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Browsing by Author "Gaur, Haritma"

Browsing by Author "Gaur, Haritma"

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  • Anti-correlated optical flux and polarization variability in BL Lac 
    Gaur, Haritma; Gupta, A. C.; Wiita, P. J.; Uemura, M.; Itoh, R.; Sasada, M. (2014)
    We present the results of photometric (V band) and polarimetric observations of the blazar BL Lac during 2008–2010 using TRISPEC attached to the KANATA 1.5 m telescope in Japan. The data reveal a great deal of variability ranging ...
  • Characterizing Optical Variability of OJ 287 in 2016–2017 
    Gupta, Alok C. et al.; Gaur, Haritma; Pandey, A. (The Astronomical Journal, 2019-03)
    We report on a recent multiband optical photometric and polarimetric observational campaign of the blazar OJ 287 that was carried out during 2016 September–2017 December. We employed nine telescopes in Bulgaria, China, ...
  • Intra-night optical flux and polarization variability of BL Lacertae during its 2020–2021 high state 
    Bachev, Rumen; Tripathi, Tushar; Gupta, Alok C.; Kishore, Shubham; Gaur, Haritma; Dhiman, Vinit (Monthly Notices of the Royal Astronomical Society, 2023-06)
    In this work, we report the presence of rapid intra-night optical variations in both flux and polarization of the blazar BL Lacertae during its unprecedented 2020–2021 high state of brightness. The object showed significant ...
  • Multiband optical variability of the TeV blazar PG 1553 + 113 in 2019 
    Dhiman, Vinit; Gupta, Alok C. ,et.al.; Gaur, Haritma (Monthly Notices of the Royal Astronomical Society, 2023-02)
    We report the flux and spectral variability of PG 1553 + 113 on intra-night (IDV) to short-term time-scales using BVRI data collected over 91 nights from 28 February to 8 November 2019 employing 10 optical telescopes: ...
  • Multiband optical variability on diverse time-scales of the TeV blazar TXS 0506 + 056, the first cosmic neutrino source 
    Dhiman, Vinit; Gupta, Alok C.; Bachev, Rumen; Wiita, Paul J.; Cellone, Sergio A.; Strigachev, A.; Gaur, Haritma; Darriba, A.; Bisen, D. P.; Locatelli, G.; Mammana, L. A.; Semkov, E. (Monthly Notices of the Royal Astronomical Society, 2024-01)
    We report the first extensive optical flux and spectral variability study of the TeV blazar TXS 0506 + 056 on intranight to long-term time-scales using BVRI data collected over 220 nights between 2017 January 21 to 2022 ...
  • Multiwavelength variability of the blazars Mrk 421 and 3c 454.3 in the high state 
    Gaur, Haritma; Gupta, A. C.; Wiita, P. J. (2012)
    We report the results of photometric observations of the blazars Mrk 421 and 3C 454.3 designed to search for intraday variability (IDV) and short-term variability (STV). Optical photometric observations were spread over 18 ...
  • Optical intraday variability of the blazar S5 0716+714 
    Tripathi, Tushar; Gupta, Alok C.; Takey, Ali; Bachev, Rumen; Vince, Oliver; Strigachev, Anton; Kushwaha, Pankaj; Elhosseiny, E. G.; Wiita, Paul J.; Damljanovic, G.; Dhiman, Vinit; Fouad, A.; Gaur, Haritma; Gu, Minfeng; Hamed, G. E.; Kishore, Shubham; Kurtenkov, A.; Rastogi, Shantanu; Semkov, E.; Zead, I.; Zhang, Zhongli (Monthly Notices of the Royal Astronomical Society, 2024-01)
    We present an extensive recent multiband optical photometric observations of the blazar S5 0716+714 carried out over 53 nights with two telescopes in India, two in Bulgaria, one in Serbia, and one in Egypt during 2019 ...
  • Optical variability of TeV blazars on long time-scales 
    Gaur, Haritma; Gupta, Alok C; Bachev, R. (Monthly Notices of the Royal Astronomical Society, 2019-02)
    We present the results of photometric observations of three TeV blazars, 3C 66A, S4 0954+658, and BL Lacertae (BL Lac), during the period 2013–2017. Our extensive observations were performed in a total of 360 nights which ...
  • Quasi-simultaneous Optical Flux and Polarization Variability of the Binary Super Massive Black Hole Blazar OJ 287 from 2015 to 2023: Detection of an Anticorrelation in Flux and Polarization Variability 
    Gupta, Alok C.; Kushwaha, Pankaj; Valtonen, Mauri J.; Savchenko, Sergey S.; Jorstad, Svetlana G.; Imazawa, Ryo; Wiita, Paul J.; Gu, Minfeng; Marscher, Alan P.; Zhang, Zhongli; Bachev, Rumen; Borman, G. A.; Gaur, Haritma; Grishina, T. S.; Hagen-Thorn, V. A.; Kopatskaya, E. N.; Larionov, V. M.; Larionova, E. G.; Larionova, L. V.; Morozova, D. A.; Nakaoka, T; Strigachev, A; Troitskaya, Yulia V.; Troitsky, I. S.; Uemura, M.; Vasilyev, A. A.; Weaver, Z. R.; Zhovtan, A. V. (Astrophysical Journal Letters, 2023-11)
    We study the optical flux and polarization variability of the binary black hole blazar OJ 287 using quasi simultaneous observations from 2015 to 2023 carried out using telescopes in the USA, Japan, Russia, Crimea, ...
  • Study of Intra-Day Flux Distributions of Blazars Using XMM-Newton Satellite 
    Wani, Kiran; Gaur, Haritma (Universe, 2022-11)
    We present a study of the flux distribution of a sample of 15 Intermediate and Low-energy peaked blazars using XMM-Newton observations in a total of 57 epochs on short-term timescales. We characterise the X-ray variability ...
  • X-Ray and Optical Studies of Blazars 
    Gaur, Haritma (ARIES, Nainital, 2013-02)
    Active Galactic Nuclei (AGN) are small regions in centers of some galaxies which emit powerful electromagnetic radiation, often outshining stars, gas, and dust which make up the host galaxy. These are the brightest ...
  • X-Ray Intraday Variability of the TeV Blazar Markarian 421 with XMM-Newton 
    Noel, A Priyana, et.al.; Gaur, Haritma; Gupta, Alok C.; Dhiman, Vinit (The Astrophysical Journal Supplement Series, 2022-09)
    Highly variable Markarian 421 is a bright high–synchrotron energy peaked blazar showing a wide featureless nonthermal spectrum, making it a good candidate for our study of intraday flux and spectral variations over time. We ...

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