b) = 0.28 + or - 0.04, and k(u) = 0.53 +
  or - 0.04. These values agree well with those reported earlier for
  1985-1986, and appear to represent consistent conditions.

Title: Optical telescopes in India.
Authors: Bhattacharyya, J. C.
Bibcode: 1989IJPAP..27..311B
Altcode:
  Fabrication and use of optical telescopes for astronomical observations
  in India have been reviewed. Evolution of telescopes, their optics,
  mounting and drive system leading to large aperture instruments of
  today has been described. Limitations of ground-based observations in
  spectral coverage and degradation of images have been discussed. The
  article describes all existing telescope installations in India and
  various efforts made in the country in fabrication of telescopes for
  astronomical use. A brief account of the project by which the 2.34
  metre telescope was constructed is given. Some of the proposals for
  future telescopes are mentioned.

Title: MU Centauri
Authors: Bhattacharyya, J. C.; Ghosh, K. K.; Kuppuswamy, K.;
   Ramachandran, A.; Rajkumar, K.; Ravi, K.; Dinakaran, N.
Bibcode: 1989IAUC.4806....3B
Altcode: 1989IAUC.4806....0B
  J. C. Bhattacharyya, Indian Institute of Astrophysics, Bangalore,
  reports: "CCD spectroscopic observations with the echelle spectrograph
  at the coude focus of the 1-m reflector at Vainu Bappu Observatory,
  obtained by K. K. Ghosh, K. Kuppuswamy, A. Ramachandran, K. Rajkumar,
  K. Ravi, and N. Dinakaran, revealed that the recurrent, transient
  Be-type star mu Cen developed H-alpha emission between Apr. 15 (H-alpha
  asymmetric absorption) and June 22 (centrally-reversed H-alpha, V/R
  about 1). By June 24 the H-alpha emission strength had definitely
  increased."

Title: 27 Canis Majoris
Authors: Bhattacharyya, J. C.; Ghosh, K. K.
Bibcode: 1989IAUC.4777....3B
Altcode: 1989IAUC.4777....0B
  J. C. Bhattacharyya, Indian Institute of Astrophysics reports: "CCD
  echelle spectra obtained by K. K. Ghosh using the 1.02-m telescope at
  Vainu Bappu Observatory, Kavalur, of the Be star 27 CMa at a disperson
  of 0.7 nm/mm during Apr. 16-26 show H-alpha and He I (587.6 nm) lines
  with P-Cyg profiles that appear variable. Earlier observations by him
  (1985-1989 Jan.) showed typical double-peaked H-alpha emission for
  this star."

Title: Indian Institute of Astrophysics. Annual report 1988 - 89.
Authors: Bhattacharyya, J. C.
Bibcode: 1989iiaa.book.....B
Altcode:
  No abstract at ADS

Title: Variable stars in the old galactic cluster M 67.
Authors: Rajamohan, R.; Bhattacharyya, J. C.; Kuppuswamy, K.;
   Subramanian, V.
Bibcode: 1988BASI...16..139R
Altcode:
  Schmidt plates of the old open galactic cluster M67 were obtained on
  twelve nights to find the most probable variables in the cluster. The
  Sabattier technique was used to derive the magnitudes of the cluster
  members. The most probable variable stars in this cluster determined
  by this method are listed.

Title: Editorial
Authors: Bhattacharyya, J. C.
Bibcode: 1988JApA....9D...1B
Altcode:
  No abstract at ADS

Title: Project Kalki - A sky survey with the Schmidt telescope. II
Authors: Rajamohan, R.; Shankar, P. N.; Bhattacharyya, J. C.;
   Kuppuswamy, K.; Paranjpye, A.
Bibcode: 1988BASI...16...21R
Altcode:
  The region of the sky photographed with the 45cm Schmidt telescope
  during 1987 March-May and the position of the asteroids detected
  on these plates are reported in this paper. Out of the 29 asteroids
  observed four have received new temporary designations from the Minor
  Planet Center : 1987 FY1, 1987 FZ1, 1987 HQ2 and 1987 HR2.

Title: Extinction measurements at Leh.
Authors: Singh, J.; Bhattacharyya, J. C.; Raveendran, A. V.; Mohin,
   S.; Ashoka, B. N.; Rajamohan, R.; Jayakumar, K.; Rozario, M. J.;
   Kupuswamy, K.; Paranjpye, A.; Appakutty, M.; Pukalenthi, S.; Muniandi,
   A.; Murthy, V.; Selvakumar, G.
Bibcode: 1988BASI...16...15S
Altcode:
  Observations were started at Leh in 1984 with a view to finding the
  possibility of setting up an astronomical observatory for infrared
  observations. Results of extinction measurements in UBV bands obtained
  on 12 nights during 1985-86 are presented. The average values of
  extinction coefficients are: k(v) = 0.20 + or - 0.13 (s.d.), k(b) =
  0.29 + or - 0.04 and k(u) = 0.53 + or - 0.03.

Title: Extinction Measurements at Leh
Authors: Singh, J.; Bhattacharyya, J. C.; Raveendran, A. V.; Mohin,
   S.; Ashoka, B. N.; Rajamohan, R.; Jayakumar, K.; Rozario, M. J.;
   Kupuswamy, K.; Paranjpye, A.; Appakutty, M.; Pukalenthi, S.; Muniandi,
   A.; Murthy, V.; Selvakumar, G.
Bibcode: 1988BASI...16...16S
Altcode:
  No abstract at ADS

Title: Step towards new technology telescope - CLIMB I.
Authors: Saxena, A. K.; Bhattacharyya, J. C.
Bibcode: 1988BASI...16Q..87S
Altcode:
  No abstract at ADS

Title: Solar Physics in India.
Authors: Krishan, V.; Bhattacharyya, J. C.
Bibcode: 1988sscd.conf..296K
Altcode:
  No abstract at ADS

Title: New instrumentation efforts in solar studies.
Authors: Bhattacharyya, J. C.
Bibcode: 1988KodOB...9..133B
Altcode:
  The techniques of solar studies aim at high magnifications and
  resolutions, extremely high dispersion spectroscopy and experiments to
  unveil the mysteries of a variety of weak but vital physical processes
  which hold clues to our understanding the nature of cosmos.

