IIA Institutional Repository: Recent submissions

  • Limited Seeing Measurements at Mount Abu Infrared Observatory 
    Ashok, N. M; Banerjee, D. P. K (Astronomical Society of India, 2002-12)
    Measurements of atmospheric seeing for the Mount Abu Infrared Observatory, Gurusikhar are presented. Observations made with a differential image motion monitor, between 6 December 1999 to 28 April 2000, give an ...
  • Techniques for Achieving Higher Spatial Resolution 
    Sridharan, R (Astronomical Society of India, 2002-09)
    The application of speckle and interferometric techniques for imagmg small scale solar features is studIed In detail. A computer program(speckle code) was dt!v(-joped to analyze the speckle data. The capability of the ...
  • Scattering of light by periodic structure with randomness 
    Chatterjee, S; Vani, V. C (Astronomical Society of India, 2002-09)
  • Imaging with the Scanning Sky Monitor on ASTROSAT 
    Bhattacharya, D; Shankar, B. T. R (Astronomical Society of India, 2002-09)
    This paper describes the status of the development of software for coded mask imaging with the Scanning Sky Monitor aboard the proposed Indian multi wavelength astronomy satellite ASTROSAT.
  • Scanning Sky Monitor (SSM) on ASTROSAT - A status report 
    Seetha, S (Astronomical Society of India, 2002-09)
    The scanning sky monitor (SSM) on the ASTROSAT is an instrument to be used for detecting and locating new x-ray transients and to study the long term behavior of the known bright x-ray sources in the celestial sphere. ...
  • First light observations with TIFR near-infrared camera 
    Ojha, D. K; Ghosh, S. K; Verma, R. P; Chakraborti, A; Anandarao, B. G (Astronomical Society of India, 2002-09)
    The TIFR near-infrared camera (TmCAM) is based on the SBRC InSb focal plane array (58x62 pixels) sensitive between 1-5 pm. TIRCAM had its first engineering run at Gurusikhar 1.2 meter PRL telescope at Mount Abu during ...
  • Optical and radio variability of the BL Lacertae object AO 0235+16: A possible 5-6 year periodicity 
    Raiteri, C. M; Villata, M; Aller, H. D; Aller, M. F; Heidt, J; Kurtanidze, O. M; Lanteri, L; Maesano, M; Massaro, E; Montagni, F; Nesci, R.; Nilsson, K; Nikolashvili, M. G; Nurmi, P; Ostorero, L; Pursimo, T; Rekola, R; Sillanpää, A; Takalo, L. O; Teräsranta, H; Tosti, G; Balonek, T. J; Feldt, M; Heines, A; Heisler, C; Hu, J.; Kidger, M; Mattox, J. R; McGrath, E. J; Pati, A. K; Robb, R; Sadun, A. C; Shastri, P; Wagner, S. J; Wei, J; Wu, X (E D P Sciences, 2001-10)
    The BL Lacertae object AO 0235+16 is well known for its extreme optical and radio variability. New optical and radio data have been collected in the last four years by a wide international collaboration, which confirm the ...
  • Why Does the Sun Have Kilogauss Magnetic Fields? 
    Hasan, S. S; van Ballegooijen, A. A (Astronomical Society of the Pacific, 1998)
    Magnetic fields in the solar photosphere are concentrated in flux tubes with kilogauss field strength surrounded by nearly field-free plasma. Observations show that the flux tubes are located in convective downdrafts where ...
  • Longitudinal dependence of equatorial F region vertical plasma drifts in the dusk sector 
    Sastri, J. H (American Geophysical Union, 1996-02)
    The effect of solar activity on the postsunset peak of F region vertical plasma drift at Kodaikanal (77°28'E, dip 3°N) is determined as a function of season and for two levels of magnetic activity using extensive HF phase ...
  • A multicolour CCD photometric and mass function study of the distant southern open star clusters NGC 3105, NGC 3603, Melotte 105, Hogg 15, NGC 4815, Pismis 20 and NGC 6253 
    Sagar, R; Munari, U; de Boer, K. S (Royal Astronomical Society, 2001-10)
    We derive cluster parameters and mass functions from new UBVRI CCD photometric observations of ~3500 stars reaching down to V~20mag for the distant southern open star clusters NGC 3105, NGC 3603, Melotte 105, Hogg 15, NGC ...
