Research Papers: Recent submissions

  • Mass functions of five distant northern open star clusters 
    Sagar, R.; Griffiths, W. K. (1998)
    We analyse BVI CCD data of five northern open star clusters in the Galaxy in order to determine their mass functions. The clusters are Berkeley 81, Berkeley 99, NGC 6603, NGC 7044 and NGC 7510. They are distant ( ≥3 ...
  • CN and C₂ molecules in the coma of comet C/1995 O1 Hale-Bopp 
    Sanwal, B. B.; Singh, M. (1999)
    The spectrometric observations of the Cornet C/1995 O1 Hale-Bopp were taken through 104 cm telescope of the U.P. State Observatory, Naini Tal using EG & G Spectrograph coupled with an Optical Multi Channel Analyser and ...
  • BVRI CCD photometric standards in the field of GRB 990123 
    Nilakshi; Yadav, R. K. S.; Mohan, V.; Pandey, A. K.; Sagar, R. (1999)
    The CCD magnitudes in Johnson BV and Cousins RI photometric passbands are determined for 18 stars in the field of GRB 990123. These measurements can be used in carrying out precise CCD photometry of the optical transient ...
  • Direct solar ultraviolet irradiance over Nainital, India, in the central Himalayas for clear-sky day conditions during December 2004 
    Srivastava, M. K.; Singh, S.; Saha, A.; Dumka, U. C.; Hegde, P.; Singh, R.; Pant, P. (2006)
    From a high-altitude station, Nainital, India (29.4°N, 79.5°E, 1958 masl), located in the central part of lower Himalayas, the observations made during December 2004 using a pair of Sun photometers (Microtops II) at ...
  • GRB 030227: The first multiwavelength afterglow of an INTEGRAL GRB 
    Castro-Tirado, A. J., ... et al. (including Sagar, R. & Pandey, S. B. and Mohan, V. (2003)
    We present multiwavelength observations of a gamma-ray burst detected by INTEGRAL (GRB 030227) between 5.3 hours and ~1.7 days after the event. Here we report the discovery of a dim optical afterglow (OA) that would not ...
  • Atmospheric extinction at Devasthal, Naini Tal 
    Mohan, V.; Uddin, W.; Sagar, R.; Gupta, S. K. (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 ...
  • Aerosol characteristics at a high-altitude location in central Himalayas: Optical properties and radiative forcing 
    Pant, P.; Hegde, P.; Dumka, U. C.; Sagar, R.; Satheesh, S. K.; Moorthy, K. K.; Saha, A.; Srivastava, M. K. (2006)
    Collocated measurements of the mass concentrations of aerosol black carbon (BC) and composite aerosols near the surface were carried out along with spectral aerosol optical depths (AODs) from a high-altitude station, ...
  • Exploring pre-main-sequence variables of the ONC: The new variables 
    Parihar, P.; Messina, S.; Distefano, E.; Shantikumar, N. S.; Medhi, B. J. (2009)
    Since 2004, we have been engaged in a long-term observing programme to monitor young stellar objects (YSOs) in the Orion Nebula Cluster (ONC). We have collected about 2000 frames in V, R and I broad-band filters on more ...
  • WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007–2008 : Unveiling different emission components 
    Raiteri, C. M., ... et al. (including Gupta, A. C. and Sagar, R.) (2009)
    BL Lacertae is the prototype of the blazar subclass named after it. Yet, it has occasionally shown a peculiar behaviour that has questioned a simple interpretation of its broad-band emission in terms of synchrotron plus ...
  • Observation of semiannual and annual oscillation in equatorial middle atmospheric long term temperature pattern 
    Guharay, A.; Nath, D.; Pant, P.; Pande, B.; Russell III, J. M.; Pandey, K. (2009)
    Extensive measurement of middle atmospheric temperature with the help of lidar data of more than 10 years (1998–2008) and TIMED/SABER data of 7 years (2002– 2008), has been carried out from a low latitude station, Gadanki, ...
  • UBVRI CCD photometric study of the open clusters Basel 4 and NGC 7067 
    Yadav, R. K. S.; Sagar, R. (2003)
    In this paper we present UBV RI CCD photometry in the region of two young open star clusters Basel 4 and NGC 7067 for the first time. Our sample consists of ~4000 stars down to V ~ 21 mag. Stellar surface density profile ...
  • Discovery of pulsations in the Am star HD 13079 
    Martinez, P.; Kurtz, D. W.; Ashoka, B. N.; Chaubey, U. S.; Gupta, S. K.; Leone, F.; Catanzaro, G.; Sagar, R.; Raj, E.; Seetha, S.; Kasturirangan, K. (1999)
    Pulsation in cool main-sequence Am stars is a rare phenomenon observed in a few marginal Am stars and only one classical Am star. The chemically peculiar star HD 13079 is shown to be pulsating with a 78-min period and a ...
  • Surge activities on November 26-28, 1990 
    Uddin, W.; Verma, V. K. (2000)
    We report here a study of 8 solar surges observed in Hα emission on the west solar limb (active region NOAA 6368) on 26, 27 and 28 November 1990. Three surges were observed on 26 November of durations 35, 86 and 40 min at ...
  • Site characterization for the UPSO-TIFR telescope 
    Sagar, R.,...et al. (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 ...
  • Optical observations of the bright long duration peculiar GRB 021004 afterglow 
    Pandey, S. B., ... et al. (2003)
    The CCD magnitudes in Hohnson B, V and Cousins R and I photometric passbands are determined for the bright long duration GRB 021004 afterglow from 2002 October 4 to 16 starting ~ 3 hours after the γ-ray burst. Light curves ...
  • CCD photometry of the Wolf Rayet galaxy Mink 
    Singh, M.; Sanwal, B. B.; Stalin, C. S. (2000)
    We present here the results from B and V photometric observations of the Wolf Rayet galaxy Mink which was observed through the 104 cm telescope of U. P. State Observatory using 1K × 1K CCD. The surface brightness profiles ...
  • Optical and near-infrared observations of the GRB020405 afterglow 
    Masetti, N,. ...et al. (including Pandey, S. B. & Sagar, R.) (2003)
    We report on photometric, spectroscopic and polarimetric monitoring of the optical and near-infrared (NIR) afterglow of GRB020405. Ground-based optical observations, performed with 8 different telescopes, started about 1 ...
  • UBVRI CCD photometry of the OB associations Bochum 1 and Bochum 6 
    Yadav, R. K. S.; Sagar, R. (2003)
    We report the first deep UBVRI CCD photometry of 2460 stars in the field of two poorly studied OB associations Bochum 1 and Bochum 6. We selected 15 and 14 probable members in Bochum 1 and Bochum 6 respectively using ...
  • Rapid optical variability in radio-quiet QSOs 
    Gopal-Krishna; Gupta, A. C.; Sagar, R.; Wiita, P. J.; Chaubey, U. S.; Stalin, C. S. (2000)
    We report results of the observations at the Vainu Bappu Observatory and the Uttar Pradesh State Observatory of eight radio-quiet quasi-stellar objects (RQQSOs) during 1996-99. This is a part of our ongoing programme to ...
  • A comparative study of intra-night optical micro-variability of high luminosity AGN classes 
    Stalin, C. S. (2003)
    This thesis explores mainly the problem of the radio loudness dichotomy in quasars. This is addressed by carrying out an extensive search for intra-night optical variability (INOV) in seven sets of optically luminous ...

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