Title: Flares on AM Canum Venaticorum.
Authors: Marar, T. M. K.; Padmini, V. N.; Seetha, S.; Narayanan Kutty,
   K. R.; Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1988A&A...189..119M
Altcode:
  AM CVn, an interacting binary system consisting of two helium white
  dwarfs, has been classified as a nova-like object. Normally it
  exhibits only small amplitude modulations of 0.05 mag with a 1051 s
  periodicity. The authors report what is believed to be for the first
  time, two unusually intense optical flares in AM CVn during 1985 -
  87. The characteristics of the two flares in white light observed on
  1985 February 24 and 1986 February 7 with Δm = 0.34 and Δm = 1.07
  respectively are described. The authors estimate the maximum amount
  of energy released from these flares as 2.7×10<SUP>36</SUP>erg and
  suggest in the light of current models possible sites of origin of
  the flaring activity.

Title: Project Kalki - a Sky Survey with 45-CM Schmidt Telescope -
    Part One
Authors: Rajamohan, R.; Bhattacharyya, J. C.; Kuppuswamy, K.;
   Paranjpye, A.
Bibcode: 1987BASI...15..174R
Altcode:
  A brief description of the sky survey project taken up with the 45
  cm Schmidt telescope of the Vainu Bappu Observatory at Kavalur is
  given. Positions of 11 asteroids detected on plates taken during 1987
  February-March are reported.

Title: Pluto-Charon Mutual Event
Authors: Vasundhara, R.; Bhattacharyya, J. C.
Bibcode: 1987BASI...15...20V
Altcode:
  No abstract at ADS

Title: A Possible Explanation of the Asymmetry in the Immersion and
    Emersion Light Curves at 12.5 Saturn Radii
Authors: Vasundhara, R.; Bhattacharyya, J. C.
Bibcode: 1987BeiGe..96...52V
Altcode:
  No abstract at ADS

Title: A possible explanation of the asymmetry in the immersion and
    emersion light curves at 12.5 Saturn radii
Authors: Vasundhara, R.; Bhattacharyya, J. C.
Bibcode: 1987oeps.proc...52V
Altcode:
  The absorption features seen in the immersion and emersion light
  curves at 12.5 Saturn radii have antisymmetric wings. These give rise
  to dissimilarity in the two light curves. The antisymmetric wings
  may arise as a reuslt of absorption by extinction lanes having large
  vertical extent. From the duration of the wings an upper limit has
  been set on the possible vertical thickness of these extinction zones.

Title: Plume-like structures of extinction clouds at 19 Saturn radii
Authors: Vasundhara, R.; Bhattacharyya, J. C.; Rozario, M.
Bibcode: 1986BASI...14..232V
Altcode:
  Observations of the occultation of the star SAO 158763 by Saturn's
  magnetospheric region around 19 R<SUB>S</SUB> on 1984 May 12
  are compared with the observations by Mahra et al. of the same
  event. Certain disparities between the Naini Tal and Kavalur data
  suggest that the extinction signatures are more likely to be caused
  by irregular density enhancements of ions, charged dust grains, or
  gas rather than regular ring systems confined to the equatorial plane.

Title: Planetary Occultations
Authors: Brahic, A.; Grenier, I.; McLaren, R.; Grundseth, B.;
   Bhattacharyya, J. C.; Vasundhara, R.; Kuppuswamy, K.; Tholen, D. J.
Bibcode: 1986IAUC.4207....2B
Altcode:
  A. Brahic, I. Grenier, R. McLaren and B. Grundseth report their
  observation of the Apr. 23 occultation N39 by Neptune (Mink and
  Klemola 1985, A.J. 90, 1894). Continuous photometry at 2.2 micron was
  obtained with the 3.6-m Canada-France-Hawaii telescope at Mauna Kea
  from 11h06m to 15h00m UT with 50-ms sampling. The actual occultation
  lasted from 13h01m to 13h35m (preliminary analysis), and no obvious
  secondary events are visible in the raw data. J. C. Bhattacharyya,
  Indian Institute of Astrophysics, telexes that R. Vasundhara and
  K. Kuppuswamy photoelectrically recorded the Apr. 26 occultation of
  AGK3 +23 1108 by (1) Ceres (Wasserman et al. 1985, A.J. 90, 2124)
  with the 1-m telescope at Vainu Bappu Observatory, Kavalur. The event
  lasted from 16h56m12s to 16h58m07s (+ 1s) UT, with a 0.24 +/- 0.05 mag
  drop in light (V filter). D. J. Tholen informs us that the Pluto/Charon
  occultation P4 on Apr. 30 (IAUC 4203, 4206) did not occur at Mauna Kea.

Title: A Single-Channel Polarimeter
Authors: Jain, S. K.; Bhattacharyya, J. C.
Bibcode: 1986IAUS..118...95J
Altcode:
  The authors have developed a single-channel photopolarimeter to measure
  polarization to ≡1%, with an accuracy of 0.1%. Laboratory tests show
  that the performance of the instrument matches the requirements.

Title: New Telescopes in India
Authors: Bhattacharyya, J. C.
Bibcode: 1986Ap&SS.118...45B
Altcode:
  The review covers the description and present status of the two
  optical/infrared telescopes designed and presently near fabrication in
  India. The 234 cm aperture optical telescope expected to be installed at
  Kavalur shortly has several interesting features in its control and data
  acquisition systems. Design features of the 122 cm Infrared Astronomical
  Telescope expected to be completed next year are described. The review
  also covers the Ooty Synthesis Radio Telescope and the Gauribidanur Low
  Frequency Array operating at 327 and 34 MHz, respectively, and a 10 m
  aperture millimeter wave telescope being built in Bangalore. Plans and
  preparations for still bigger systems for observations in different
  bands of Electromagnetic spectra are also briefly described.

