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Browsing by Author "Sagar, R"

Browsing by Author "Sagar, R"

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  • Possible Microlensing Event in the direction of M31 
    Joshi, Y. C; Pandey, A. K; Narasimha, D; Sagar, R (Astronomical Society of India, 2003)
    The Cousin R and I band photometric observations of ~ 13 x 13 field in the direction of M31 galaxy have been carried out during 1999-2001 to search for microlensing events using pixel technique. Here we report a microlensing-like ...
  • A possible scenario for the formation of the composite Large Magellanic Cloud star cluster NGC 2214 
    Bhatt, H. C; Sagar, R (Astronomical Society of India, 1992)
    The total masses and relaxation times for the two stellar populations (old and young) in the star cluster NGC 2214 are estimated. The total masses are found to be comparable. While the older population may be dynamically ...
  • 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 ...
  • Profile fitting for the stellar photometry 
    Sagar, R (Tata Institute of Fundamental Research, 1988)
    The point spread functions used for doing photometry on two-dimensional stellar images are described. Analytical functions used for this purpose are discussed and it is indicated that amongst them modified Lorentzian fits ...
  • Prolonged intranight optical quiescence of the classical BL Lac object PKS 0735+178 
    Goyal, A; Gopal-Krishna; Anupama, G. C; Sahu, D. K; Sagar, R; Britzen, S; Karazous, M; Aller, M. F; Aller, H. D (Astronomical Society of the Pacific, 2009-09)
    We report our extensive intranight optical monitoring of the well known low-energy peaked (LBL) BL Lac object PKS 0735+178. This long-term follow-up consists of R-band monitoring for a minimum duration of ˜ 4 hours, on 17 ...
  • Proposed microthermal measurements at Devasthal 
    Pant, P; Sagar, R (Astronomical Society of India, 1998)
  • The Puppis OB III association: polarization measurements 
    Bhatt, H. C; Jain, S. K; Sagar, R (European Southern Observatory, 1998-03)
    Optical linear polarization measurements of association members and field stars in the region of the Puppis OB III association are presented. The association members are found to have larger values of polarization than the ...
  • 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 ...

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