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Browsing by Author "Bhattacharya, D"

Browsing by Author "Bhattacharya, D"

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  • Multiwavelength study of different flaring and low-activity states of blazar 4C+21.35 
    Bhattacharya, D; Krishna Mohana, A; Bhattacharyya, S; Bhatt, N; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-01)
    Blazars, a class of active galactic nuclei, emit over the entire accessible electromagnetic spectrum and modelling of their broad-band spectral energy distribution (SED) is the key to constrain the underlying emission ...
  • Neutron star physics in the square kilometre array era: an Indian perspective 
    Konar, S; Bagchi, Manjari; Bandyopadhyay, Debades; Banik, Sarmistha; Bhattacharya, D; Bhattacharyya, S; Gangadhara, R. T; Gopakumar, A; Gupta, Y; Joshi, B. C; Maan, Yogesh; Maitra, Chandreyee; Mukherjee, D; Pai, Archana; Paul, B; Ray, A; Sutaria, F. K (Indian Academy of Sciences, 2016-12)
    It is an exceptionally opportune time for astrophysics when a number of next-generation mega-instruments are poised to observe the Universe across the entire electromagnetic spectrum with unprecedented data quality. The ...
  • A Numerical Survey of Neutron Star Crustal Density Profiles 
    Datta, B; Thampan, A. V; Bhattacharya, D (Indian Academy of Sciences, 1995-12)
    An accurate numerical survey of the density profiles corresponding to the crusts of neutron stars for representative equation of state models is presented. This will find application in calculations of thermal and magnetic ...
  • Ohmic decay of magnetic flux expelled from neutron star interiors 
    Bhattacharya, D; Datta, B (Royal Astronomical Society, 1996-10)
    We study Ohmic diffusion of magnetic flux expelled from the superconducting core of a neutron star to its crust owing to spindown-induced field evolution. We find that Ohmic decay time-scales in the range 10^7.5-10^9 yr ...
  • The optical afterglow of the not so dark GRB 021211 
    Pandey, S. B; Anupama, G. C; Sagar, R; Bhattacharya, D; Castro-Tirado, A. J; Sahu, D. K; Parihar, P. S; Prabhu, T. P (The European Southern Observatory, 2003-09)
    We determine Johnson B,V and Cousins R,I photometric CCD magnitudes for the afterglow of GRB 021211 during the first night after the GRB trigger. The afterglow was very faint and would have been probably missed if no prompt ...
  • Optical and radio observations of the bright GRB 010222 afterglow: evidence for rapid synchrotron cooling ? 
    Sagar, R; Stalin, C. S; Bhattacharya, D; Pandey, S. B; Mohan, V; Castro-Tirado, A. J; Pramesh Rao, A; Trushkin, S. A; Nizhelskij, N. A; Bremer, M; Castro Ceron, J. M (Astronomical Society of India, 2001)
    We report photometric observations of the optical afterglow of GRB 010222 in V, R and I passbands carried out between 22-27 February 2001 at Nainital. We determine the CCD Johnson BV and Cousins RI photometric magnitudes ...
  • Optical follow up of the GRB 990123 sources from UPSO, Naini Tal 
    Sagar, R; Pandey, A. K; Mohan, V; Yadav, R. K. S; Nilakshi; Bhattacharya, D; Castro-Tirado, A. J (Astronomical Society of India, 1999)
    The CCD magnitudes in Johnson $BV$ and Cousins $R$ photometric passbands are determined for the optical transient of GRB 990123. These observations have been taken approximately 12 hours after trigger of the gamma-ray ...
  • Optical follow-up of GRB afterglows from UPSO, Naini Tal 
    Pandey, S. B; Sagar, R; Mohan, V; Pandey, A. K; Bhattacharya, D; Castro-Tirado, A. J (Astronomical Society of India, 2001)
    Successful optical photometric observations of five GRB afterglows namely GRB 990123, GRB 991208, GRB 991216, GRB 000301c and GRB 000926 have been carried out from State Observatory Naini Tal till 2000. The results and ...