Title: Detection of an extremely active state of AM Canum Venaticorum.
Authors: Narayanan Kutty, K. R.; Marar, T. M. K.; Padmini, V. N.;
   Seetha, S.; Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.;
   Mohin, S.; Jayakumar, K.
Bibcode: 1986ASSL..128..397N
Altcode: 1986hdsr.proc..397N; 1986ASSL..128..397K; 1986IAUCo..87..397N
  Fast photometric observations of AM Canum Venaticorum (AM CVn),
  the ultrashort-period, hydrogen-deficient variable, are reported. An
  intense flare of (Delta m) peak roughly 0.34 was detected on February
  24th, 1985 in white light lasting over 200 s. Following this flare,
  an enhanced double-humped structure lasting for 1051 s was observed
  which is the dominant periodicity exhibited by AM CVn. The 525 s and
  1051 s periods were also detected. In addition, the authors report
  flickerings lasting typically 1-2 minutes that are characteristic of
  cataclysmic variables.

Title: Measurement of solar magnetic fields.
Authors: Bhattacharyya, J. C.; Balasubramaniam, K. S.
Bibcode: 1986KodOB...6...30B
Altcode:
  The paper reviews several methods of estimation of solar magnetic fields
  so far employed. The possibility of measurement of the vector magnetic
  fields by using two dimensional detector arrays is discussed. A program
  for vector measurements of strong fields around solar active regions
  is described and an experiment for determining the errors in these
  measurements is discussed.

Title: Identification of emission bands in P/Halley.
Authors: Bhattacharyya, J. C.; Babu, G. S. D.; Ghosh, K. K.; Jayakumar,
   K.; Appakutty, M.
Bibcode: 1986CSci...55..761B
Altcode:
  No abstract at ADS

Title: Proceedings of the national workshop on solar physics, held
    at Kodaikanal, India, 4 - 6 September 1985.
Authors: Sastry, C. V.; Krishan, V.; Bhattacharyya, J. C.
Bibcode: 1986pnwo.book.....S
Altcode:
  No abstract at ADS

Title: Photometry of Intermediate Polars Ao-Piscium and
    V1223-SAGITTARII
Authors: Padmini, V. N.; Marar, T. M. K.; Seetha, S.; Padmanabhan,
   P.; Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.; Kuppuswamy,
   K.; Rozario, M. J.
Bibcode: 1985Ap&SS.117..287P
Altcode:
  We present optical photometric observations of the cataclysmic
  variables AO Psc and V 1223 Sgr, both of which are believed to contain
  slowly-rotating white-dwarf pulsars. These objectes belong to the
  new class of intermediate polars in which the magnetized-white-dwarf
  rotation period lies in between synchrous and extremely fast rotation
  periods. The observations reported here were carried out from the
  Kavalur Observatory using a 1 m reflector. High-time resolution
  light curves depicting a rich variety of flicker phenomena are
  presented. Results of a periodic analysis to search for coherent
  periodic modulations in the light curves are also presented. We have
  also derived the optical pulse profile of AO Psc and point out its
  similarities to the X-ray pulse profile.

Title: Gravitational Instability of Interstellar Magnetic Clouds
Authors: Ghosh, K. K.; Bhattacharyya, J. C.
Bibcode: 1985Ap&SS.117...89G
Altcode:
  The gravitational instability of a nonrotating isothermal gaseous disk
  permeated by a uniform frozen-in magnetic field is investigated using
  a fourth-order perturbation technique. From the results it is found
  that the disk is stable whenn/B <SUB>0</SUB> &lt; (4/3π<SUP>3</SUP>
  G)<SUP>-1/2</SUP>, wheren andB are the column density of the disk and
  unperturbed magnetic field, respectively, andG is the gravitational
  constant. The disk is gravitationally unstable only whenn/B <SUB>0</SUB>
  &gt; (4/3π<SUP>3</SUP> G)<SUP>-1/2</SUP>.

Title: High Speed Photometry of SS Cygni after an Outburst
Authors: Seetha, S.; Padmini, V. N.; Marar, T. M. K.; Kasturirangan,
   K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1985IBVS.2839....1S
Altcode:
  No abstract at ADS

Title: Measurement of Vector Magnetic Fields - Part One - Theoretical
    Approach to the Instrumental Polarization of the Kodaikanal Solar
    Tower
Authors: Balasubramaniam, K. S.; Venkatakrishnan, P.; Bhattacharyya,
   J. C.
Bibcode: 1985SoPh...99..333B
Altcode:
  The observations of Stokes line profiles require an accurate knowledge
  of the instrumental polarisation caused by optical components in the
  path of the light beam. In this context we present a theoretical
  approach to the instrumental polarisation caused by the 3-mirror
  coelostat system of the Kodaikanal Solar Tower.

Title: Search for Optical Bursts from the Gamma Ray Source GBS 0526-66
Authors: Seetha, S.; Sreenivasaiah, K. V.; Marar, T. M. K.;
   Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1985ICRC....1...23S
Altcode: 1985ICRC...19a..23S
  Attempts were made to detect optical bursts from the gamma-ray
  burst source GBS 0526-66 during Dec. 31, 1984 to Jan. 2, 1985
  and Feb. 23 to Feb. 24, 1985, using the one meter reflector of the
  Kavalur Observatory. Jan. 1, 1985 coincided with the zero phase of the
  predicted 164 day period of burst activity from the source (Rothschild
  and Lingenfelter, 1984). A new optical burst photon counting system
  with adjustable trigger threshold was used in parallel with a high
  speed photometer for the observations. The best time resolution was 1
  ms and maximum count rate capability was 255,000 counts s(-1). Details
  of the instrumentation and observational results are presented.