  • CA II K Line Profile of the Truly Quiet Sun 
    Sivaraman, K. R; Gupta, S. S; Kariyappa, R (Kluwer Academic Publishers, 1996-01)
    While evaluating the chromospheric variability (solar cycle related or any other) using the Ca II K line (λ3933.684 Å) as an indicator, an essential prerequisite is the knowledge of the profile of a truly quiet Sun in the ...
  • Occurrence of Metric Noise Storms and the Onset of Coronal Mass Ejections in the Solar Atmosphere 
    Ramesh, R; Sundaram, G. A. S (Springer, 2001-05)
    We performed a statistical study of the metric noise-storm continuum sources (located close to/off the solar limb, and whose start time are precisely known) observed during the period January 1997 - June 1998. The main ...
  • Probing Dust in the Atmosphere of Brown Dwarfs through Polarization 
    Sengupta, S; Krishan, V (The American Astronomical Society, 2001-11)
    The theoretical analysis and observational evidence indicate that a brown dwarf with an effective temperature greater than 1300 K would have a dust cloud in its atmosphere. In this Letter, we show that dust scattering ...
  • Formation of a proto-quasar from accretion flows in a halo 
    Mangalam, A (E D P Sciences, 2001-12)
    We present a detailed model for the formation of massive objects at the centers of galaxies. The effects of supernovae heating and the conditions of gas loss are revisited. The escape time of the gas is compared with the ...
  • A comprehensive study of the rich open star cluster NGC 2099 based on deep BVI CCD observations 
    Nilakshi; Sagar, R (E D P Sciences, 2002-01)
    The CCD observations of the rich open star cluster NGC 2099 and its surrounding field region have been carried out up to a limiting magnitude of V ~ 22 mag in B, V and I passbands for the first time. A total of ~ 12 000 ...
  • Ring Diagram Analysis of the Characteristics of Solar Oscillation Modes in Active Regions 
    Rajaguru, S. P; Basu, S; Antia, H. M (The American Astronomical Society, 2001-12)
    The presence of intense magnetic fields in and around sunspots is expected to modify solar structure and oscillation frequencies. Applying the ring diagram technique to data from the Michelson Doppler Imager on board the ...
  • Non-uniform extinction in young open star clusters 
    Yadav, R. K. S; Sagar, R (Royal Astronomical Society, 2001-12)
    The extinction law and the variation of colour excess with position, luminosity and spectral class in young open star clusters NGC 663, NGC 869, NGC 884, NGC 1502, NGC 1893, NGC 2244, NGC 2264, NGC 6611, Tr 14, Tr 15, Tr ...
  • A photometric-dynamic model to simulate coma and jets from a comet. Application to comet Hale-Bopp (C/1995 O1) 
    Vasundhara, R (EDP Sciences, 2002-01)
    A model to compute the trajectories of dust grains ejected by comets to simulate intensity and polarization maps on the sky plane is presented. The model is used to constrain the silicate to organic mass ratio, porosity ...
  • Characterization of MOEMS-based adaptive mirror for wavefront correction 
    Chinnappan, V; Saxena, A. K; Sreenivasan, A (Astronomical Society of India, 2002-09)
    In real-time wavefront compensation techniques, a conjugate surface of the incoming aberrated wavefront is to be created in real-time. Two types of mirrors are used for this purpose. The first one is a tip-tilt mirror ...
  • Performance of the low light level CCD camera for speckle imagmg 
    Saha, S. K; Chinnappan, V (Astronomical Society of India, 2002-09)
    A new generation CCD detector caJ.led low light level OOD (L3CCD) that performs like an intensified CCD without incorporating a micro channel plate (MOP) for light amplification was procured and tested. A series of ...

Search DSpace

Browse

My Account