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Browsing Publications of Astronomical Society of India by Author "Sagar, R"

Browsing Publications of Astronomical Society of India by Author "Sagar, R"

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  • An Analysis of Proper Motion and Membership Probability in Open Clusters 
    Sagar, R (Astronomical Society of Indian, 1987-12)
    An analysis of the proper motion data and membership probability has been carried out for nine open clusters. The effects of observational errors on the parameters characterzing the frequency distributions of cluster and ...
  • Atmospheric extinction at Devasthal, Naini Tal 
    Mohan, V; Uddin, W; Sagar, R; Gupta, S. K (Astronomical Society of India, 1999)
    The atmospheric extinction coefficients in Johnson U, B, V, R and I photometric passbands are determined for the first time at Devasthal, Naini Tal during 1998 and 1999. A solid state stellar photometer mounted on a 52-cm ...
  • Binary star clusters in galaxies : Our galaxy 
    Subramaniam, A; Gorti, U; Sagar, R; Bhatt, H. C (Astronomical Society of India, 2000)
  • BVRI CCD photometric standards in the field of GRB 990123 
    Nilakshi; Yadav, R. K. S; Mohan, V; Pandey, A. K; Sagar, R (Astronomical Society of India, 1999)
    The CCD magnitudes in Johnson BV and Cousins RI photometric passbands are determined for 18 stars in the field of GRB 990123. These mesurements can be used in carrying out precise CCD photometry of the optical transient ...
  • CCD imaging of gamma ray burster fields 
    Bhargavi, S. G; Cowsik, R; Pati, A. K; Sagar, R (Astronomical Society of India, 1998)
  • CCD photometry of the galactic open star clusters. I - King 10 
    Mohan, V; Pandey, A. K; Paliwal, D. C; Sagar, R; Mahra, H. S (Astronomical Society of India, 1992)
    CCD photometry of the open cluster King 10 has been carried out in the UBVRI photometric passbands down to V of about 19.5 mag. The reddening for the cluster region is found to be variable. A distance of 3.2 kpc has been ...
  • CCD photometry of the galactic star clusters Be 15, Be 71 and King 1 
    Lata, S; Mohan, V; Sagar, R (Astronomical Society of India, 2004-12)
    We present UBV RI CCD photometry of three open star clusters Be 15, Be 71 and King 1 for the fist time. Base on these data, optical colour magnitude diagrams (CMDs) for the stars in the clusters down to V = 22 mag are ...
  • CCD photometry of the unstudied galactic star clusters Be 10, Be 67 and To 5 
    Lata, S; Mohan, V; Pandey, A. K; Sagar, R (Astronomical Society of India, 2004-03)
    We present the broad band Johnson U BV and Cousins RI CCD photometric observations for open clusters Be 10, Be 67 and To 5. So far no photometric study of these clusters is published. The colour-magnitude diagrams indicate ...
  • A comparative study of the intra-night optical variability of powerful AGNs 
    Stalin, C. S; Gopal-Krishna; Sagar, R; Wiita, P. J (Astronomical Society of India, 2002-09)
    In order to address a currently much debated issue, we are carrying out a systematic search for intra-night optical micro-variability in major classes of powerful (M'II ~ -23.0 mag) active galactic nuclei (AGNs). Our ...
  • A deep V I CCD photometric study of the neglected galactic star cluster NGC 6631 
    Sagar, R; Naidu, B. N; Mohan, V (Astronomical Society of India, 2001)
    We present the V I CCD photometric observations of about 5500 stars up to a limiting magnitude of V ~ 20 in an area of ~ 16? x 16? around the cluster NGC 6631. The cluster parameters determined for the first time by fitting ...
  • Discovery of a planetary system around 51 Pegasus 
    Sagar, R (Astronomical Society of India, 1996)
  • Discovery of pulsations in HD 98851 
    Joshi, S; Girish, V; Martinez, P; Sagar, R; Ashoka, B. N; Gupta, S. K; Seetha, S; Chaubey, U. S; Kurtz, D. W (Astronomical Society of India, 2001)
    Using the UPSO 1-m Sampurnanand reflector telescope equipped with a fast photometer, we observed the chemically peculiar (CP) star HD 98851 for a total of around 30 hours on 5 different nights between January to April 2000. ...
  • Distribution of stellar mass in young star clusters of our Galaxy and nearby galaxies 
    Sagar, R (Astronomical Society of India, 2000)
    Stellar mass distribution in young star clusters of our Galaxy, the Magellanic Clouds and the nearby local groups of galaxies has been used to investigate the universality of initial mass function and presence of mass ...
  • Effect of mass segregation on mass function of young open clusters 
    Pandey, A. K; Mahra, H. S; Sagar, R (Astronomical Society of India, 1992)
    The effect of mass segregation on cluster mass function has been studied and it is found that the slope of the mass function is steeper in the outer part of the open clusters. Since derived dynamical relaxation time is ...
  • Emission from GRBs and their afterglows : Indian observations 
    Sagar, R (Astronomical Society of India, 2001)
    The study of Gamma-ray bursts, electromagnetically the most luminous events in the Universe though only for a few seconds, was revolutionized in 1997 when the Italian-Dutch X-ray satellite BeppoSAX started providing the ...
  • Field star contamination in open star cluster NGC 2301 
    Mohan, V; Sagar, R (Astronomical Society of Indian, 1988-12)
    Photographic photometry of about 900 stars down to V = 17 mag has been carried out in the region of the open cluster NGC 2301. The cluster region seems to be severely contaminated by field stars. Statistical criteria yield ...
  • 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 ...
  • The Gap in the H-R Diagram of Open Clusters with Special Reference to NGC 2169, NGC 1778 and Tr I 
    Sagar, R; Joshi, U. C (Astronomical Society of India, 1978-06)
    The colour-magnitude diagrams of the open clusters NGC 1778 and Tr I indicate the presence of gaps on the rising branches of the evolving main sequnces. The positions of these gaps are compared with those found in other ...
  • Globular cluster systems in giant elliptical galaxies : a probe for the galaxy formation and evolution 
    Subramaniam, A; Sagar, R (Astronomical Society of India, 2000)
    Most of the globular clusters in the universe reside in gaint elliptical galaxies. The number of GCs present in them is about a few thousands. Due to their large distances (> 10 Mpc), it is impossible to observe their ...
  • GRB 000301C with peculiar afterglow emission 
    Sagar, R; Mohan, V; Pandey, S. B; Pandey, A. K; Stalin, C. S; Castro-Tirado, A. J (Astronomical Society of India, 2000)
    The CCD magnitudes in Johnson V and Cousins R and I photometric passbands are determined for GRB 000301C afterglow starting ~ 1.5 day after the γ - ray burst. In fact we provide the earliest optical observations for this ...

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