Title: The microprocessor control of the Kavalur 234-cm optical
    telescope
Authors: Chinnappan, V.; Bhattacharyya, J. C.
Bibcode: 1985BASI...13..153C
Altcode:
  This paper gives an introduction to the control system of the 234-cm
  optical telescope. The computer used in control is based on an
  INTEL 16 bit microprocessor. The VAX 11/780 system has a supervisory
  role in the control system and is used primarily to calculate the
  pointing errors due to mechanical imperfections of the telescope,
  atmospheric refraction, and other similar errors. The microcomputer
  and the VAX system are coupled with bidirectional drivers and exchange
  data at predetermined sidereal intervals. The various tasks involved
  in the control of the telescope are explained. The interface circuits
  developed at the electronics laboratory are briefly mentioned. Circuits
  necessary for the display to telescope position, celestial coordinates,
  and sidereal time are included.

Title: Photometry of intermediate polars V1223 Sgr and H 2252-035.
Authors: Marar, T. M. K.; Seetha, S.; Padmanabhan, P.; Padmini, V. N.;
   Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.; Kuppuswamy, K.;
   Rozario, M. J.
Bibcode: 1985BASI...13...83M
Altcode:
  No abstract at ADS

Title: Astronomy in India in the 20th century.
Authors: Bhattacharyya, J. C.; Vagiswari, A.
Bibcode: 1985InJHS..20..403B
Altcode:
  No abstract at ADS

Title: A fast optical pulse counting system for Crab pulsar.
Authors: Santhanam, P.; Bhattacharyya, J. C.
Bibcode: 1985KodOB...5...27S
Altcode:
  A sub-millisecond resolution counting system for recording shapes of
  short periodic pulses is described. Results obtained in recording the
  shape of optical pulses from Crab pulsar are given. The flexibility
  of the system for multi-channel photoelectric photometry application
  is explained.

Title: Outer rings of Saturn.
Authors: Bhattacharyya, J. C.; Vasundhara, R.
Bibcode: 1985CSci...54...60B
Altcode:
  No abstract at ADS

Title: Possible detection of a ring system in Saturn's magnetosphere
Authors: Vasundhara, R.; Bhattacharyya, J. C.; Santhanam, P.; Pande,
   A. K.; Mohan, Vijay; Mahra, H. S.
Bibcode: 1984Natur.312..621V
Altcode:
  The region of the magnetosphere of Saturn around 14 radii and 19 radii
  has been of special interest since the detection of anamolous dips in
  the low-energy plasma ion-density in these regions by the Voyager 1,
  Voyager 2 and Pioneer 11 spacecrafts. Lazarus et al. suggested that
  these density dips may be due to long-lived particulate or gaseous
  structures in the equatorial plane of Saturn<SUP>1</SUP>. Baron and
  Elliot, using the charge-coupled device (CCD) imaging technique,
  found no evidence of any material existing between 10 and 36 Saturn
  radii<SUP>2</SUP>. Their negative results, however, have set an
  upper limit on the extent of a possible material cloud with several
  assumptions regarding its nature and density. We have observed the
  occultation of the star SAO158913 from two stations in India following
  predictions by Mink<SUP>3</SUP>. This star showed symmetric dips in
  the light curves on 24 March 1984 (immersion event) and on 25 March
  1984 (emersion event), suggesting the possible presence of particulate
  matter.

Title: Possible Occultation by Saturnian Magnetospheric Ring
Authors: Bhattacharyya, J. C.; Santhanam, P.; Rozario, M. J.
Bibcode: 1984IAUC.3941....2B
Altcode: 1984IAUC.3941....0B
  J. C. Bhattacharyya, Indian Institute of Astrophysics, Bangalore,
  reports that observations by Santhanam and Rozario with the 1-m
  telescope at Kavalur indicate systematic extinction of SAO 158913
  on March 24 and 25, apparently in accordance with the prediction by
  Mink (1983, A.J. 88, 559) of occultations of the star by the supposed
  magnetospheric ring at 14 radii from the center of Saturn. Observations
  on Mar. 24 in integrated light showed two prominent and several
  smaller and narrow absorbing features beween 20h14m and 20h20m UT,
  the maximum extinction being 0.58 mag. Observations on Mar. 25 using
  a B filter showed similar structures between 20h18m and 20h24m with
  a maximum extinction of 0.28 mag.

Title: Minor planets and planetary rings.
Authors: Bhattacharyya, J. C.
Bibcode: 1984bims.symp...95B
Altcode:
  Circumstances of the discovery of the first asteroid and the
  characteristics of various orbits followed by them have been
  discussed. Their shapes, compositions and evolutionary histories so
  far known have also been described. The review also covers the present
  status of knowledge about the rings surrounding 3 giant planets.

Title: Das Ringsystem des Planeten Uranus - eine bemerkenswerte
    Entdeckung im Sonnensystem.
Authors: Bhattacharyya, J. C.
Bibcode: 1984JenRu..29..114B
Altcode:
  No abstract at ADS

Title: Evidence for interpulses between photometric maxima of EX Hya.
Authors: Sharma, D. P.; Marar, T. M. K.; Seetha, S.; Padmini, V. N.;
   Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.; Rajamohan, R.
Bibcode: 1984BASI...12S..63S
Altcode:
  No abstract at ADS

Title: Thrust areas in astronomy and astrophysics
Authors: Bhattacharyya, J. C.; Venugopal, V. R.
Bibcode: 1984taaa.book.....B
Altcode: 1984QB43.2.B48.....
  No abstract at ADS

Title: Magnetic field - plasma interaction on the Sun. Proceedings of
    a colloquium held at Kodaikanal on January 23, 1984 in commemoration
    of the 75th anniversary of the discovery of the Evershed effect.
Authors: Sivaraman, K. R.; Raju, P. K.; Bhattacharyya, J. C.;
   Howard, R.
Bibcode: 1984mafi.book.....S
Altcode:
  No abstract at ADS

Title: Indications of Twist in the Epsilon Ring of Uranus
Authors: Vasundhara, R.; Bhattacharyya, J. C.
Bibcode: 1984plri.coll..193V
Altcode: 1984IAUCo..75..193V; 1984prin.conf..193V
  A comparison of light curves during stellar occultations by the ɛ
  ring of Uranus indicates that this ring assembly possesses stable fine
  structures. The authors discuss the possibility that the ring contains
  a twisted bundle of narrow lanes of condensed material similar to that
  of Saturn's F ring.