  • Optical observations and multiband modelling of the afterglow of GRB041006 : Evidence of a hard electron energy spectrum 
    Misra, K; Resmi, L; Pandey, S. B; Bhattacharya, D; Sagar, R (Astronomical Society of India, 2005-12)
    We present the CCD Cousins R band photometric observations of the afterglow of GRB 041006. The multiband afterglow evolution is modelled using an underlying `hard' electron energy spectrum with a p1 ~ 1.3. The burst appears ...
  • Optical observations of GRB 060124 afterglow: a case for an injection break 
    Misra, K; Bhattacharya, D; Sahu, D. K; Sagar, R; Anupama, G. C; Castro-Tirado, A. J; Guziy, S. S; Bhatt, B. C (EDP Sciences, 2007-03)
    Aims.We present broad band optical afterglow observations of a long duration GRB 060124 using the 1.04-m Sampurnanand Telescope at ARIES, Nainital and the 2.01-m HCT at IAO, Hanle, including the earliest ground-based ...
  • Optical observations of the bright long duration peculiar GRB 021004 afterglow. 
    Pandey, S. B; Sahu, D. K; Resmi, L; Sagar, R; Anupama, G. C; Bhattacharya, D; Mohan, V; Prabhu, T. P; Bhatt, B. C; Pandey, J. C; Parihar, P. S; Castro-Tirado, A. J (Astronomical Society of India, 2003)
    The CCD magnitudes in Johnson B,V and Cousins R and I photometric passbands are determined for the bright long duration GRB 021004 afterglow from 2002 October 4 to 16 starting ~ 3 hours after the γ - ray burst. Light curves ...
  • Probing into emission mechanisms of GRB 190530A using time-resolved spectra and polarization studies: synchrotron origin? 
    Gupta, Rahul; Gupta, S; Chattopadhyay, T; Lipunov, V; Castro-Tirado, A. J; Bhattacharya, D; Pandey, S. B; Oates, S. R; Kumar, Amit; Hu, Y-D; Valeev, A. F; Minaev, P. Yu; Kumar, H; Vinko, J; Dimple; Sharma, V; Aryan, A; Castellon, A; Gabovich, A; Moskvitin, A; Ordasi, A; Pal, A; Pozanenko, A; Zhang, B-B; Kumar, B; Svinkin, D; Saraogi, D; Vlasenko, D; Fernandez-Garcia, E; Gorbovskoy, E; Anupama, G. C; Misra, K; Sarneczky, K; Kriskovics, L; Castro-Tirado, M. A; Caballero-Garcia, M. D; Tiurina, N; Balanutsa, P; Lopez, R. R; Sanchez-Ramirez, R; Szakats, R; Belkin, S; Guziy, S; Iyyani, S; Tiwari, S. N; Vadawale, Santosh V; Sun, T; Bhalerao, V; Kornilov, V; Sokolov, V. V (Oxford University Press on behalf of Royal Astronomical Society, 2022-04)
    Multipulsed GRB 190530A, detected by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope onboard Fermi, is the sixth most fluent GBM burst detected so far. This paper presents the timing, spectral, and polarimetric ...
  • Radio, millimeter and optical monitoring of GRB 030329 afterglow: constraining the double jet model 
    Resmi, L; Ishwara-Chandra, C. H; Castro-Tirado, A. J; Bhattacharya, D; Rao, A. P; Bremer, M; Pandey, S. B; Sahu, D. K; Bhatt, B. C; Sagar, R; Anupama, G. C; Subramaniam, A; Lundgren, A; Gorosabel, J; Guziy, S; de Ugarte Postigo, A; Castro Cerón, J. M; Wiklind, T (EDP Sciences, 2005-09)
    We present radio, millimeter and optical observations of the afterglow of GRB 030329. $UBVR_{\rm C}I_{\rm C}$ photometry is presented for a period of 3 h to 34 days after the burst. Radio monitoring at 1280 MHz has been ...
  • SN 2002ap, the Hypernova of Class Ic 
    Pandey, S. B; Sahu, D. K; Anupama, G. C; Bhattacharya, D; Sagar, R (Astronomical Society of India, 2003)
    The supernova SN 2002ap was discovered in the outer regions of the nearby spiral M74 on January 29.4 UT. Early photometric and spectroscopic observations indicate the supernova belongs to the class of Ic hypernova. Late ...
  • Supernova 1987A - A review 
    Bhattacharya, D (Astronomical Society of Indian, 1988)
    Supernova 1987A, the first supernova since the time of Kepler to reach naked-eye visibility, was discovered on February 24, 1987, in the Large Magellanic Cloud. This has naturally been of great interest to astronomers. The ...

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