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Browsing by Author "Stalin, C. S"

Browsing by Author "Stalin, C. S"

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  • In-orbit performance of UVIT and first results 
    Tandon, S. N; Hutchings, J. B; Ghosh, S. K; Subramaniam, A; George, K|; Girish, V; Kamath, P. U; Kathiravan, S; Kumar, A; Lancelot, J.P; Mahesh, P. K; Mohan, Rekhesh; Murthy, J; Nagabhushana, S; Pati, A. K; Postma, J; Kameswara Rao, N; Sankarasubramanian, K; Sreekumar, P; Sriram, S; Stalin, C. S; Sutaria, F. K; Sreedhar, Yuvraj Harsha; Barve, Indrajit V; Mondal, Chayan; Snehalata Sahu (Indian Academy of Sciences, 2017-06)
    The performance of the ultraviolet telescope (UVIT) on-board AstroSat is reported. The performance in orbit is also compared with estimates made from the calibrations done on the ground. The sensitivity is found to be ...
  • In-orbit performance of UVIT over the past 5 years 
    Ghosh, S. K; Joseph, P; Kumar, A; Postma, J; Stalin, C. S; Subramaniam, A; Tandon, S. N; Barve, Indrajit V; Devaraj, A; George, K; Girish, V; Hutchings, J. B; Kamath, P. U; Kathiravan, S; Lancelot, J. P; Leahy, D; Mahesh, P. K; Mohan, R; Nagabhushana, S; Pati, A. K; Kameswara Rao, N; Sankarasubramanian, K; Sreekumar, P; Sriram, S (Indian Academy of Sciences, 2021-10)
    Over the last 5 years, UVIT has completed observations of more than 500 proposals with ∼800 unique pointings. In addition, regular planned monitoring observations have been made and from their analysis various key parameters ...
  • Intra-night optical variability characteristics of different classes of narrow-line seyfert 1 galaxies 
    Kshama, S. K; Paliya, Vaidehi S; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2017-04)
    In a first systematic effort to characterize the intra-night optical variability (INOV) of different classes of narrow-line Seyfert 1 (NLSy1) Galaxies, we have carried out observations on a sample of radio-loud (RL) and ...
  • Intra-night optical variability monitoring of c-ray emitting blazars 
    Pandian, K Subbu Ulaganatha; Natarajan, A; Stalin, C. S; Pandey, Ashwani; Muneer, S; Natarajan, B (Indian Academy of Sciences, 2022-12)
    We present the results obtained from our campaign to characterize the intra-night optical variability properties of blazars detected by the Fermi large area telescope. This involves R-band monitoring observations of a ...
  • Intra-night Optical Variability Monitoring of Fermi Blazars: First Results from 1.3 m J. C. Bhattacharya Telescope 
    Paliya, Vaidehi S; Stalin, C. S; Ajello, M; Kaur, A (IOP Publishing, 2017-08)
    We report the first results obtained from our campaign to characterize the intra-night-optical variability (INOV) properties of Fermi detected blazars, using the observations from the recently commissioned 1.3 m J. ...
  • Intra-night optical variability of misaligned active galaxies 
    Bhattacharya, Debbijoy; Gulati, S; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2019-03)
    The majority of the γ-ray sources detected by the Fermi Gamma-ray Space Telescope belong to the blazar class of active galactic nuclei (AGNs). In addition to blazars, a minority of non-blazar AGNs is also found to be γ-ray ...
  • Intra-night optical variability of misaligned active galaxies 
    Bhattacharya, Debbijoy; Gulati, S; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2019-03)
    The majority of the γ-ray sources detected by the Fermi Gamma-ray Space Telescope belong to the blazar class of active galactic nuclei (AGNs). In addition to blazars, a minority of non-blazar AGNs is also found to be γ-ray ...
  • Intranight optical variability of γ -ray-loud narrow-line Seyfert 1 galaxies 
    Paliya, Vaidehi S; Stalin, C. S; Kumar, Brijesh; Kumar, Brajesh; Bhatt, V. K; Pandey, S. B; Yadav, K. S (Oxford University Press on behalf of the Royal Astronomical Society, 2013-01-21)
    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope has detected γ-ray emission in about half a dozen narrow-line Seyfert 1 (NLSy1) galaxies. This indicates the presence of relativistic jets in these ...
  • Investigation of the correlation between optical and γ-ray flux variation in the blazar Ton 599 
    Rajput, Bhoomika; Mandal, Amit Kumar; Pandey, Ashwani; Stalin, C. S; Max-Moerbeck, Walter; Mathew, Blesson (Published by Oxford University Press on behalf of Royal Astronomical Society, 2024-02)
    The correlation between optical and γ-ray flux variations in blazars reveals a complex behaviour. In this study, we present our analysis of the connection between changes in optical and γ-ray emissions in the blazar Ton ...
