Research Papers: Recent submissions

  • Cosmic-ray periodicity at 170 days 
    Joshi, A. (1998)
    Power-spectral analysis of cosmic-ray indices (CRI) data for the years 1989–1991 shows a 170-day periodicity of cosmic rays. The periodicity is related to a strong magnetic field. Power- spectral analysis of the ...
  • On the distribution and asymmetry of solar active prominences 
    Verma, V. K. (1999)
    The paper presents the results of a study of the distribution and asymmetry of solar active prominences (SAP) for the period 1957 – 1998 (solar cycles 19 – 23). The east-west (E-W) distribution study shows that the ...
  • Solar log gf values in the infrared J and H bands 
    Stalin, C. S.; Trivedi, C.; Sinha, K.; Sanwal, B. B. (1997)
    Solar IR spectra have been utilized to derive log gf value for atomic lines due to 17 chemical elements. From a recent publication in Astronomy and Astrophysics Supplement, we selected unblended solar lines in the infrared ...
  • Constraining the evolution of ZZ CETI 
    Mukadam, A. S., ... et al. (including Joshi, S.) (2003-09-10)
    We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf ) ZZ Ceti, also called R548. On the basis of observations that span 31 years, we conclude that the ...
  • Coronal holes and flare index: A Correlation Study 
    Joshi, A. (2000)
    The correlation between the presence of coronal holes and flare indices has been inves- tigated for the period from 1976 to 1995. The analysis shows that in the cases of 227 Carrington rotations (CRs) backward time lags ...
  • The afterglow and the host galaxy of GRB 011211 
    Jakobsson, P., ... et al. (including Pandey, S. B.) (2003)
    WWe present optical, near-infrared, and X-ray observations of the optical afterglow (OA) of the X-ray rich, longduration gamma-ray burst GRB 011211. Hubble Space Telescope (HST) data obtained 14, 26, 32, and 59 days after ...
  • The optical afterglow of the not so dark GRB 021211 
    Pandey, S. B.; Anupama, G. C.; Sagar, R.; Bhattacharya, D.; Castro-Tirado, A. J.; Sahu, D. K.; Parihar, P.; Prabhu, T. P. (2003)
    We determine Johnson B,V and Cousins R, I photometric CCD magnitudes for the afterglow of GRB 021211 during the first night after the GRB trigger. The afterglow was very faint and would have been probably missed if no ...
  • Photometric binary content in intermediate/old open clusters 
    Sandhu, T. S.; Pandey, A. K.; Sagar, R. (2003)
    The stellar evolutionary models by Bertelli et al. (1994) have been used to generate synthetic colour–magnitude diagrams (CMDs) of open clusters. A comparison of the synthetic integrated luminosity function (ILF) and ...
  • The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy 
    Castro-Tirado, A. J.,... et. al. (including R. Sagar) (2001)
    Broad-band optical observations of the extraordinarily bright optical afterglow of the intense gamma-ray burst GRB 991208 started ∼2.1 days after the event and continued until 4 Apr. 2000. The flux decay constant of the ...
  • Photometry and low resolution spectroscopy of hot post-AGB candidates 
    Gaubal, G.; Parthasarathy, M.; Kumar, B.; Yadav, R. K. S.; Sagar, R. (2003)
    We have obtained Johnson U, B, V and Cousins R, I photometry and low resolution spectra of a small sample of hot post-AGB candidates. Using the present data in combination with JHK data from 2MASS, infrared data from the ...
  • GRB 000926 and its optical afterglow: Another possible evidence for non-isotropic emission 
    Sagar, R.; Pandey, S. B.; Mohan, V.; Bhattacharya, D.; Castro-Tirado, A. J. (2001)
    The CCD Johnson BV and Cousins RI photometric magnitudes are determined for 20 stars in the field of GRB 000926. They are used to calibrate the present R as well as published BVRI photometric magnitudes of the GRB 000926 ...
