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Browsing by Author "Sagar, R"

Browsing by Author "Sagar, R"

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  • Quasar catalogue for the astrometric calibration of the forthcoming ILMT survey 
    Mandal, A. K; Pradhan, Bikram; Surdej, Jean; Stalin, C. S; Sagar, R; Mathew, B (Indian Academy of Sciences, 2020-12)
    Quasars are ideal targets to use for astrometric calibration of large scale astronomical surveys as they have negligible proper motion and parallax. The forthcoming 4-m International Liquid Mirror Telescope (ILMT) will ...
  • Radial distribution of the integrated light and photometric colours in open star clusters 
    Sagar, R; Bhatt, H. C (Indian Academy of Sciences, 1989-06)
    Mass segregation in the form of preferential concentration of more massive stars in the central regions of a number of open star clusters has been known for some time. In this paper, integrated UBV colors in concentric ...
  • Radio, millimeter and optical monitoring of GRB 030329 afterglow: constraining the double jet model 
    Resmi, L; Ishwara-Chandra, C. H; Castro-Tirado, A. J; Bhattacharya, D; Rao, A. P; Bremer, M; Pandey, S. B; Sahu, D. K; Bhatt, B. C; Sagar, R; Anupama, G. C; Subramaniam, A; Lundgren, A; Gorosabel, J; Guziy, S; de Ugarte Postigo, A; Castro Cerón, J. M; Wiklind, T (EDP Sciences, 2005-09)
    We present radio, millimeter and optical observations of the afterglow of GRB 030329. $UBVR_{\rm C}I_{\rm C}$ photometry is presented for a period of 3 h to 34 days after the burst. Radio monitoring at 1280 MHz has been ...
  • Rapid optical variability of TeV blazars 
    Gopal-Krishna; Goyal, A; Joshi, S; Karthick, C; Sagar, R; Wiita, P. J; Anupama, G. C; Sahu, D. K (Wiley-Blackwell, 2011-09)
    In this first systematic attempt to characterize the intranight optical variability (INOV) of TeV-detected blazars, we have monitored a well-defined set of nine TeV blazars on total 26 nights during 2004–10. In this R- or ...
  • REMAP: Determination of the inner edge of the dust torus in AGN by measuring time delays 
    Mandal, A. K; Rakshit, S; Pal, I; Stalin, C. S; Sagar, R; Mathew, B. (Societe Royale des Sciences de Liege, 2019-10)
    Active galactic nuclei (AGN) are high luminosity sources powered by accretion of matter onto super-massive black holes (SMBHs) located at the centres of galaxies. According to the Unification model of AGN, the SMBH is ...
  • SAO 75669: A late type giant behind the molecular cloud MBM 12 
    Bhatt, H. C; Sagar, R; Subramaniam, A; Gorti, U; Chandrasekhar, T; Ashok, N. M; Ragland, S (European Southern Observatory, 1994-09)
    Photometric and spectroscopic observations of the star SAO 75669 in the region of the high galactic latitude molecular cloud MBM 12 are presented. The optical, near-infrared and far-infrared IRAS photometric magnitudes ...
  • Science at high-altitude sites of ARIES-astrophysics and atmospheric sciences 
    Sagar, R; Naja, M; Maheswar, G; Srivastava, A. K (Indian National Science Academy, 2014-11)
    In this article we discuss various frontline research activities those are being carried out in the fields of Astronomy and Astrophysics and Atmospheric Sciences at Aryabhatta Research Institute of Observational Sciences ...
  • Scientific capabilities and advantages of the 3.6 meter optical telescope at Devasthal, Uttarakhand 
    Omar, A; Kumar, B; Maheswar, G; Sagar, R (Current Science Association, 2015-08)
    India’s largest 3.6 m aperture optical telescope has been successfully installed in the central Himalayan region at Devasthal, Nainital district, Uttarakhand. The primary mirror of the telescope uses the active optics ...
  • Scientific potential of the Indo-Belgian 3.6-m DOT in the field of Galactic Astronomy 
    Sagar, R; Kumar, B; Subramaniam, A (Societe Royale des Sciences de Liege, 2019-10)
    India and Belgium have jointly established two 4-meter class optical telescopes at Devasthal located in Nainital, India. After successful installation of the 3.6-m modern new technology Devasthal Optical Telescope (DOT) ...
  • Scientific Summary of the First BINA Workshop 
    Sagar, R (Bulletin de la Societe Royale des Sciences de Liege, 2018-04)
    "Scientific summary of the first Belgo-Indian Network for Astronomy & Astrophysics (BINA) workshop is presented here. In the workshop, invited talks were supplemented with the contributory talks and poster paper ...
