IIA Institutional Repository: Recent submissions

  • X-ray spectrum of NGC 3783 - Detection of soft excess and an emission line 
    Ghosh, K. K; Soundararajaperumal, S; Kalai Selvi, M; Sivarani, T (EDP Sciences, 1992-02)
    Results of the X-ray (0.1-10 keV) spectral analysis of the Seyfert I galaxy, NGC 3783, which was observed with EXOSAT on three epochs between 1983 and 1985, are presented here. No low energy absorption, intrinsic to the ...
  • Simulation Studies for Optimizing the Trigger Field of View of the TACTIC Imaging Element 
    Koul, M. K; Sapru, M. L (Astronomical Society of India, 2003)
    Simulation studies, for the Imaging Camera of the TACTIC -ray telescope have been carried out to optimize its trigger field of view for a point -ray source. The results indicate that a trigger field of 9 x 9 pixels should ...
  • Artificial Neural Network-based Image-cleaning Method for Atmospheric Cerenkov Imaging Telescopes 
    Dhar, V. K; Tickoo, A. K; Kaul, M. K; Kaul, C. L; Rannot, R. C; Yadav, K. K; Dubey, B. P; Koul, R (Astronomical Society of India, 2003)
    A novel image-cleaning method, based on the utilization of Artificial Neural Network (ANN) is shown here to `correctly' select more pixels in a Cerenkov image than in the conventional approach.
  • The Mauritius Radiotelescope 
    Golap, K; Issur, N. H; Somanah, R; Dodson, R; Modgekar, M; Sachdev, S; Shankar, N. Udaya; Sastry, Ch. V (Springer Netherlands, 1995-06)
    The Mauritius Radiotelescope (MRT) is a T-shaped array of helical antennas with a 2048 m EW arm and a 890 m South arm. The primary objective of the telescope is to produce a sky survey in the declination zone -15° to -65° ...
  • Probable binary open star clusters in the Galaxy. 
    Subramaniam, A; Gorti, U; Sagar, R; Bhatt, H. C (EDP Science, 1995-10)
    The existence of double/binary clusters in the Magellanic Clouds is fairly well established, whereas only one such pair, h + χ Persei, is known in the Galaxy. From the catalogues of open clusters of the Galaxy, we have ...
  • A High Energy Photon Detector Simulation System 
    Sinha, S (Astronomical Society of India, 2003)
    A high energy photon detector simulation software based on detailed Monte Carlo method starting from first principles is under development. The current status of this endeavour and some of the results obtained recently ...
  • Image Reconstruction for a Continuously Rotating Coded Mask Camera 
    Shankar, B. T. R; Bhattacharya, D (Astronomical Society of India, 2003)
    We discuss a method for reconstructing the image for Scanning Sky Monitor which is a continuously rotating X-ray coded mask camera aboard the Indian astronomical satellite, ASTROSAT.
  • Galaxy dynamics with small computers: Some results on tidal interactions. 
    Kochhar, R. K; Namboodiri, P. M. S (Springer Netherlands, 1995-06)
    Numerical simulations with a small computer have been performed to investigate the tidal influence of a larger galaxy on a smaller companion. A criterion is developed for disruption of the satellite galaxy. The behaviour ...
  • A Dynamic Sky Simulation for the Scanning Sky Monitor on ASTROSAT 
    Mishra, S. D; Bhattacharya, D (Astronomical Society of India, 2003)
    We have developed a dynamic sky simulation software for the visualization of the operation of the Scanning Sky Monitor cameras. This software can be used for the background modelling of the cameras and the refinement of ...
  • Scanning Sky Monitor (SSM) on ASTROSAT- A Status Report 
    Seetha, S; The SSM team of ASTROSAT (Astronomical Society of India, 2003)
  • The synthesis of Al-26 during combined hydrogen and helium-burning reactions 
    Goswami, A; Ramadurai, S; Duorah, H. L (Springer Netherlands, 1992-02)
    The synthesis of Al-26 during combined hydrogen and helium-burning processes in high temperature and density conditions is studied. The possible sites for these processes are believed to be the neutron star surfaces where ...
  • Control and Operation of SOXS High Energy Detector 
    Janawlekar, S. B; Malkar, J. P; Rao, A. R; Vadawale, S. V; Vahia, M. N; Umapathy, C. N (2003)
    The control and operation of the SOXS High Energy Detector (HED) experiment is done using a micro-processor based data handling system (the GSAT-2 SOXS High Energy Electronics package - GXHE). The GXHE system is used for ...
  • Distribution of ionized gas in X-ray bright early-type galaxies. 
    Singh, K. P; Bhat, P. N; Prabhu, T. P; Kembhavi, A. K (Springer, 1995-10)
    We report imaging observations of Hα+[N II] nebulosities in seven early type galaxies viz., NGC 1399, NGC 1600, NGC 2563, NGC 4203, NGC 4636, NGC 4753 and NGC 5044. These are primarily X-ray bright galaxies which are the ...
  • The Ultra Violet Imaging Telescope: Mechanical Design 
    Pati, A. K; Mahesh, P. K; Nagabhushana, S; Subramanian, V. K (Astronomical Society of India, 2003)
    The Ultra Violet Imaging Telescope (UVIT) is one of the major scientific instruments on the proposed ASTROSAT mission of the Indian Space Research Organisation. The design of a telescope to meet the scientific requirements ...
  • High Resolution Spectroscopy with Submillimeter-Wave 
    Kumar, V; Dave, H (Astronomical Society of India, 2003)
    In order to explain the characteristic features of planetary atmosphere, detection and precise measurements of environmentally important gases such as CO, CIO, No becomes necessary. Since most of the polyatomic molecules ...
  • On the Large-Scale Diffuse Magnetic Field of the Sun 
    Dikpati, M; Choudhuri, A. R (Springer, 1995-10)
    Although the sunspots migrate towards the equator, the large-scale weak diffuse magnetic fields of the Sun migrate poleward with the solar cycle, the polar field reversing at the time of the sunspot maxima. We apply the ...
  • X-ray continuum with an iron emission line from the radio-quiet quasar PHL 909 
    Ghosh, K. K; Soundararajaperumal, S (University of Chicago Press, 1992-04)
    Results of the spectral analysis of the X-ray (0.1-10 keV) spectrum of the radio-quiet quasar, PHL 909, are presented. A spectrum of this quasar, which was observed on 1984/349, was obtained from the Exosat archives. ...
  • The role of Compton and Raman scattering in the quasar continuum 
    Gangadhara, R. T; Krishan, V (Blackwell Publishing, 1992-05)
    There are three ways in which an electromagnetic wave can undergo scattering in a plasma: (1) when the scattering of radiation occurs by a single electron, it is called Compton Scattering; (2) if it occurs by a longitudinal ...
  • Global modes constituting the solar magnetic cycle. II - Phases, 'geometrical eigenmodes', and coupling of field behaviour in different latitudes 
    Gokhale, M. H; Javaraiah, J (Springer Netherlands, 1992-04)
    We show that the axisymmetric odd degree SHF modes of 21.4-yr periodicity and degrees l le 29 in the solar magnetic field (as inferred from sunspot data during 1874–1976), are at least approximately stationary. Among the ...
  • Magnetic shear in flaring regions. I - Quantitative evaluation of the change in shear 
    Sivaraman, K. R; Rausaria, R. R; Aleem, S. M (Springer Netherlands, 1992-04)
    We have evaluated the shear angle of the neutral line of the non-potential magnetic field for one or two days prior to and after the flare event for 10 cases. We have used the Hagr filament positions to evaluate the shear ...

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