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Browsing by Author "Stalin, C. S"

Browsing by Author "Stalin, C. S"

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  • Broad-band study of OQ 334 during its flaring state 
    Prince, Raj; Khatoon, Rukaiya; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-04)
    The blazar OQ 334 displayed a γ-ray flare in 2018, after being in the long quiescent γ-ray state since 2008. Subsequent to the flare, the source was in a higher γ-ray flux state and again flared in 2020. We present here ...
  • Broadband observations of high redshift blazars 
    Paliya, Vaidehi S; Parker, M. L; Fabian, A. C; Stalin, C. S (IOP Publishing, 2016-07-01)
    We present a multi-wavelength study of four high redshift blazars, S5 0014+81 (z = 3.37), CGRaBS J0225+1846 (z = 2.69), BZQ J1430+4205 (z = 4.72), and 3FGL J1656.2−3303 (z = 2.40) using quasi-simultaneous data from the ...
  • Broadband observations of the gamma-ray emitting narrow line Seyfert 1 galaxy SBS 0846+513 
    Paliya, Vaidehi S; Rajput, Bhoomika; Stalin, C. S; Pandey, S. B (IOP Publishing, 2016-03)
    We present the results of our broadband study of the γ -ray emitting narrow line Seyfert 1 ( NLSy1 ) galaxy SBS 0846 + 513 ( z = 0.585 ) . This includes multiband fl ux variations, γ -ray spectral analysis, ...
  • A Catalog of Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey Data Release 12 
    Rakshit, S; Stalin, C. S; Chand, H; Zhang, Xue-Guang (IOP Publishing, 2017-04)
    We present a new catalog of narrow-line Seyfert 1 (NLSy1) galaxies from the Sloan Digital Sky Survey Data Release 12 (SDSS DR12). This was obtained by a systematic analysis through modeling of the continuum and emission ...
  • CCD photometry of the Wolf Rayet galaxy Mink 
    Singh, M; Sanwal, B. B; Stalin, C. S (Astronomical Society of India, 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 x 1K CCD. The surface brightness profiles ...
  • Changing look AGN Mrk 590: broad-line region and black hole mass from photometric reverberation mapping 
    Amit Kumar Mandal; Schramm, Malte; Rakshit, Suvendu; Stalin, C. S; Vijarnwannaluk, Bovornpratch; Rujopakarn, Wiphu; Poshyachinda, Saran; Kouprianov, Vladimir V; Haislip, Joshua B; Reichar, Daniel E; Sagar, R; Mathew, Blesson (Oxford University Press on behalf of Royal Astronomical Society, 2021-12)
    We present the results of photometric reverberation mapping observations on the changing look active galactic nucleus Mrk 590 at z = 0.026. The observations were carried out from 2018 July to December using broad-band B-, ...
  • A Comparative Study of Intra-night Optical Micro-variability of High Luminosity AGN Classes 
    Stalin, C. S (Astronomical Society of India, 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 ...
  • 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 ...
  • Coronal Proerties of the Seyfert 1 Galaxy 3C 120 with NuSTAR 
    Priyanka Rani; Stalin, C. S (IOP Publishing, 2018-04-01)
    We present a measurement of the cut-off energy, a proxy for the temperature of the corona in the nuclear continuum of the Seyfert 1 galaxy 3C 120 using ~120 ks of observation from NuSTAR. The quality broadband spectrum ...
  • Correlation between optical and γ -ray flux variations in bright flat spectrum radio quasars 
    Rajput, Bhoomika; Stalin, C. S; Sahayanathan, S (Oxford University Press on behalf of the Royal Astronomical Society, 2020-11)
    Blazars are known to show flux variations over a range of energies from low-energy radio to high-energy γ-rays. Cross-correlation analysis of the optical and γ-ray light curves in blazars shows that flux variations are ...
  • Correlation between optical and γ-ray flux variations in BL Lacs 
    Rajput, Bhoomika; Shah, Zahir; Stalin, C. S; Sahayanathan, S; Rakshit, S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-06)
    We report here results of the analysis of correlated flux variations between the optical and GeV γ-ray bands in three bright BL Lac objects, namely AO 0235+164, OJ 287, and PKS 2155−304. This was based on the analysis of ...
