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Browsing by Author "Stalin, C. S"

Browsing by Author "Stalin, C. S"

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  • 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 ...
  • Determination of the size of the dust torus in H0507+164 through optical and infrared monitoring 
    Amit Kumar; Rakshit, S; Kshama, S. K; Stalin, C. S; Mathew, B; Hoenig, Sebastian; Gandhi, Poshak; Sagar, R; Pandge, M. B (Oxford University Press on behalf of the Royal Astronomical Society, 2018-04)
    The time delay between flux variations in different wavelength bands can be used to probe the inner regions of active galactic nuclei (AGNs). Here, we present the first measurements of the time delay between optical and ...
  • Discovery of soft and hard X-ray time lags in low-mass AGNs 
    Mallick, L; Wilkins, D. R; Alston, W. N; Markowitz, A; Marco, B. De; Parker, M. L; Lohfink, A. M; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-05)
    The scaling relations between the black hole (BH) mass and soft lag properties for both active galactic nuclei (AGNs) and BH X-ray binaries (BHXRBs) suggest the same underlying physical mechanism at work in accreting BH ...
  • Dissecting star formation in the "Atoms-for-Peace" galaxy UVIT observations of the post-merger galaxy NGC7252 
    George, K; Joseph, P; Cote, P; Ghosh, S. K; Hutchings, J. B; Mohan, Rekhesh; Postma, J; Sankarasubramanian, K; Sreekumar, P; Stalin, C. S; Subramaniam, A; Tandon, S. N (EDP Sciences, 2018-06)
    Context. The tidal tails of post-merger galaxies exhibit ongoing star formation far from their disks. The study of such systems can be useful for our understanding of gas condensation in diverse environments. Aims. The ...

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