Title: Observations of X-Persei in Optical Domain
Authors: Sharma, D. P.; Nagaraja, B. V.; Bhattacharyya, J. C.; Mohin,
   S.; Raveendran, A. V.
Bibcode: 1983Ap&SS..95...65S
Altcode:
  We have monitored the X-ray source X-Per (4U 0352+30) on 31 August, 1979
  through aU filter for about 1.5 hr using 102-cm telescope of Kavalur
  observatory. During this period intensity of X-Per fluctuated for
  some time, on time scales of few minutes but recovered in the end. It
  was again monitored from 27 December, 1979 to January 1980 through a
  standardU, B, V photometer attached to a 34-cm telescope. In this paper
  we present the data on the fast flickerings observed on 31 August,
  1979 and on the long term monitoring from December 1979 to January 1980.

Title: Some Further Measurements of Uranian Ring Condensations
Authors: Vasundhara, R.; Bhattacharyya, J. C.; Rajamohan, R.; Mahra,
   H. S.
Bibcode: 1983M&P....29...79V
Altcode:
  The results of photometric observations of the occultation of BD-19°
  4222 by Uranus on April 26, 1981 from two stations in India conform
  with the model proposed by Elliotet al. (1981).

Title: Photometric Observations of the X-Ray Dwarf Nova HL Canis
    Majoris
Authors: Seetha, S.; Marar, T. M. K.; Sharma, D. P.; Kasturirangan,
   K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1983ICRC....9....5S
Altcode: 1983ICRC...18i...5S
  High speed optical photometric observations of the X-ray dwarf nova HL
  Canis Majoris (1E 0643-1648), discovered with the Einstein Observatory,
  are presented. Results of long term monitoring and attempts to detect
  photometric eclipses at the reported orbital periods of 0.22 d or 0.18
  d of the binary system are presented.

Title: High speed photometry of dwarf nova EX Hydrae.
Authors: Sharma, D. P.; Marar, T. M. K.; Seetha, S.; Kasturirangan,
   K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1983ICRC....9..330S
Altcode: 1983ICRC...18i.330S
  High speed optical photometric observations of the hard X-ray source
  EX Hya, carried out with the reflector of the Kevalur Observatory, are
  presented. The observations with time resolutions of 1 s or 2 s were
  made on four nights in March 1982 for a total duration of 6.8 h. Light
  curves that reveal fast flickerings and the 67 min oscillations are
  presented. A new ephemeris for the photometric period confirms the trend
  towards decreasing period on a time scale of 10-million years. Evidence
  for the presence of interpulses in the light curves between successive
  photometric maxima is also shown.

Title: Photometric Observations of the X-Ray Dwarf Nova HL Canis
    Majoris
Authors: Seetha, S.; Marar, T. M. K.; Sharma, D. P.; Kasturirangan,
   K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1983ICRC....1...11S
Altcode: 1983ICRC...18a..11S
  No abstract at ADS

Title: Discovery of a Flare Star Near Sirius
Authors: Sharma, D. P.; Marar, T. M. K.; Seetha, S.; Shyla, K. S.;
   Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.; Rozario, M. J.
Bibcode: 1983Ap&SS..91..467S
Altcode:
  The discovery of a flare star
  (R.A. (1950)=6<SUP>h</SUP>43<SUP>m</SUP>6<SUP>s</SUP>.07,
  Decl.(1950)=-16°45'24″) located about 6 arc min south of Sirius is
  reported. During photometric observations on the night of 13 January,
  1982, using the 102 cm telescope at Kavalur, India, the star was
  seen to brighten by 2.55 mag. inV band over a duration of about 200
  s. Observations on this object for a duration of about 10.5 hr spread
  over seven more nights indicate the star to be variable. The results
  of these observations are presented.

Title: Obituary - Bappu, M.K.
Authors: Bhattacharyya, J. C.
Bibcode: 1983QJRAS..24..360B
Altcode: 1983QJRAS..24..360.
  No abstract at ADS

Title: Tribute to the memory of Professor M. K. V. Bappu (August 10,
    1927 - August 19, 1982), given at the XVIIIth General Assembly of
    the IAU.
Authors: Kharadze, E. K.; Bhattacharyya, J. C.; Xanthakis, J.; Goudas,
   C. L.; Blaauw, A.; Smith, H. G.
Bibcode: 1983IAUTB..18....1K
Altcode:
  No abstract at ADS

Title: In memoriam: M. K. V. Bappu (1927-1982).
Authors: Bhattacharyya, J. C.
Bibcode: 1983Ap&SS..89....3B
Altcode:
  No abstract at ADS

Title: In memoriam
Authors: Bhattacharyya, J. C.
Bibcode: 1983Ap&SS..89D...2B
Altcode:
  No abstract at ADS

Title: High Speed Photometry of Dwarf Nova Ex-Hydrae
Authors: Sharma, D. P.; Marar, T. M. K.; Seetha, S.; Kasturirangan,
   K.; Rao, U. R.; Bhattacharyya, J. C.
Bibcode: 1983ICRC....2..406S
Altcode: 1983ICRC...18b.406S
  No abstract at ADS

