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Browsing by Author "Vishwanath, P. R"

Browsing by Author "Vishwanath, P. R"

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  • A mini ACT experiment at low and high altitudes 
    Vishwanath, P. R; Acharya, B. S; Bhat, P. N; Chitnis, V. R (Tata Institute of Fundamental Research, 2005)
    A simple experimental apparatus was used to measure rate of cosmic ray events due to Atmospheric Cerenkov Radiation at two mountain altitude sites with the height difference of 3.5 km. The event rates at Hanle (altitude ...
  • Multi-frequency, multi-epoch study of MrK 501: hints for a two-component nature of the emission 
    Shukla, A; Chitnis, V. R; Singh, B. B; Acharya, B. S; Anupama, G. C; Bhattacharjee, P; Britto, R. J; Mannheim, K; Prabhu, T. P; Saha, L; Vishwanath, P. R (IOP Publishing, 2015-01-01)
    Since the detection of very high energy (VHE) γ -rays from Mrk 501, its broadband emission of radiation was mostly and quite effectively modeled using the one zone emission scenario. However, broadband spectral and flux ...
  • Multiwavelength study of the TeV blazar Mrk 421 during a giant flare 
    Shukla, A; Chitnis, V. R; Vishwanath, P. R; Acharya, B. S; Anupama, G. C; Bhattacharjee, P; Britto, R. J; Prabhu, T. P; Saha, L; Singh, B. B (EDP Sciences, 2012-05)
    Aims. The nearby (z = 0.031) TeV blazar Mrk 421 was reported to be in a high state of flux activity since November, 2009. We aim to investigate possible changes in the physical parameters of Mrk 421 during its high state ...
  • Observations of AGNs using PACT 
    Bose, D; Chitnis, V. R; Vishwanath, P. R; Majumdar, P; Rahman, M. A; Singh, B. B; Gupta, A. C; Acharya, B. S (Springer Netherlands, 2007-06)
    We report our observations on 4 AGNs viz, Mkn 421, Mkn 501, 1ES1426+428 and ON231 belonging to a sub-class called blazars. The observations were carried out using the Pachmarhi Array of Cherenkov Telescopes and span about ...
  • Observations with the High Altitude GAmma Ray (HAGAR) telescope array in the Indian Himalayas 
    Britto, R. J; Acharya, B. S; Anupama, G. C; Bhatt, N; Bhattacharjee, P; Bhattacharya, S. S; Chitnis, V. R; Cowsik, R; Dorji, N; Duhan, S. K; Gothe, K. S; Kamath, P. U; Koul, R; Mahesh, P. K; Mitra, A; Nagesh, B. K; Parmar, N. K; Prabhu, T. P; Rannot, R. C; 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; Tickoo, A. K; Tsewang, D; Upadhya, S; Vishwanath, P. R; Yadav, K. K (French Society of Astronomy and Astrophysics, 2010-12)
    For several decades, it was thought that astrophysical sources emit high energy photons within the energy range of the gamma-ray region of the lectromagnetic spectrum also. These photons originate from interactions of high ...
  • Observations with the High Altitude GAmma-Ray (HAGAR) telescope array in the Indian Himalayas 
    Britto, R. J; Acharya, B. S; Anupama, G. C; Bhatt, N; Bhattacharjee, P; Bhattacharya, S; Chitnis, V. R; Cowsik, R; Dorji, N; Duhan, S. K; Gothe, K. S; Kamath, P. U; Koul, R; Manoharan, J; Mahesh, P. K; Mitra, A; Nagesh, B. K; Parmar, N. K; Prabhu, T. P; Rannot, R. C; 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; Tickoo, A. K; Tsewang, D; Upadhya, S. S; Vishwanath, P. R; Yadav, K. K (Copernicus Publications, 2011-11)
    The High Altitude GAmma-Ray (HAGAR) array is a wavefront sampling array of 7 telescopes, set-up at Hanle, at 4270 m amsl, in the Ladakh region of the Himalayas (Northern India). It constitutes the first phase of the HImalayan ...