  • Identification of 13 Cepheids and 333 other variables in M31 
    Joshi, Y. C.; Pandey, A. K.; Narasimha, D.; Sagar, R.; Eraud, Y. G. (2003)
    We present Cousins R and I band photometry of variable stars in a ∼13` × 13` region in the disk of M31 galaxy, obtained during 141 nights. Of the 26 Cepheid variables present in the region, two are newly discovered, 11 are ...
  • Discovery of unusual pulsations in the cool, evolved Am stars HD 98851 and HD 102480 
    Joshi, S.; Girish, V.; Sagar, R.; Kurtz, D. W.; Martinez, P.; Kumar, B.; Seetha, S.; Ashoka, B. N.; Zhou, A. (2003)
    The chemically peculiar (CP) stars HD 98851 and HD 102480 have been discovered to be unusual pulsators during the ‘Naini Tal–Cape Survey’ programme to search for pulsational variability in CP stars. Time series photometric ...
  • Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the whole earth telescope 
    Handler, G,... et al. (including Joshi, S.) (2003)
    We have acquired new time series photometry of the two pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 with the Whole Earth Telescope. Additional single-site photometry is also presented. We use all these ...
  • A flattening in the optical light curve of SN 2002ap 
    Pandey, S. B.; Anupama, G. C.; Sagar, R.; Bhattacharya, D.; Sahu, D. K.; Pandey, J. C. (2003)
    We present the UBVRc I c broad-band optical photometry of the type Ic supernova SN 2002ap obtained during 2002 February 6–March 23 in the early decline phases and also later on 2002 August 15. Combining these data with the ...
  • Estimation of fried’s parameter from specklegrams of solar features 
    Sridharan, R.; Venkatakrishnan, P.; Verma, V. K. (2002)
    A few methods of estimating Fried’s parameter (r˳) from specklegrams of solar features are described. Some of these methods were used to estimate r˳ for the speckle data obtained from Kodaikanal Observatory (KO), Uttar ...
  • The Naini Tal – Cape survey for pulsations in chemically peculiar A-type stars 
    Martinez, P.; Kurtz, D. W.; Ashoka, B. N.; Chaubey, U. S.; Girish, V.; Gupta, S. K.; Joshi, S.; Kasturirangan, K.; Sagar, R.; Seetha, S. (2001)
    New survey for pulsating, chemically peculiar A- and F-type stars in the northern hemisphere has been initiated using the 1-m telescope at Uttar Pradesh State Observatory in Naini Tal. The survey is primarily structured ...
  • Development of a three channel photometer for UPSO, Naini Tal 
    Ashoka, B. N.; Kumar; Babu, V. C.; Seetha, S.; Girish, V.; Gupta, S. K.; Sagar, R.; Joshi, S.; Narang, P. (2001)
    The design and performance of a portable three channel photometer installed at the Uttar Pradesh State Observatory (UPSO), NainiTal is described. The photometer is modular and the whole unit can be disassembled as individual ...
  • Multicolour CCD photometry of old open clusters: King 5 and Be 20 
    Durgapal, A. K.; Pandey, A. K.; Mohan, V. (2001)
    We present multicolour CCD photometry for two poorly studied open clusters (King 5 and Be 20). Photometry for a field near King 5 was also carried out to estimate the contamination by field stars. The colour magnitude ...
  • Optical and radio observations of the bright GRB 010222 afterglow: evidence for rapid synchrotron cooling 
    Sagar, R.; Stalin, C. S.; Bhattacharya, D.; Pandey, S. B.; Mohan, V.; Castro-Tirado, A. J.; Rao, A. P.; Trushkin, S. A.; Nizhelskij, N. A.; Bermer, M.; Ceron, J. M. C. (2001)
    We report photometric observations of the optical afterglow of GRB 010222 in V, R, and I passbands carried out between 22-77 February 2001 at Nainital. We determine the CCD Johnson BV and Cousins RI photometric magnitude ...

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