Title: Asia's biggest telescope.
Authors: Bhattacharyya, J. G.
Bibcode: 1983InEE..125..274B
Altcode:
  No abstract at ADS

Title: Scientific Objectives of the Observations
Authors: Bhattacharyya, J. C.
Bibcode: 1982tsef.conf....1B
Altcode:
  No abstract at ADS

Title: Notes and News
Authors: Kapahi, V. K.; Sarma, N. V. G.; Bhattacharyya, J. C.
Bibcode: 1981BASI....9..323K
Altcode:
  No abstract at ADS

Title: The second Asian-Pacific regional meeting of astronomy.
Authors: Bhattacharyya, J. C.
Bibcode: 1981BASI....9..328B
Altcode:
  No abstract at ADS

Title: Observations of the total solar eclipse of 16 February
    1980. (Preliminary results).
Authors: Trehan, S. K.; Bhattacharyya, J. C.
Bibcode: 1981otse.conf.....T
Altcode:
  No abstract at ADS

Title: Observations of optical emission from X-Per and SCO X-1
Authors: Sharma, D. P.; Nagaraja, B. V.; Marar, T. M. K.;
   Bhattacharyya, J. C.; Mohin, S.
Bibcode: 1981ICRC....9...13S
Altcode: 1982ICRC....9...13S; 1981ICRC...17i..13S
  High speed photometric observations of X-Per, and Sco X-1 have been
  carried out during 1979-80 with the 102 cm and 33 cm telescopes at
  the Kavalur observatory. Results from some of these observations are
  presented in this paper. Data on long term intensity variations at a
  differential magnitude level of plus or minus 0.1 and fast flickering
  in X-Per are presented and discussed.

Title: Application aspects of time and frequency to astronomy.
Authors: Bhattacharyya, J. C.
Bibcode: 1981JIETE..27..593B
Altcode:
  No abstract at ADS

Title: Determination of the limb darkening of the solar disc in the
    visible and near ultraviolet.
Authors: Bhattacharyya, J. C.; Chandramohan, R.; Sundareswaran, A.;
   Charles, A.
Bibcode: 1981otse.conf....4B
Altcode:
  No abstract at ADS

Title: Total solar eclipse of February 16, 1980.
Authors: Bhattacharyya, J. C.
Bibcode: 1980PINSA..46..191B
Altcode:
  No abstract at ADS

Title: A simple digital system drive for small telescopes.
Authors: Bhattacharyya, J. C.; Ramamoorthy, K. S.; Chandramohan, R.
Bibcode: 1980KodOB...3...26B
Altcode:
  A variable stable frequency source employing a crystal oscillator and a
  programmable digital divider chain is described. The system offers an
  ideal arrangement for controlling tracking rates of small and medium
  size telescopes by which limitations due to mechanical imperfections
  can almost be completely eliminated.

Title: A High Time Resolution Photometer for Optical Monitoring of
    X-Ray Sources
Authors: Sharma, D. P.; Sharma, M. R.; Hathwar, G. R.; Bhattacharyya,
   J. C.
Bibcode: 1979BASI....7..123S
Altcode:
  No abstract at ADS

Title: Extended Ring System of Uranus
Authors: Bhattacharyya, J. C.; Bappu, M. K. V.; Mohin, S.; Mahra,
   H. S.; Gupta, S. K.
Bibcode: 1979M&P....21..393B
Altcode:
  Two photoelectric records of the occultation event on 10 March, 1977,
  obtained by two 102-cm-aperture telescopes, spaced 1500 km apart,
  are critically analysed and indications of a complex structure
  of distribution of occulting material surrounding the planet are
  obtained. The results confirm the existence of a very shallow broad
  ring system with local condensation lanes of narrow and intermediate
  widths. A system of numerous thin rings are also present around the
  planet in the equatorial plane.

Title: Automatic Photon Counting and Printing Device for Small
    Telescopes
Authors: Chandramohan, R.; Bhattacharyya, J. C.
Bibcode: 1979BASI....7..124C
Altcode:
  No abstract at ADS

Title: Total Solar Eclipse of 1980
Authors: Bhattacharyya, J. C.
Bibcode: 1978BASI....6...17B
Altcode:
  No abstract at ADS

Title: Saturn-like ring system around Uranus
Authors: Bhattacharyya, J. C.; Bappu, M. K. V.
Bibcode: 1977Natur.270..503B
Altcode:
  OBSERVATIONS made at Kavalur<SUP>1,2</SUP> of the occultation of
  SAO158687 by Uranus on 10 March 1977 showed, in addition to the
  occultation by a satellite system termed the ɛ ring, a dimming of the
  light of the star close to the time when the atmosphere of the planet
  could have caused the phenomenon. Since then, the identities of the α,
  β, γ, δ rings have also become well established, and a theoretical
  interpretation of their origin<SUP>3</SUP> has been proposed. We have
  closely examined the Kavalur photoelectric record and describe here
  several new features of the satellite ring system of Uranus.

Title: A new satellite of Uranus
Authors: Bhattacharyya, J. C.; Kuppuswamy, K.
Bibcode: 1977Natur.267..331B
Altcode:
  WHILE observing the occultation of the star SAO 158687 by Uranus on 10
  March 1977 we came across an unexpected event suggesting the existence
  of a hitherto unknown satellite of the planet. The observations
  were carried out at the Kavalur Observatory (lat. 12° 34' 32'' N:
  long 78° 49' 54'' E) using a near infrared photometer consisting
  of a refrigerated EMI 9558B phototube and Kodak Wratten 89B filter
  attached to the Cassegrain focus of the 102-cm telescope. The individual
  deflections due to the star and the planet were measured during the
  previous night, as well as a few hours before the predicted instant of
  occultation. A 16-arc s diaphragm was used during occultation, whereby
  the planet and the star could be conveniently contained for several
  hours around the epoch of occultation. Guiding and monitoring of the
  objects were done through the 20-cm guide telescope, with periodic
  checking of the centering in the main telescope. As indicated by the
  prediction<SUP>1</SUP>, we expected only a grazing occultation to be
  visible at Kavalur, resulting in a slight diminution in the intensity
  of starlight owing to the extinction effect by differential refraction
  in the outer layers of the planet's atmosphere<SUP>2</SUP>. A very
  shallow depression of 0.046 magnitudes in the light of SAO 158687 was
  indeed observed.