  • PACT results on very high energy g-ray emission from CRAB pulsar 
    Sripathi Acharya, B; Vishwanath, P. R; Bhat, P. N; Chitnis, V. R; Majumdar, P; Rahman, M. A; Singh, B. B (International Union of Pure and Applied Physics, 2003-07)
    The data taken on the Crab pulsar by the recently commissioned array of ˇ Cerenkov telescopes at Pachmarhi using the wave front sampling technique have been analyzed. The phasograms show significant excess of events at the ...
  • Performance studies of the PACT experiment 
    Vishwanath, P. R; Acharya, B. S; Bhat, P. N; Chitnis, V. R; Majumdar, P; Rahman, M. A; Singh, B. B (Astronomical Society of India, 2002)
    Monte Carlo calculations have been done to understand various characteristics like the energy threshold, collection area etc of the recently commissioned PACT. The energy threshold of the array for gamma rays is found to ...
  • Pointing of HAGAR telescope mirrors 
    Gothe, K. S; Prabhu, T. P; Vishwanath, P. R; Acharya, B. S; Srinivasan, R; Chitnis, V. R; Kamath, P. U; Srinivasulu, G; Saleem, F; Kemkar, P. M. M; Mahesh, P. K; Gabriel, F; Manoharan, J; Dorji, N; Dorjai, T; Angchuk, D; D'souza, A. I; Duhan, S. K; Nagesh, B. K; Rao, S. K; Sharma, S. K; Singh, B. B; Sudersanan, P. V; Thsering, M. T; Upadhya, S. S; Anupama, G. C; Britto, R. J; Cowsik, R; Saha, L; Shukla, A (Springer, 2013-04)
    An array of seven atmospheric Cherenkov telescopes was commissioned at a high altitude site in Hanle in the Ladakh region of the Himalayas. The array called HAGAR has been designed to observe celestial γ-rays of energy ...
  • Possible bursts of TeV gamma rays in PACT from MKN 421 in April 2004 
    Vishwanath, P. R (International Union of Pure and Applied Physics, 2005)
  • A possible high altitude high energy gamma ray observatory in India 
    Cowsik, R; Bhat, P. N; Chitnis, V. R; Acharya, B. S; Vishwanath, P. R (Copernicus Gesellschaft, 2001-08)
    Recently an Indian Astronomical Observatory has been set up at Hanle (32° 46 4 6 N , 78° 57 5 1 E , 4515m amsl) situated in the high altitude cold desert in the Himalayas. The Observatory has 2-m aperture optical-infrared ...
  • Preliminary results on the flux of TeV g-rays from crab system obtained with the PACT at Pachmarhi 
    Sripathi Acharya, B; Bhat, P. N; Chitnis, V. R; Majumdar, P; Rahman, M. A; Singh, B. B; Vishwanath, P. R (International Union of Pure and Applied Physics, 2003-07)
    We have observed the Crab system (Nebula and Pulsar) and the corresponding background regions during many clear nights in the years 1999-2002 ˇ using the atmospheric Cerenkov array at Pachmarhi, PACT. Preliminary results ...
  • A review of observational results on very high energy gamma-ray emission from pulsars 
    Vishwanath, P. R (Astronomical Society of India, 2002)
    Radio pulsars have played a very important part in the growth of VHE (Very High Energy) gamma-ray astronomy. Apart from their ability to accelerate particles to very high energies, the modest sensitivity of the first ...
  • Search for TeV gamma-rays from Geminga pulsar 
    Singh, B. B; Chitnis, V. R; Bose, D; Rahman, M. A; Upadhya, S. S; Gothe, K. S; Nagesh, B. K; Purohit, P. N; Rao, S. K; Rao, K. K; Sharma, S. K; Sudersan, P. V; Venkateshmurthy, B. L; Vishwanath, P. R; Acharya, B. S (Elsevier, 2009-09)
    We present the results of observation of the Geminga pulsar carried out in the TeV energy band during the 6 year period spanning 2000–2006 using the Pachmarhi Array of Cherenkov Telescopes (PACT). A long stretch of data, ...