  • Leptonic and hadronic modeling of Fermi-LAT hard spectrum quasars and predictions for high-energy polarization 
    Paliya, Vaidehi S; Zhang, H; Bottcher, M; Ajello, M; Domi­nguez, A; Joshi, M; Hartmann, D; Stalin, C. S (IOP Publishing, 2018-08)
    We present the results of a study of the time-averaged spectral energy distributions (SEDs) of eight flat spectrum radio quasars (FSRQs) present in the second catalog of high energy sources detected beyond 50 GeV by the ...
  • Lepto−Hadronic Origin of γ-ray Outbursts of 3C 279 
    Paliya, Vaidehi S; Diltz, C; Bottcher, M; Stalin, C. S; Buckley, D (Astronomical Society of India, 2015-03)
    The blazar 3C 279 exhibited a giant γ-ray outburst in 2013 December and 2014 April. Apart from the very fast γ-ray flux variability, the spectral nature of the flares were also found to vary significantly between these ...
  • Long term γ-ray variability of blazars 
    Rajput, Bhoomika; Stalin, C. S; Rakshit, S (EDP Sciences, 2020-02)
    We used the data from the Fermi Gamma-ray Space Telescope to characterise the γ-ray flux variability of blazars on month-like time scales. Our sample consists of 1120 blazars of which 481 are flat spectrum radio quasars ...
  • Long-Term Monitoring of Blazar PKS 0208-512: A Change of γ-Ray Baseline Activity from EGRET to Fermi Era 
    Ammenadka, Krishna Mohana; Bhattacharya, Debbijoy; Bhattacharyya, Subir; Bhatt, N; Stalin, C. S (Multidisciplinary Digital Publishing Institute, 2022-10)
    The blazar PKS 0208-512 was in the lowest 𝛾 -ray brightness state during the initial 10 years of observations with the Fermi Gamma-ray Space Telescope (Fermi), which was an order of magnitude lower than its flux state ...
  • Long-term optical and infrared variability characteristics of Fermi blazars 
    Safna, P. Z; Stalin, C. S; Rakshit, S; Mathew, Blesson (Oxford University Press on behalf of the Royal Astronomical Society, 2020-11)
    We present long-term optical and near-infrared flux variability analysis of 37 blazars detected in the γ-ray band by the Fermi Gamma-Ray Space Telescope. Among them, 30 are flat spectrum radio quasars (FSRQs) and 7 are BL ...
  • Long-term optical flux and colour variability in quasars 
    Sukanya, N; Stalin, C. S; Jeyakumar, S; Praveen, D; Dhani, A; Damle, R (IOP Publishing, 2016-02)
    We have used optical V and R band observations from the Massive Compact Halo Object (MACHO) project on a sample of 59 quasars behind the Magellan ic clouds to study their long term optical flux and colour ...
  • Long-term ultraviolet variability of Seyfert galaxies 
    Sukanya, N; Stalin, C. S; Joseph, P; Rakshit, S; Praveen, D; Damle, R (Indian Academy of Sciences, 2018-12)
    Flux variability is one of the defining characteristics of Seyfert galaxies, a class of active galactic nuclei (AGN). Although these variations are observed over a wide range of wavelengths, results on their flux variability ...
  • Long-term ultraviolet variability of Seyfert galaxies 
    Sukanya, N; Stalin, C. S; Joseph, P; Rakshit, S; Praveen, D; Damle, R (Indian Academy of Sciences, 2018-12)
    Flux variability is one of the defining characteristics of Seyfert galaxies, a class of active galactic nuclei (AGN). Although these variations are observed over a wide range of wavelengths, results on their flux variability ...
  • Mass of the black hole in the Seyfert 1.5 galaxy H 0507+164 from reverberation mapping 
    Stalin, C. S; Jeyakumar, S; Coziol, R; Pawase, R. S; Thakur, S. S (Wiley-Blackwell, 2011-09)
    We present the results of our optical monitoring campaign of the X-ray source H 0507+164, a low-luminosity Seyfert 1.5 galaxy at a redshift z= 0.018. Spectroscopic observations were carried out during 22 nights in 2007, ...
  • Measurement of coronal properties of Seyfert galaxies from NuSTAR’s hard X-ray spectrum 
    Priyanka Rani; Stalin, C. S (Indian Academy of Sciences, 2018-02)
    Precise measurement of the coronal properties of Active Galactic Nuclei (AGN) requires the availability of high signal-to-noise ratio data covering a wide range of X-ray energies. The Nuclear Spectroscopic Telescope Array ...
  • Mid-infrared variability of γ-ray emitting blazars 
    Anjum, A; Stalin, C. S; Rakshit, S; Gudennavar, S. B; Durgapal, A (Oxford University Press on behalf of the Royal Astronomical Society, 2020-05)
    Using data from the Wide-field Infrared Survey Explorer, we studied the mid-infrared (mid-IR) 3.4 μm (W1-band) and 4.6 μm (W2-band) flux variability of γ-ray emitting blazars. Our sample consists of 460 flat spectrum radio ...

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