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Browsing by Author "Goyal, A"

Browsing by Author "Goyal, A"

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  • Improved characterization of intranight optical variability of prominent AGN classes 
    Goyal, A; Gopal-Krishna; Wiita, P. J; Stalin, C. S; Sagar, R (Oxford University Press on behalf of the Royal Astronomical Society, 2013-10-21)
    The incidence of intranight optical variability (INOV) is known to differ significantly among different classes of powerful active galactic nuclei (AGN). A number of statistical methods have been employed in the literature ...
  • Intra-night optical variability of core dominated radio quasars: the role of optical polarization 
    Goyal, A; Gopal-Krishna; Wiita, P. J; Anupama, G. C; Sahu, D. K; Sagar, R; Joshi, S (EDP Sciences, 2012-08)
    Context. Rapid variations in optical flux are seen in many quasars and all blazars. The amount of variability in different classes of active galactic nuclei has been studied extensively but many questions remain unanswered. ...
  • Prolonged intranight optical quiescence of the classical BL Lac object PKS 0735+178 
    Goyal, A; Gopal-Krishna; Anupama, G. C; Sahu, D. K; Sagar, R; Britzen, S; Karazous, M; Aller, M. F; Aller, H. D (Astronomical Society of the Pacific, 2009-09)
    We report our extensive intranight optical monitoring of the well known low-energy peaked (LBL) BL Lac object PKS 0735+178. This long-term follow-up consists of R-band monitoring for a minimum duration of ˜ 4 hours, on 17 ...
  • Rapid optical variability of TeV blazars 
    Gopal-Krishna; Goyal, A; Joshi, S; Karthick, C; Sagar, R; Wiita, P. J; Anupama, G. C; Sahu, D. K (Wiley-Blackwell, 2011-09)
    In this first systematic attempt to characterize the intranight optical variability (INOV) of TeV-detected blazars, we have monitored a well-defined set of nine TeV blazars on total 26 nights during 2004–10. In this R- or ...
  • Recent results on crab nebula and Mkn-421 observations with TACTIC imaging element 
    Bhatt, N; Agarwal, N. K; Bhat, C. K; Bhattacharaya, S; Charagi, S. K; Chandra, P; Chauhan, N; Dhar, V. K; Goyal, A; Goyal, H. C; Kamath, K; Kaul, C. L; Kaul, I. K; Kaul, R. K; Kaul, S. K; Kaul, S. R; Sharma, M; Kothari, M; Kotwal, S. V; Koul, D. K; Koul, M. K; Rannot, R. C; Razdan, A. K; Sahaynathan, S; Sapru, M. L; Satyabhama, N; Tickoo, A. K; Venugopal, K; Yadav, K. K; Bhat, C. L (Astronomical Society of India, 2002)
    The results of our recent observational campaigns on the Crab Nebula and Mkn-421, carried out with the 349-pixel Imaging Element of the TACTIC array, are presented alongwith the details of the data analysis. Analysis of ...
  • A search for QPOs in the lazar OJ287: preliminary results from the 2015/2016 observing campaign 