  • Status of HAGAR, the high altitude gamma ray observatory at Hanle 
    Chitnis, V. R; Acharya, B. S; Bhat, P. N; Cowsik, R; Prabhu, T. P; Srinivasan, R; Srivatsan, R; Vishwanath, P. R (Tata Institute of Fundamental Research, 2005)
    A 7 telescope array is planned to be constructed at Hanle in the Himalayas at an altitude of about 4200m above mean sea level for detecting celestial gamma-rays. The atmospheric Cerenkov light pool created by the ...
  • Status of the Himalayan Gamma-Ray Observatory (HIGRO) and observation with HAGAR at very high energies 
    Britto, R. J; Acharya, B. S; Anupama, G. C; Bhatt, N; Bhattacharjee, P; Bhattacharya, S; Chitnis, V. R; Cowsik, R; Dorji, N; Duhan, S. K; Gothe, K. S; Kamath, P. U; Koul, R; Mahesh, P. K; Manoharan, J; Mitra, A; Nagesh, B. K; Parmar, N. K; Prabhu, T. P; Rannot, R. C; 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; Tickoo, A. K; Tsewang, D; Upadhya, S. S; Vishwanath, P. R; Yadav, K. K (French Society of Astronomy and Astrophysics, 2011-12)
    High Altitude GAmma Ray (HAGAR) telescope array, which is the first stage of HImalayan Gamma Ray Observatory (HIGRO), has been successfully installed at Hanle in Himalayas and has been collecting science data since September, ...
  • A study of the performance parameters of the High Altitude Gamma Ray (HAGAR) telescope system at Ladakh in India 
    Saha, L; Chitnis, V. R; Vishwanath, P. R; Kale, S; Shukla, A; Acharya, B. S; Anupama, G. C; Bhattacharjee, P; Britto, R. J; Prabhu, T. P; Singh, B. B (Elsevier Science B.V., 2013-02)
    We present results of Monte Carlo simulations for the High Altitude Gamma Ray (HAGAR) telescope array which detects very high energy gamma rays from astronomical sources. This telescope array, located at Hanle at an altitude ...
  • TeV Gamma-ray flares from Mkn 421 detected by the pachmarhi array of Cverenkov Telescopes 
    Bhat, P. N; Acharya, B. S; Chitnis, V. R; Majumdar, P; Rahman, M. A; Singh, B. B; Vishwanath, P. R (Astronomical Society of India, 2002)
    Pachmarhi Array of Cverenkov Telescopes (PACT), based on wavefront sampling technique, has been used for detecting TeV gamma rays from galactic and extra-galactic ?-ray sources. The Blaar, Mkn 421 was one such extra-galactic ...
  • Towards new analysis of Gamma-Ray sources at HImalayan Gamma-Ray Observatory (HIGRO) in northern India 
    Britto, R. J; Acharya, B. S; Anupama, G. C; Bhatt, N; Bhattacharjee, P; Bhattacharya, S; Chitnis, V. R; Cowsik, R; Dorji, N; Duhan, S. K; Gothe, K. S; Kamath, P. U; Koul, R; Mahesh, P. K; Mitra, A; Nagesh, B. K; Parmar, N. K; Prabhu, T. P; Rannot, R. C; 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; Tickoo, A. K; Tsewang, D; Upadhya, S. S; Vishwanath, P. R; Yadav, K. K (French Society of Astronomy and Astrophysics, 2010-12)
    The High Altitude GAmma-Ray (HAGAR) array is a wavefront sampling array of 7 telescopes, set-up at Hanle, at 4270 m a.s.l., in the Ladakh region of the Himalayas (North India). It constitutes the first phase of the HImalayan ...
  • Very high energy gamma rays from geminga pulsar 
    Vishwanath, P. R; Sripathi Acharya, B; Bhat, P. N; Chitnis, V. R (International Union of Pure and Applied Physics, 2005)

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