IIA Institutional Repository: Recent submissions

  • Wide Field CCD Photometry of the Young Open Cluster NGC 663 
    Pandey, A. K; Upadhyay, K; Ogura, K; Sagar, R (Astronomical Society of India, 2003)
    A deep and wide field CCD photometry of the young open cluster NGC 663 has been carried out. We report preliminary results of our investigations, specifically the determination of the cluster mass function which is found ...
  • Large-Area Wide Angle (LAWA) cerenkov detector for MYSTIQUE array 
    Kamath, K; Bhattacharyya, S; Dhar, V. K; Darzi, M. A; Kaul, S. R; Kaul, R. K; Koul, R; Sahayanathan, S; Tickoo, A. K; Wani, A. M; Bhat, C. L (Astronomical Society of India, 2002)
    An ultra-sensitive, multidetector wide angle atmospheric Cerenkov telescope array is being set up at Mt. Abu for cosnic gamma-ray studies in tens of TeV energy region. The design features of the Cerenkov light detector, ...
  • Spot size of 17m-diameter MACE reflector in presence of surface inaccuracies 
    Koul, D. K; Koul, M. K; Tickoo, A. K; Bhat, C. L (Astronomical Society of India, 2002)
    The MACE (for Major Atmospheric Cerenkov Experiment), an imaging cerenkov telescope for gamma-ray astronomy investigations in the sub-TeV energy bracket, plans to use a 17 m-diameter high quality reflecter mounted with a ...
  • The Effect of Non-thermal Protons on the High Energy Spectra of Black Hole Binaries 
    Bhattacharyya, S; Bhatt, N; Misra, R; Kaul, C. L (Astronomical Society of India, 2003)
    We investigate here the effect on the emitted spectrum of a black hole binary due to the presence of accelerated protons in the inner region of the accretion disk. Our study shows that e-e+ pairs and high energy -rays ...
  • Pulsating Soft Components in the Accreting X-ray Pulsars LMC X-4 and SMC X-1 
    Naik, S; Paul, B (Astronomical Society of India, 2003)
    We report here spectral study of two accreting binary X-ray pulsars LMC X-4 and SMC X1 made with the Beppo-SAX observatory. The energy spectrum of both the pulsars in 0.1-10.0 keV band can be described by a model consisting ...
  • 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 ...
  • Relativistic unitary coupled cluster theory and applications 
    Sur, C; Chaudhuri, R. K; Sahoo, B. K; Das, B. P; Mukherjee, D (Institute of Physics, 2008-03)
    We present the formulation and application of relativistic unitary coupled cluster theory to atomic properties. The remarkable features of this theory are highlighted, and it is used to calculate the lifetimes of 5d2D3/2 ...
  • Optimum image parameter ranges for TACTIC imaging elements : guidance from simulations 
    Koul, M. K; Charagi, S. K; Rannot, R. C; Sapru, M. L; Bhat, C. L (Astronomical Society of India, 2002)
    In this paper, we present some results on the performance characteristics of the TACTIC Imaging Element (IE) as predicted by extensive simulation studies. The main features studied are the optimum image parameter ranges ...
  • Novel image and non-image parameters for efficient characterisation of atmospheric Cerenkov images 
    Razdan, A; Haungs, A; Rebel, H; Bhat, C. L (Astronomical Society of India, 2002)
    We make a comparative study of the classification potential of various image and non-image parameters which are measurable with the TACTIC array focal plane instrumentation. The image parameters include conventional Hillas ...
  • Longitudinal shower development and its signature at observation level 
    Chitnis, V. R; Bhat, P. N (Astronomical Society of India, 2002)
    From a study of Cverenkov photon arrival times at various core distances at the observation level it has already been established that the photon front is well fitted with a spherical surface traveling at the speed of light ...
  • Recent onset of an outburst in mu centauri 
    Ghosh, K. K; Velu, C; Kuppuswamy, K; Jaykumar, K; Rosario, M. J (Konkoly Observatory, 1987-08)
  • Estimation of vital shower parameters in wavefront sampling technique 
    Chitnis, V. R; Bhat, P. N (Astronomical Society of India, 2002)
    Wavefront sampling experiments record arrival times of Cverenkov photons with high precision at various locations in Cverenkov pool using a distributed array of telescopes. It was shown earlier that this photon front can ...
  • Gamma-hadron separation using Cverenkov photon density fluctuations 
    Chitnis, V. R; Bhat, P. N (Astronomical Society of India, 2002)
    In atmospheric Cverenkov technique gamma-rays are detected against abundant background produced by hadronic showers. In order to improve signal to noise ratio of the experiment, it is necessary to reject a significant ...
  • Gamma ray and hadron generated Cverenkov photon spectra at various observation altitudes 
    Rahman, M. A; Bhat, P. N; Acharya, B. S; Chitnis, V. R; Majumdar, P; Vishwanath, P. R (Astronomical Society of India, 2002)
    We have studied the propagation of Cverenkov photons generated by Very High Energy gamma-rays and hadrons in the atmosphere. Photon production height distributions derived from semi-empirical methods agree with those ...
  • Cosmic ray mass composition through Cerenkov technique - a feasibility study 
    Bhat, C. K; Kaul, R. K; Sapru, M. L; Bhat, C. L (Astronomical Society of India, 2002)
    Detailed Monte Carlo simulations of atmospheric Cerenkov events, recorded by the 349 - pixel imaging camera of the TACTIC Imaging Cerenkov Telescope array at Mt. Abu, Rajasthan, have been carried out to study the possibility ...
  • Understanding the behavior of energy X-rays from the black hole candidate GRS 1915+105 
    Nandi, A; Chakrabarti, S. K (Astronomical Society of India, 2002)
    Black Hole candidate GRS 1915+105 shows a very interesting behaviour at high energy X-rays. For instance, it shows quasi-Periodic Oscillations (QPO) only at high energies. Also the spectral slopes at high energies vary and ...
  • Analytical study of standing shocks around black hole 
    Das, S; Chakrabarti, S. K (Astronomical Society of India, 2002)
    Shocks from around black holes as the matter slows down by centifugal barrier. At the shocks, kinetic energy is converted into thermal energy and hard-X rays, outflows etc. are produced which are observed. We compute the ...
  • X-ray observations of the Seyfert 1 galaxy MCG 2-58-22 
    Ghosh, K. K; Soundararajaperumal, S (University of Chicago Press, 1992-10)
    Results of the detailed X-ray (0.1-10 keV) spectral analysis of the Seyfert 1 galaxy, MGC 2-58-22, are presented based on the Exosat observations on 1984 November 16-26. X-ray spectra of this source were obtained from the ...
  • X-ray spectra of Seyfert galaxies 
    Ghosh, K. K; Soundararajaperumal, S (Blackwell Publishing, 1992-11)
    A spectra analysis of eight Seyfert galaxies shows that while seven have soft excesses in their spectra, with no low-energy absorption, ESO 140-G43 exhibits low energy absorption, and may have weak soft excess that is ...
  • On the role of reverse current on the hard X-ray production in solar flares and time-lags between high- and low-energy photons 
    Bakaya, R; Chasti, S. A; Rausaria, R. R (Springer Netherlands, 1992-09)
    The evolution of energy and angular distributions of electrons has been studied accounting for the reverse current effect by combining analytically treated small angle multiple scatterings with large angle Monte-Carlo ...

Search DSpace

Browse

My Account