Research Publications Based on data from Indian Astronomical Observatory: Recent submissions

  • Optical variability of radio-intermediate quasars 
    Goyal, Arti; Gopal-Krishna; Joshi, S; Sagar, R; Wiita, Paul J; Anupama, G. C; Sahu, D. K (Blackwell Publishing, 2010-02)
    We report the results of our intensive intranight optical monitoring of eight optically bright `radio-intermediate quasars' (RIQs) having flat or inverted radio spectra. The monitoring was carried out in R band on 25 nights ...
  • Unusual optical quiescence of the classical BL Lac object PKS 0735+178 on intranight time scale 
    Goyal, A; Gopal-Krishna; Anupama, G. C; Sahu, D. K; Sagar, R; Britzen, S; Karouzos, M; Aller, M. F; Aller, H. D (Wiley Blackwell, 2009-07)
    We present the result of our extensive intranight optical monitoring of the well known low-energy peaked BL Lac (LBL) object PKS 0735+178. This long-term follow-up consists of $R$-band monitoring for a minimum duration of ...
  • Exploring pre-main sequence variables of ONC: the new variables 
    Parihar, P. S; Messina, S; Distefano, E; Shantikumar, N. S; Medhi, B. J (Wiley Blackwell, 2009-07)
    Since 2004, we have been engaged in a long-term observing program to monitor young stellar objects in the Orion Nebula Cluster. We have collected about two thousands frames in V, R, and I broad-band filters on more than ...
  • 220 GHz tipping radiometer for monitoring sky opacity at Hanle 
    Ananthasubramanian, P. G; Yamamoto, S; Prabhu, T. P (Astronomical Society of the Pacific, 2002)
    A 220 GHz tipping radiometer is in operation at the Indian Astronomical Observatory, Mt Saraswati, Digpa-ratsa Ri, Hanle (Latitude 32degrees 46' 46".3 N, Longitude 78degrees 57' 51".1 E, Altitude 4500 in above msl) for ...
  • 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 ...
  • 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 ...
  • Nova V4444 Sagittarii 1999 in the early decline and quiescent phases 
    Kamath, U. S; Ashok, N. M; Anupama, G. C (Astronomical Society of India, 2008-12)
    We present near-infrared and optical spectra of the fast nova V4444 Sagittarii at two single epochs in the early decline phase and unfiltered images obtained in quiescence. Based on this and other available data, we discuss ...
  • Night sky at the Indian Astronomical Observatory during 2000-2008 
    Stalin, C. S; Hegde, M; Sahu, D. K; Parihar, P. S; Anupama, G. C; Bhatt, B. C; Prabhu, T. P (Astronomical Society of India, 2008-09)
    This paper presents an analysis of the optical night sky brightness and extinction coefficient measurements in UBVRI at the Indian Astronomical Observatory (IAO), Hanle, during the period 2000–2008. They are obtained from ...
  • Low-resolution spectroscopy of high galactic latitude objects: a search for CH stars 
    Goswami, A; Bama, P; Shantikumar, N. S; Devassy, D (Astronomical Society of India, 2007-09)
    Properties of CH stars like iron deficiency and enrichment of carbon and heavy elements can provide valuable inputs to our understanding of nucleosynthesis. In particular, these parameters provide strong observational ...
  • Pre-main sequence stars, emission stars and recent star formation in the Cygnus region 
    Bhavya, B; Mathew, B; Subramaniam, A (Astronomical Society of India, 2007-09)
    The recent star formation history in the Cygnus region is studied using 5 clusters (IC 4996, NGC 6910, Berkeley 87, Biurakan 2 and Berkeley 86). The optical data from the literature are combined with the 2MASS data to ...
  • Further evidence for intra-night optical variability of radio-quiet quasars 
    Goyal, Arti; Gopal-Krishna; Sagar, R; Anupama, G. C; Sahu, D. K (Astronomical Society of India, 2007-06)
    Although well established for BL Lac objects and radio-loud quasars, the occurrence of intra-night optical variability (INOV) in radio-quiet quasars is still debated, primarily since only a handful of INOV events with good ...
  • Triggered star formation and evolution of T-Tauri stars in and around bright-rimmed clouds 
    Chauhan, N; Pandey, A. K; Ogura, K; Ojha, D. K; Bhatt, B. C; Ghosh, S. K; Rawat, P. S (Blackwell Publishing, 2009-06)
    The aim of this paper is to quantitatively testify the `small-scale sequential star formation' hypothesis in and around bright-rimmed clouds (BRCs). As a continuation of the recent attempt by Ogura et al., we have carried ...