    Zola, S; Valtonen, M; Bhatta, G; Goyal, A; Debski, B; Baran, A; Krzesinski, J; Siwak, M; Ciprini, S; Gopakumar, A; Jermak, H; Nilsson, K; Reichart, D; Matsumoto, K; Sadakane, K; Gazeas, K; Kidger, M; Piirola, V; Alicavus, F; Baliyan, K. S; Berdyugin, A; Boyd, D; Campas Torrent, M; Campos, F; Carrillo G-mez, J; Caton, D. B; Chavushyan, V; Dalessio, J; Dimitrov, D; Drozdz, M; Er, H; Erdem, A; Escartin Perez, A; Fallah Ramazani, V; Filippenko, A. V; Garcia, F; Gomez Pinilla, F; Maheswar, G; Haislip, J. B; Harmanen, J; Hudec, R; Hurst, G; Ivarsen, K. M; Jelinek, M; Joshi, A; Kagitan, M; Kaur, N; Keel, W. C; LaCluyze, A. P; Lee, B. C; Lindfors, E; Lozano de Haro, J; Moore, J. P; Mugrauer, M; Naves Nogues, R; Neely, A. W; Nelson, R. H; Ogloza, W; Okano, S; Pandey, J. C; Perri, M; Pihajoki, P; Poyner, G; Provencal, J; Pursimo, T; Raj, A; 29 others (Molecular Diversity Preservation International, 2016-12)
    We analyse the light curve in the R band of the blazar OJ287, gathered during the 2015/2016 observing season. We did a search for quasi-periodic oscillations (QPOs) using several methods over a wide range of timescales. ...
  • Stochastic modeling of multiwavelength variability of the classical BL Lac Object OJ 287 on timescales ranging from decades to hours 
    Goyal, A; Stawarz, L; Zola, S; Marchenko, V; Soida, M; Nilsson, K; Ciprini, S; Baran, A; Ostrowski, M; Wiita, P. J; Gopal-Krishna; iemiginowska, A; Sobolewska, M; Jorstad, S; Marscher, A; Aller, M. F; Aller, H. D; Hovatta, T; Caton, D. B; Reichart, D; Matsumoto, K; Sadakane, K; Gazeas, K; Kidger, M; Piirola, V; Jermak, H; Alicavus, F; Baliyan, K. S; Baransky, A; Berdyugin, A; Blay, P; Boumis, P; Boyd, D; Bufan, Y; Campas Torrent, M; Campos, F; Carrillo Gomez, J; Dalessio, J; Debski, B; Dimitrov, D; Drozdz, M; Er, H; Erdem, A; Escartin Perez, A; Fallah Ramazani, V; Filippenko, A. V; Gafton, E; Garcia, F; Godunova, V; Gomez Pinilla, F; Maheswar, G; Haislip, J. B; Haque, S; Harmanen, J; Hudec, R; Hurst, G; Ivarsen, K. M; Joshi, A; Kagitani, M; Karaman, N; Karjalainen, R; Kaur, N; Koziel-Wierzbowska, D; Kuligowska, E; Kundera, T; Kurowski, S; Kvammen, A; LaCluyze, A. P; Lee, B. C; Liakos, A; Lozano de Haro, J; Moore, J. P; Mugrauer, M; Naves Nogues, R; Neely, A. W; Ogloza, W; Okano, S; Pajdosz, U; Pandey, J. C; Perri, M; Poyner, G; Provencal, J; Pursimo, T; Raj, A; and 29 co-authors (IOP Publishing, 2018-08-20)
    We present the results of our power spectral density analysis for the BL Lac object OJ 287, utilizing the Fermi-LAT survey at high-energy γ-rays, Swift-XRT in X-rays, several ground-based telescopes and the Kepler satellite ...
  • Unusual optical quiescence of the classical BL Lac object PKS 0735+178 on intranight time scale 
    Goyal, A; Gopal-Krishna; Anupama, G. C; Sahu, D. K; Sagar, R; Britzen, S; Karouzos, M; Aller, M. F; Aller, H. D (Wiley Blackwell, 2009-07)
    We present the result of our extensive intranight optical monitoring of the well known low-energy peaked BL Lac (LBL) object PKS 0735+178. This long-term follow-up consists of $R$-band monitoring for a minimum duration of ...
  • Young stellar population and ongoing star formation in the H ii complex Sh2-252 
    Jose, J; Pandey, A. K; Samal, M. R; Ojha, D. K; Ogura, K; Kim, J. S; Kobayashi, N; Goyal, A; Chauhan, N; Eswaraiah, C (Oxford University Press on behalf of the Royal Astronomical Society, 2013-07-11)
    In this paper, an extensive survey of the star-forming complex Sh2-252 has been undertaken with an aim to explore its hidden young stellar population as well as to understand the structure and star formation history for ...

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