Title: Occultation of SAO 158687 by Uranian Rings
Authors: Hubbard, W. B.; Zellner, B.; Wasserman, L. H.; Elliot, J. L.;
   Bhattacharyya, J. C.; Kupppswamy, K.
Bibcode: 1977IAUC.3058....1H
Altcode:
  W. B. Hubbard, Lunar and Planetary Laboratory, reports that analysis
  of photometric traces obtained by B. Zellner at the Perth Observatory
  shows the following occultations. These events can be identified with
  occultations observed by Elliot et al., so their notation (cf. IAUC
  3051) is utilized: Event UT Event UT alpha1 20h20m06s alpha2 21h42m21s
  beta2 21 43 38 These timings are preliminary (uncertainty +/- 5s for
  alpha2 and beta2). Nothing of statistical significance appears at the
  times of the events alpha3 and beta3 reported by Millis et al. (IAUC
  3051). Observations were not made around the times of the other reported
  events. L. H. Wasserman, Lowell Observatory, reports that Millis et
  al. could not have observed the alpha1 and delta1 events, for these
  would have taken place at Perth at a few seconds after 20h20m and 20h15m
  UT, respectively, and observations were interrupted for recentering for
  some 5-10 seconds beginning at these exact times. The events alpha3 and
  beta3 were noticeably shallower than the others J. L. Elliot, Cornell
  University, remarks that the events alpha3 and beta3 are probably
  present in the Kuiper Airborne Observatory data but are not at all
  conspicuous. J. C. Bhattacharyya, Indian Institute of Astrophysics,
  reports that the event observed by K. Kupppswamy and himself at Kavalur
  began at 20h19m38s UT (i.e., epsilon5 = 20h19m42s; cf. IAUC 3048,
  3051). The shorter occultations were not noted, and observations had
  ceased by the time of any corresponding events after the Uranus appulse.

Title: Discovery of a New Satellite of Uranus
Authors: Bhattacharyya, J. C.; Kuppuswamy, K.
Bibcode: 1977BASI....5...19B
Altcode:
  No abstract at ADS

Title: Occultation of SAO 158687 by Uranus and Satellite Belt
Authors: Elliot, J. L.; Dunham, E.; Mink, D.; Millis, R. L.; Birch,
   P.; Trout, D.; Bappu, M. K. V.; Bhattacharyya, J. C.; Kuppuswamy;
   Marsden, B. G.
Bibcode: 1977IAUC.3048....1E
Altcode:
  Amplifying the brief announcement on IAUC 3047, J. L. Elliot reports
  that several secondary occultations of SAO 158687 on Mar. 10 were
  observed by E. Dunham, D. Mink and himself from the Kuiper Airborne
  Observatory and also by R. L. Millis, P. Birch and D. Trout at the Perth
  Observatory. Both groups independently concluded that these occultations
  were caused by bodies that are apparently part of a satellite belt
  about 40 000 km distant from the center of Uranus. The diameters of the
  satellites range from 100 km to much smaller values. The occultation by
  Uranus itself was successfully observed from the Airborne Observatory
  (located at Long. = -90o, Lat. = -50o) and lasted ~ 25 min centered
  on 21h06m UT. The Uranus occultation did not occur at the Perth
  Observatory. The secondary occultations took place during an 8-9
  min interval around 20h16m UT and during a similar interval around
  21h50m UT (although dawn prevented observations of the latter events
  in Perth). M. K. V. Bappu, Indian Institute of Astrophysics, cables:
  "Using the 102-cm reflector at Kavalur (Long. = -5h15m19s.6, Lat. =
  +12o34'32"), Bhattacharyya and Kuppuswamy found the diminution of
  SAO 158687 during the occultation by the atmosphere of Uranus to be
  0.046 magnitude at an effective wavelength of 7500 A. Visually and
  photoelectrically they observed the complete disappearance of the star
  for 8s.9 beginning at 20h19m15s UT and ascribe this to obscuration
  by a hitherto unknown satellite of the planet." Computations by the
  undersigned show that the asymmetry in the times of the satellite
  occultations about the main occultation (as observed at the Airborne
  Observatory) is consistent with the existence of a circular belt in
  the plane of Uranus' equator. Allowance for foreshortening yields the
  radii of the inner and outer edges of the belt as 44 000 and 51 000
  km, respectively. The Kavalur observation suggests occultation by a
  100-km-sized body near the outer edge of the belt. Other observers are
  urged to examine their records for further evidence of this belt. At
  Sutherland, times of mid-occultation by the belt would have been
  20h22m and 21h59m UT; at Mauritius, 20h23m and 21h54m; at Lembang,
  20h20m and 21h46m; at Kyoto, 20h22m; at Helwan, 21h56m. Those wishing
  to attempt to detect the satellite belt directly are advised that at
  the present opposition it should be located from 3".5 to 4".0 to the
  north and south of the center of Uranus and from 2".7 to 3".1 to the
  east and west; the brightest bodies in it are expected to have mv ~ 19.