  • Correlation between optical flux and polarization variations in flat-spectrum radio quasars on diverse time-scales 
    Pandey, Ashwani; Bhoomika, R; Stalin, C. S (Oxford University Press on behalf of Royal Astronomical Society, 2022-02)
    Study of the polarization behaviour in blazars is a powerful tool to discern the role of the magnetic field in the variable emission process in their relativistic jets. We present here the results of our systematic ...
  • COSMOGRAIL: Measuring Time Delays of Gravitationally Lensed Quasars to Constrain Cosmology 
    Tewes, M; Courbin, F; Meylan, G; Kochanek, C. S; Eulaers, E; Cantale, N; Mosquera, A. M; Asfandiyarov, I; Magain, P; Van Winckel, H; Sluse, D; Keerthi, R. K. S; Stalin, C. S; Prabhu, T. P; Saha, P; Dye, S (ESO, 2012-12)
    COSMOGRAIL is a long-term programme for the photometric monitoring of gravitationally lensed quasars. It makes use of several medium-size telescopes to derive long and well-sampled light curves of lensed quasars, in order ...
  • COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses*,**, XII. Time delays of the doubly lensed quasars SDSS J1206+4332 and HS 2209+1914 
    Eulaers, E; Tewes, M; Magain, P; Courbin, F; Asfandiyarov, I; Ehgamberdiev, S; Rathna Kumar, S; Stalin, C. S; Prabhu, T. P; Meylan, G; Van Winckel, H (EDP Sciences, 2013-05)
    Aims. Within the framework of the COSMOGRAIL collaboration we present 7- and 8.5-year-long light curves and time-delay estimates for two gravitationally lensed quasars: SDSS J1206+4332 and HS 2209+1914. Methods. We ...
  • COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. XIV. Time delay of the doubly lensed quasar SDSS J1001+5027 
    Rathna Kumar, S; Tewes, M; Stalin, C. S; Courbin, F; Asfandiyarov, I; Meylan, G; Eulaers, E; Prabhu, T. P; Magain, P; Van Winckel, H; Ehgamberdiev, Sh (EDP Sciences, 2013-09)
    This paper presents optical R-band light curves and the time delay of the doubly imaged gravitationally lensed quasar SDSS J1001+5027 at a redshift of 1.838. We have observed this target for more than six years, between ...
  • Curvit: An open-source Python package to generate light curves from UVIT data 
    Joseph, P; Stalin, C. S; Tandon, S. N; Ghosh, S. K (Indian Academy of Sciences, 2021-10)
    Curvit is an open-source Python package that facilitates the creation of light curves from the data collected by the Ultra-Violet Imaging Telescope (UVIT) onboard AstroSat, India’s first multi-wavelength astronomical ...
  • Detection of IMBHs from microlensing in globular clusters 
    Safonova, M; Stalin, C. S (Elsevier, 2010-07)
    Globular clusters have been alternatively predicted to host intermediate-mass black holes (IMBHs) or nearly impossible to form and retain them in their centres. Over the last decade enough theoretical and observational ...
  • Detection of IMBHs from microlensing in globular clusters 
    Safonova, M; Rahvar, S; Bond, I; Hearnshaw, J; Stalin, C. S (American Institute of Physics, 2008-10)
    Globular clusters have been long predicted to host intermediate-mass black holes (IMBHs) in their centres. The growing evidence that some/all Galactic globular clusters (GCs) could harbour middle range (10/sup2-10/sup4 ...
  • Detection of minute-timescale γ-ray variability in BL Lacertae by Fermi-LAT 
    Pandey, Ashwani; Stalin, C. S (EDP Sciences, 2022-12)
    BL Lacertae, the prototype of the BL Lacertae (BL Lac) category of blazars, underwent a giant γ-ray flare in April 2021. The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (hereafter Fermi-LAT) ...
  • Determination of the mean HI absorption of the intergalactic medium 
    Aghaee, A; Petitjean, P; Srianand, R; Stalin, C. S; Guimaraes, R (Indian Academy of Sciences, 2010-06)
    In recent years, the Lyman-α forest in quasar spectra has been used, together with N-body simulations, to determine the underlying matter distribution in the intergalactic medium (IGM). One of the key parameters to be ...

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