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Browsing by Author "Ghosh, K. K"

Browsing by Author "Ghosh, K. K"

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  • Nova Herculis 1991 
    Iijima, T; Gehrz, R. D; Jones, T. J; Lawrence, G; Sivaraman, K. R; Prabhu, T. P; Ghosh, K. K; Anupama, G. C; Selvakumar, G (Smithsonian Astrophysical Observatory, 1991-04)
  • Observation of an H-alpha outburst in the Be star HR 4123 
    Ghosh, K. K; Apparao, K. M. V; Tarafdar, S. P (American Astronomical Society, 1989-09)
    During routine monitoring of the Be star HR 4123 during the year 1987-1988, a burst of H-alpha emission was observed on May 11, 1987. The increase was observed on May 9 and lasted until June 7, peaking to an equivalent ...
  • Observations of BN and AN stars: New Be stars 
    Ghosh, K. K; Apparao, K. M. V; Pukalenthi, S (The European Southern Observatory, 1999-01)
    From a survey of spectra of Bn/An stars, we have detected seven new Be stars: HR 1056 (A0Vn), 1544 (A1Vn), 2191 (A0Vnn), 2300 (B8Vn), 3134 (B9.5 Vn), 3878 (B0.5 IIIn) and 4552 (B9IIIpSi). H_alpha profiles of these stars ...
  • Optical Microvariability of Blazars 
    Ghosh, K. K; Kim, C; Ramsey, B. D; Soundararajaperumal, S (Korean Astronomical Society, 2001-04)
    We present the results of optical differential photometry of five blazars [PKS 0219+428(3C66A), PKS 0235+164(AO 0235+16), H0414+019, PKS 0851+202(OJ 287), and QSO 1807+698(3C371)] that were observed on 7 nights between ...
  • Optical Variability of BL Lacertae during the Major Outburst of 1997 
    Ghosh, K. K; Ramsey, B. D; Sadun, A. C; Soundararajaperumal, S; Wang, J (The American Astronomical Society, 2000-07)
    We have undertaken an investigation of recent flux variability in BL Lac. We present optical observations taken over 22 nights documenting major as well as minor outbursts. This has been combined, for purposes of multifrequency ...
  • Optical Variability of Blazars 
    Ghosh, K. K; Ramsey, B. D; Sadun, A. C; Soundararajaperumal, S (The American Astronomical Society, 2000-03)
    In this paper we show the results of our monitoring the flux variability of 15 blazars, within the redshift range of 0.07-2.06, all with a visual magnitude range between 14 and 20 mag. Because blazars have displayed ...
  • Origin of MeV gamma-ray emissions from blazars 
    Ghosh, K. K; Ramsey, B. D; Sivaram, C (Elsevier Science B. V, 1999-06)
    We have developed a model for MeV emission from blazars that involves the production of MeV gamma-rays through Inverse Compton (IC) scattering of electrons in the blob of a jet, with the UV photons of the accretion disk. ...
  • Physics of the phase changes of Be stars 
    Ghosh, K. K (International Astronomical Union, 1994)
    Based on Spectrosopic observations of more than 100 Be stars, we present the reuslts of the phase changes of Be stars.
  • Probability for the formation of complex ring molecules in interstellar medium and their detection proposal 
    Ghosh, K. K (International Astronomical Union, 1987)
    The pathways for the formation and destruction processes of ring molecules in the interstellar medium are proposed and their abundances are calculated under steady state conditions. The calculated abundances are of the ...
  • Quenching of NO2 continuum by NO, H2O & CH4 
    Ghosh, K. K (Publications & Information Directorate, CSIR, 1984-10)
    The K/A ratio, where K is the quenching rate coefficient of NO2 continuum by NO2, H2O and CH4 and A is the transition probability of NO2 continuum, has been measured using flowing afterglow method. The obtained values are ...
  • Rapid continuum level variability in Be stars earlier than B2 
    Ghosh, K. K (American Astronomical Society, 1990-05)
    H-alpha profiles for 12 Be stars and four standard stars were obtained on six nights in January and February, 1988, in order to search for rapid spectral variability in these stars. The results show that the Be stars earlier ...
  • Rapid H-alpha variability in Phi Persei 
    Ghosh, K. K; Sanjeevkumar, T; Jaykumar, K; Kuppuswamy, K; Rosario, M. J (Astronomical Society of the Pacific, 1988-06)
    A search for rapid variability of H-alpha with a time resolution from 30 to 45 seconds is performed for Phi Per. In total, 42 spectra in H-alpha were obtained during three nights. Results show the presence of rapid irregular ...
  • Rapid simultaneous observations of Fe II and Balmer emission lines of X OPH 
    Ghosh, K. K; Jayakumar, K (D. Reidel Publishing Co., 1988-02)
    Sudden brightening of Fe II and Balmer (Hβ and Hα) lines of X Oph was observed on 28 - 29 May, 1986. Equivalent width of Fe II and Hβ lines increased by a factor of two and that for Hα line by a factor of four, during the ...
  • Rapid variations of H-alpha emission strength of eight Be stars 
    Ghosh, K. K (Kluwer Academic Publishers, 1988-08)
    Rapid observations of H profiles of eight Be stars have been obtained and it is found that rapid (in a time-scale of 4 to 6 minutes) and irregular variations of total emission strength of H line are present in these stars. ...
  • Recent mass loss episode of the Be Star omicron And 
    Ghosh, K. K; Jaykumar, K; Rosario, M. J; Appakutty, M (Konkoly Observatory, 1986-05)
  • Recent onset of an outburst in mu centauri 
    Ghosh, K. K; Velu, C; Kuppuswamy, K; Jaykumar, K; Rosario, M. J (Konkoly Observatory, 1987-08)
  • Search for rapid H-alpha variability studies in Be stars - 28 Eri, X Ophiuchi, 66 Ophiuchi and Pi Aquarii 
    Ghosh, K. K (EDP Sciences, 1988-10)
    In order to search for rapid Hα variability in Be stars, a series of Hα profiles were observed on a time scale of few minutes for 28 Eri, X Oph, 66 Oph and π Aqr. In total, 95 and 54 Hα profiles were obtained for the program ...
  • Search for rapid spectral variability in Be stars - Alpha Columbae, Rho Carinae and Eta Centauri 
    Ghosh, K. K; Pukalenthi, S; Jaykumar, K; Kuppuswamy, K; Sanjeevkumar, T; Muniandi, A (European Southern Observatory, 1990-03)
    A series of H-alpha profiles (in total 1006 spectra in the H-alpha region) with the time resolution around 45 s were obtained on six nights between January 29 and February 7, 1988, to search for rapid spectral variability ...
  • Search for rapid spectral variability in Psi(9) Aurigae 
    Ghosh, K. K (Astronomical Society of the Pacific, 1989-09)
    Observations of Psi(9) Aur on five nights between January 29 and February 3, 1988 were conducted as part of a search for rapid spectral variability in Be stars. In addition, a series of H-alpha profiles with a time resolution ...
  • Search for rapid V/R variability in Eta CEN 
    Ghosh, K. K (Royal Astronomical Society, 1989-10)
    In order to search for rapid V/R variability in the Be star, Eta Cen, a series of H-alpha profiles of this star were observed on three nights between May 28 and June 3, 1986. A method of estimating the standard deviation ...

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