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Browsing by Author "Cowsik, R"

Browsing by Author "Cowsik, R"

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  • A bound on violations of Lorentz invariance 
    Cowsik, R; Sreekantan, B. V (Elsevier Science B. V, 1999-03)
    Recently Coleman and Glashow [Phys. Lett. B 405 (1997) 249; Harvard University Theoretical Physics Preprint 98/AO76 (pvt. comm)] have developed a model which allows the introduction of a small violation of Lorentz invariance. ...
  • CCD imaging of gamma ray burster fields 
    Bhargavi, S. G; Cowsik, R; Pati, A. K; Sagar, R (Astronomical Society of India, 1998)
  • Constraints on stellar grain formation from presolar graphite in the murchison meteorite 
    Bernatowicz, T. J; Cowsik, R; Gibbons, P. C; Lodders, K; Fegley, B. Jr; Amari, S; Lewis, R. S (American Astronomical Society, 1996-12)
    We report the results of isotopic, chemical, structural, and crystallographic microanalyses of graphitic spherules (0.3-9 μm) extracted from the Murchison meteorite. The spherules have sup12C/sup13C ratios ranging over 3 ...
  • Data analysis method for the search of point sources of gamma rays with the HAGAR telescope array 
    Britto, R. J; Acharya, B. S; Anupama, G. C; Bhattacharjee, P; Chitnis, V. R; Cowsik, R; Dorji, N; Duhan, S. K; Gothe, K. S; Kamath, P. U; Mahesh, P. K; Manoharan, J; Nagesh, B. K; Parmar, N. K; Prabhu, T. P; Rao, S. K; Saha, L; Saleem, F; Saxena, A. K; Sharma, S. K; Shukla, A; Singh, B. B; Srinivasan, R; Srinivasulu, G; Sudersanan, P. V; Tsewang, D; Upadhya, S. S; Vishwanath, P. R (French Society of Astronomy and Astrophysics, 2011-12)
    The High Altitude GAmma-Ray (HAGAR) experiment is the highest altitude atmospheric Cherenkov sampling array, set up at 4300 m amsl in the Himalayas (Northern India). It constitutes 7 telescopes, each one with seven 90 ...
  • Detection of Short-Period Coronal Oscillations during the Total Solar Eclipse of 24 October, 1995 
    Singh, J; Cowsik, R; Raveendran, A. V; Bagare, S. P; Saxena, A. K; Sundararaman, K; Krishan, V; Naidu, N; Samson, J. P. A; Gabriel, F (Springer, 1997-02)
    An experiment to search for short-period oscillations in the solar corona was conducted during the total solar eclipse of 1995 October 24 at Kalpi, India. The intensity in the continuum, centred around 5500 Å and with a ...
  • The development of technology for vacuum ultraviolet plane grating monochromator to be used with XUV synchrotron source of INDUS I 
    Saxena, A. K; Cowsik, R (SPIE The International Society for Optical Engineering., 1997)
    The plane grating monochromator is to be used with the 480MeV (lambda(c)=61 Angstrom) consists of a, plane grating, plane minor (500mmx50mm) and an ellipsoidal mirror (300mmx50mm, & semi-major axis 39935.7mm, semi-minor ...
  • Dispersion Velocity of Galactic Dark Matter Particles 
    Cowsik, R; Ratnam, C; Bhattacharjee, P (The American Physical Society, 1996-05)
    The self-consistent spatial distribution of particles of galactic dark matter is derived including their own gravitational potential, as also of that of the visible matter of the Galaxy. In order to reproduce the observed ...
  • Dispersion velocity of Galactic dark matter particles- Reply 
    Cowsik, R; Ratnam, C; Bhattacharjee, P (The American Physical Society, 1997-03)
    A Reply to the Comment by N. W. Evans. Also, Evalyn Gates, Marc Kamionkowski, and Michael S. Turner.
  • Dynamics of dwarf-spheroidals and the dark matter halo of the galaxy 
    Cowsik, R; Ratnam, C; Bhattacharjee, P; Majumdar, S (Elsevier B. V., 2007-08)
    The dynamics of the dwarf-spheroidal (dSph) galaxies in the gravitational field of the Galaxy is investigated with particular reference to their susceptibility to tidal break-up. Based on the observed paucity of the dSphs ...
  • Early Observations of the Afterglow of GRB 000301c 
    Bhargavi, S. G; Cowsik, R (The American Astronomical Society, 2000-12)
