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Intra-Night Variability of OJ 287 with Long-Term Multiband Optical Monitoring
Open AccessFeature PaperArticle

Multi-Band Intra-Night Optical Variability of BL Lacertae

Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China
Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263002, India
Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, 72 Tsarigradsko Shosse Blvd., 1784 Sofia, Bulgaria
Department of Physics, The College of New Jersey, P.O. Box 7718, Ewing, NJ 08628-0718, USA
Kavli Institute for Particle Astrophysics and Cosmology, SLAC, 2575 Sand Hill Rd, Menlo Park, CA 94025, USA
Department of Theoretical and Applied Physics, Faculty of Natural Sciences, University of Shumen, 115, Universitetska Str., 9712 Shumen, Bulgaria
Author to whom correspondence should be addressed.
Galaxies 2017, 5(4), 94;
Received: 30 October 2017 / Revised: 1 December 2017 / Accepted: 5 December 2017 / Published: 8 December 2017
(This article belongs to the Special Issue Microvariability of Blazars)
We monitored BL Lacertae frequently during 2014–2016 when it was generally in a high state. We searched for intra-day variability for 43 nights using quasi-simultaneous measurements in the B, V, R, and I bands (totaling 143 light curves); the typical sampling interval was about eight minutes. On hour-like timescales, BL Lac exhibited significant variations during 13 nights in various optical bands. Significant spectral variations are seen during most of these nights such that the optical spectrum becomes bluer when brighter. The amplitude of variability is usually greater for longer observations but is lower when BL Lac is brighter. No evidence for periodicities or characteristic variability time-scales in the light curves was found. The color variations are mildly chromatic on long timescales. View Full-Text
Keywords: active galaxies; BL Lacertae object: BL Lac; jets active galaxies; BL Lacertae object: BL Lac; jets
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Gaur, H.; Gupta, A.C.; Bachev, R.; Strigachev, A.; Semkov, E.; Wiita, P.J.; Gu, M.; Ibryamov, S. Multi-Band Intra-Night Optical Variability of BL Lacertae. Galaxies 2017, 5, 94.

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