  • A search for intra-night optical variability in radio-quiet QSOs 
    Gopal-Krishna; Sagar, R; Witta, P. J (Royal Astronomical Society, 1993-06-15)
    We report results from a new program, using the 2.34-m Vainu Bappu Telescope, to search for intra-night optical variability in five QSOs which are radio-quiet but optically bright and luminous. Our limited data show mild ...
  • Search for Microlensing Events Towards M31 Galaxy 
    Joshi, Y. C; Pandey, A. K; Narasimha, D; Sagar, R (Astronomical Society of India, 2001)
    M31, the prominent galaxy of the Local Group, is located at a distance of about 700 kpc. Due to its convenient orientation, it is an alluring target for gravitational microlensing to search for massive astrophysical compact ...
  • Seeing and microthermal measurements near Devasthal top 
    Stalin, C. S; Sagar, R; Pant, P; Mohan, V; Kumar, B; Joshi, Y. C; Yadav, R. K. S; Joshi, S; Chandra, R; Durgapal, A. K; Uddin, W (Astronomical Society of India, 2001)
    Results of the seeing measurements carried out near Devasthal top on 43 nights during March to April 1999 are presented. Open air seeing measurements were carried out with a differential image motion monitor (DIMM) using ...
  • Site characterization for the UPSO-TIFR telescope 
    Sagar, R; Uddin, W; Pandey, A. K; Stalin, C. S; Mohan, V; Sanwal, B. B; Gupta, S. K; Yadav, R. K. S; Durgapal, A. K; Joshi, S; Kumar, B; Gupta, A. C; Joshi, Y; Srivastava, J. B; Chaubey, U. S; Singh, M; Pant, P; Gupta, K. G; Padalia, T. D (Astronomical Society of India, 2000)
    The Uttar Pradesh State Observatory, Naini Tal and Tata Institute of Fundamental Research, Mumbai plan to install jointly a 3 metre size optical telescope at Devasthal located east of Naini Tal about 50 km by road. The ...
  • Sky transparency over Naini Tal : A retrospective study 
    Kumar, B; Sagar, R; Rautela, B. S; Srivastava, J. B; Srivastava, R. K (Astronomical Society of India, 2000)
    We present an analysis of the atmospheric extinction coefficients measured during 1964 to 1999 in broad-band photometric passbands at U.P. State Observatory, Naini Tal. The extinction properties are also studied from the ...
  • SN 1993J in M 81: Optical photometry and spectrophotometry during the first two months 
    Prabhu, T. P; Mayya, Y. D; Singh, K. P; Kameswara Rao, N; Ghosh, K. K; Mekkaden, M. V; Pati, A. K; Raveendran, A. V; Reddy, B. E; Sagar, R; Subramaniam, A; Surendiranath, R (The European Southern Observatory, 1995-03)
    CCD photometric and spectrophotometric data on the type IIb supernova 1993J in M 81 (NGC 3031) obtained from Vainu Bappu Observatory, Kavalur, during the first two months since the outburst are reported. The evolution of ...
  • SN 2002ap, the Hypernova of Class Ic 
    Pandey, S. B; Sahu, D. K; Anupama, G. C; Bhattacharya, D; Sagar, R (Astronomical Society of India, 2003)
    The supernova SN 2002ap was discovered in the outer regions of the nearby spiral M74 on January 29.4 UT. Early photometric and spectroscopic observations indicate the supernova belongs to the class of Ic hypernova. Late ...
  • Spatial Distribution of Stellar Mass in the Large Magellanic Cloud Star Clusters 
    Subramaniam, A; Sagar, R; Bhatt, H. C (European Southern Observatory, 1993-06)
    The stellar mass distributions have been studied in halo regions (radius ranging from ~19 to 94 arcsec) of 5 young Large Magellanic Cloud star clusters. Effects of mass segregation have been observed in only NGC 1711. A ...
  • SS 433: results of a recent multiwavelength campaign 
    Chakrabarti, S. K; Anandarao, B. G; Pal, S; Mondal, S; Nandi, A; Bhattacharyya, A; Mandal, S; Sagar, R; Pandey, J. C; Pati, A. K; Saha, S. K (Royal Astronomical Society, 2005-09)
    We conducted a multiwavelength campaign in 2002 September-October, to observe SS 433. We used the Giant Meter Radio Telescope for radio observations, the Physical Research Laboratory Infrared Telescope at Mt Abu for infrared ...
  • Star clusters in the magellanic clouds II. age-dating, classification, and spatio-temporal distribution of the SMC clusters 
    Nayak, P. K; Subramaniam, A; Choudhury, S; Sagar, R (EDP Sciences, 2018-08)
    Aims. We aim to estimate the age and reddening parameters of already identified star clusters within the Small Magellanic Cloud (SMC) in a consistent way using available photometric data, classify them based on their mass ...

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