Title: An analog system for fast light curve registration.
Authors: Bhattacharyya, J. C.; Sundareswaran, A.
Bibcode: 1977KodOB...2...69B
Altcode:
  No abstract at ADS

Title: Preliminary results of the structure of Alpha Vir from lunar
    occultation measurements.
Authors: Bhattacharyya, J. C.; Sundareswarn, A.
Bibcode: 1976BASI....4...83B
Altcode:
  No abstract at ADS

Title: Ionospheric electron content and equivalent slab thickness
    in the equatorial region
Authors: Das Gupta, A.; Basu, S.; Bhar, J. N.; Bhattacharyya, J. C.
Bibcode: 1975JGR....80..699D
Altcode:
  No abstract at ADS

Title: Fine structure of photospheric magnetic field and
    Ca<SUP>+</SUP>K<SUB>3</SUB> network.
Authors: Bhattacharyya, J. C.; Saxena, A. K.; Singh, J.
Bibcode: 1975BASI....3R..28B
Altcode:
  No abstract at ADS

Title: A system for recording fast varying light curves.
Authors: Bhattacharyya, J. C.; Sundareswaran, A.
Bibcode: 1975BASI....3Q..28B
Altcode:
  No abstract at ADS

Title: Velocity oscillations of the solar atmosphere at chromospheric
    heights.
Authors: Bhattacharyya, J. C.
Bibcode: 1974BASI....2...40B
Altcode:
  No abstract at ADS

Title: An Atmosphere on Ganymede from Its Occultation of SAO 186800
    on 7 June 1972
Authors: Carlson, R. W.; Bhattacharyya, J. C.; Smith, B. A.;
   Johnson, T. V.; Hidayat, B.; Smith, S. A.; Taylor, G. E.; O'Leary,
   B.; Brinkmann, R. T.
Bibcode: 1973Sci...182...53C
Altcode:
  On 7 June 1972 the third Jovian satellite Ganymede occulted the
  eighth-magnitude star SAO 186800. Successful photoelectric observations
  obtained at Lembang, Java (Indonesia), and Kavalur, India, show
  nonabrupt immersions and emersions, indicating the presence of an
  atmosphere whose surface pressure is greater than about 10<SUP>-3</SUP>
  millibar. By fitting the two occultation durations as chords to a
  model disk, the diameter is found to be 5270 (+30, -~ 200) kilometers,
  the major error contribution arising from the uncertain atmospheric
  thickness below the occultation layer. The derived mean density is 2.0
  (-0.03, + ~ 0.2) grams per cubic centimeter.

Title: Photometry of the solar corona of March 7, 1970.
Authors: Bappu, M. K. V.; Bhattacharyya, J. C.; Sivaraman, K. R.
Bibcode: 1973Prama...1..117B
Altcode:
  No abstract at ADS

Title: On Emission Lines of Hydrogen, Helium and Ionized Calcium
    Seen on a Coronal Spectrogram of the March 7, 1970 Eclipse
Authors: Bappu, M. K. V.; Bhattacharyya, J. C.; Sivaraman, K. R.
Bibcode: 1972SoPh...26..366B
Altcode:
  Emission lines of the Balmer series, D<SUB>3</SUB> and H and K are
  reported present on a coronal spectrogram obtained at the March 7,
  1970 eclipse. Arguments are presented to show that these could not
  have originated from scattering in the Earth's atmosphere and hence
  possibly have a coronal origin.

Title: Occultation of Beta Scorpii by Jupiter on May 13, 1971
Authors: Bhattacharyya, J. C.
Bibcode: 1972NPhS..238...55B
Altcode: 1972Natur.238...55B
  PHOTOELECTRIC observations of the occultation of the star β Scorpii by
  Jupiter were carried out at our field station at Kavalur on the night
  of May 13-14, 1971, at the cassegrain focus of the 38 cm reflecting
  telescope. Our photometric record was made by photographing a CRO trace
  in order to record the true light emission curve during the immersion
  and emersion phases of the occultation. The record was calibrated by
  photographing seconds pulses from a quartz clock simultaneously. A
  thin glass plate behind the focal plane diaphragm allowed continuous
  visual monitoring of the Jovian limb and the occultation phenomenon.

Title: Velocity Oscillations in the Solar Atmosphere
Authors: Bhattacharyya, J. C.
Bibcode: 1972SoPh...24..274B
Altcode:
  From a series of long duration continuous Doppler records of selected
  spectral lines, characteristics of solar velocity oscillations have
  been studied. Statistical distribution of the durations of the bursts
  of oscillations has been estimated. From the nature of distortion of
  the waveforms of the oscillation, the presence of disturbing impulses
  has been speculated. Constancy and homogeneity of the oscillations have
  been examined from detailed spectral density plots. Duration indices
  for the oscillations at different heights in the solar atmosphere have
  been derived by estimating mean spectral densities of characteristic
  oscillation amplitudes during several individual bursts and comparing
  them with corresponding spectral densities from long records. The
  variation among experimental results has been explained as due to the
  limitations of the power spectral analysis method on short records.

Title: Occultation of SAO 186800 by Jupiter III.
Authors: Bhattacharyya, J. C.
Bibcode: 1972IAUC.2412Q...1B
Altcode:
  No abstract at ADS

Title: Ionospheric indication of short-time solar activity variations.
Authors: Bhattacharyya, J. C.; Sunder, R. S.
Bibcode: 1970IJPAP...8..544B
Altcode:
  No abstract at ADS

Title: The solar magnetometer of Kodaikanal Observatory.
Authors: Bhattacharyya, J. C.
Bibcode: 1970KodOB.205..203B
Altcode:
  No abstract at ADS

Title: Spectral characteristics of a solar flare from ionospheric data
Authors: Bhattacharyya, J. C.; Balakeishnan, T. K.
Bibcode: 1967JATP...29.1573B
Altcode:
  From the height variation of electron densities during a solar flare,
  ultra violet and X-ray contribution of ionization process has been
  estimated. The results thus obtained are in conformity with direct
  measurements of solar ultraviolet and X-ray spectra by rocket
  techniques.