  • Star formation in blue compact dwarf galaxies: Mkn 104 and I Zw 97 
    Ramya, S; Sahu, D. K; Prabhu, T. P (Blackwell Publishing, 2009-06)
    Two blue compact dwarf galaxies, Mkn 104 and I Zw 97, are studied photometrically and spectroscopically. Mkn 104 is found to contain three distinct bright star-forming regions, whereas I Zw 97 is found to contain three ...
  • High altitude gamma ray observatory at Hanle 
    Sripathi Acharya, B; Cowsik, R; Bhat, P. N; Chitnis, V. R; Vishwanath, P. R; Prabhu, T. P; Srinivasan, R (International Union of Pure and Applied Physics, 2003-07)
    We have carried out Monte Carlo simulations to study the nature of Cherenkov light pool generated by γ -ray and proton primaries for the altitude of Hanle(4515m amsl) in the Himalayas, the site of proposed HAGAR experiment. ...
  • Spectroscopic survey of ASAS eclipsing variables: search for chromospherically active eclipsing binary stars - I 
    Parihar, P. S; Messina, S; Bama, P; Medhi, B. J; Muneer, S; Velu, C; Ahmad, A (Royal Astronomical Society, 2009-05)
    We have started a spectroscopic survey to identify new chromospherically active components and low-mass pre-main sequence (PMS) stars in recently discovered All Sky Automated Survey (ASAS) eclipsing binaries. In this paper, ...
  • The broad-line type ic supernova SN 2007ru: adding to the diversity of type ic supernovae 
    Sahu, D. K; Tanaka, M; Anupama, G. C; Gurugubelli, U. K; Nomoto, K (Institute of Physics, 2009-05)
    Photometric and spectral evolution of the Type Ic supernova SN 2007ru until around 210 days after maximum are presented. The spectra show broad spectral features due to very high expansion velocity, normally seen in ...
  • Type Ib supernova 2008d associated with the luminous x-ray transient 080109: an energetic explosion of a massive helium star 
    Tanaka, M; Tominaga, N; Nomoto, K; Valenti, S; Sahu, D. K; Minezaki, T; Yoshii, Y; Yoshida, M; Anupama, G. C; Benetti, S; Chincarini, G; Valle, M. D; Mazzali, P. A; Pian, E (The American Astronomical Society, 2009-02)
    We present a theoretical model for supernova SN 2008D associated with the luminous X-ray transient 080109. The bolometric light curve and optical spectra of the SN are modeled based on the progenitor models and the explosion ...
  • Optical photometry and spectroscopy of the Type Ibn supernova SN 2006jc until the onset of dust formation 
    Anupama, G. C; Sahu, D. K; Gurugubelli, U. K; Prabhu, T. P; Tominaga, N; Tanaka, M; Nomoto, K (Royal Astronomical Society, 2009-01)
    We present optical UBVRI photometric and spectroscopic data of the Type Ibn supernova SN 2006jc, until the onset of the dust-forming phase. The optical spectrum shows a blue continuum and is dominated by the presence of ...
  • The Peculiar Type Ia Supernova 2005hk 
    Stanishev, V; Taubenberger, S; Blanc, G; Anupama, G. C; Benetti, S; Cappellaro, E; Elias-Rosa, N; Féron, C; Goobar, A; Krisciunas, K; Pastorello, A; Sahu, D. K; Salvo, M. E; Schmidt, B. P; Sollerman, J; Thöne, C. C; Turatto, M; Hillebrandt, W (American Institute of Physics, 2007-08)
    We present a preliminary analysis of an extensive set of optical observations of the Type Ia SN 2005hk. We show that the evolution of SN 2005hk closely follows that of the peculiar SN 2002cx. SN 2005hk is more luminous ...
  • Multiwavelength Analysis of the Intriguing GRB 061126: The Reverse Shock Scenario and Magnetization 
    Gomboc, A; Kobayashi, S; Guidorzi, C; Melandri, A; Mangano, V; Sbarufatti, B; Mundell, C. G; Schady, P; Smith, R. J; Updike, A. C; Kann, D. A; Misra, K; Rol, E; Pozanenko, A; Castro-Tirado, A. J; Anupama, G. C; Bersier, D; Bode, M. F; Carter, D; Curran, P; Fruchter, A; Graham, J; Hartmann, D. H; Ibrahimov, M; Levan, A; Monfardini, A; Mottram, C. J; O'Brien, P. T; Prema, P; Sahu, D. K; Steele, I. A; Tanvir, N. R; Wiersema, K (The American Astronomical Society, 2008-11)
    We present a detailed study of the prompt and afterglow emission from Swift GRB 061126 using BAT, XRT, UVOT data and multicolor optical imaging from 10 ground-based telescopes. GRB 061126 was a long burst (T90=191 s) with ...

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