    We report multiband observations of the optical transient associated with GRB 000301c carried out 2000 March 2-4 using the 2.34 m Vainu Bappu Telescope at Kavalur, India. When combined with other reported data, the initial ...
  • Galactic Age Estimates from O-rich Stardust in Meteorites 
    Nittler, L. R; Cowsik, R (The American Physical Society, 1997-01)
    The sup16Osup/17 supO and sup16O/sup18O ratios of refractory oxide grains extracted from primitive meteorites suggest that they originated in low-mass red giant stars prior to the formation of the Solar System 4.6×10/sup9 ...
  • Gamma-ray source observations with the HAGAR telescope system at Hanle in the Himalayas 
    Britto, R. J; Acharya, B. S; Chitnis, V. R; Cowsik, R; Dorji, N; Duhan, S. K; Gothe, K. S; Kamath, P. U; Mahesh, P. K; Nagesh, B. K; Naidu, A; Parmar, N. K; Prabhu, T. P; Rao, S. K; Saha, L; Saleem, F; Saxena, A. K; Sharma, S. K; Shukla, A; Singh, B. B; Srinivasan, R; Srinivasulu, G; Sudersanan, P. V; Tsewang, D; Upadhya, S. S; Vishwanath, P. R (Societe Francaise d’Astronomie et dAstrophysique, 2009-11)
    We have observed Crab nebula using the recently commissioned wavefront sampling high alti- tude (4270 m) array, HAGAR, at Hanle in the Ladakh region of the Himalayas. Regular source observations have begun with the ...
  • High altitude gamma ray observatory at Hanle 
    Sripathi Acharya, B; Cowsik, R; Bhat, P. N; Chitnis, V. R; Vishwanath, P. R; Prabhu, T. P; Srinivasan, R (International Union of Pure and Applied Physics, 2003-07)
    We have carried out Monte Carlo simulations to study the nature of Cherenkov light pool generated by γ -ray and proton primaries for the altitude of Hanle(4515m amsl) in the Himalayas, the site of proposed HAGAR experiment. ...
  • High Resolution Multislit Spectroscopy of Solar Corona in two lines during the Total Solar Eclipse of Oct. 24, 1995 
    Singh, J; Gupta, S. S; Cowsik, R (Indian Institute of Astrophysics, Bangalore, 1997)
    Two coronal emission lines 5303 Armstrong (Fe XIV) and 6374 Armstrong (Fe X) corresponding to ionization temperatuess of 2 and 1 million degree kelvin respectively were used to obtain the high resolution coronal spectra ...
  • The Himalayan gamma ­ ray observatory at Hanle 
    Koul, R; Kaul, R. K; Mitra, A. K; Rannot, R. C; Acharya, B. S; Chitnis, V. R; Cowsik, R; Prabhu, T. P; Srinivasan, R; Srivatsan, R; Vishwanath, P (Tata Institute of Fundamental Research, 2005)
    A new gamma ray observatory comprising a large stereo imaging cherenkov telescope and an array of wave front sampling telescopes is being set up at the high altitude astronomical site at Hanle in the Ladakh region of ...
  • The implications of gamma-ray lines observed from the Orion complex 
    Cowsik, R; Friedlander, Michael. W (The American Astronomical Society, 1995-05)
    The observation of intense gamma-ray line emission from the Orion complex, attributed by Bloemen et al. to de-excitation of cosmic-ray carbon and oxygen nuclei, has important implications for emission from Orion in the ...
  • Implications of γ-ray lines observed from the orion complex. II 
    Cowsik, R; Friedlander, W. M (International Union of Pure and Applied Physics, 1995)
    The observation of intense gamma-ray line emission from the Orion complex, attributed by Bloemen et al. to de-excitation of cosmic-ray carbon and oxygen nuclei, has important, implications for emission from Orion in the ...
  • Indian Astronomical Observatory, Hanle 
    Cowsik, R; Srinivasan, R; Prabhu, T (Astronomical Society of the Pacific, 2002)
    The Indian Institute of Astrophysics (IIA) Bangalore has established the Indian Astronomical Observatory (IAO) at an altitude of 4500 m above mean sea level atop Mt. Saraswati, Hanle, Changthang Ladakh, India. The birth ...
  • Indian Institute of Astrophysics Annual Report: 1991-92 
    Cowsik, R (Indian Institute of Astrophysics, 1992)
  • Indian Institute of Astrophysics Annual Report: 1992-93 
    Cowsik, R (Indian Institute of Astrophysics, 1993)

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