1. Multi-band Optical Variability of the TeV Blazar PG 1553+113 in 2019
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Dhiman, Vinit, Gupta, Alok C., Kurtanidze, Sofia O., Eglitis, I., Strigachev, A., Damljanovic, G., Wiita, Paul J., Gu, Minfeng, Gaur, Haritma, Vince, Oliver, Bachev, R., Bisen, D. P., Ibryamov, S., Ivanidze, R. Z., Jovanovic, Miljana D., Kurtanidze, Omar M., Nikolashvili, M. G., Semkov, E., Spassov, B., Stojanovic, M., Villarroel, Beatriz, Xu, Haiguang, and Zhang, Zhongli
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report the flux and spectral variability of PG 1553+113 on intra-night (IDV) to short-term timescales using BVRI data collected over 91 nights from 28 February to 8 November 2019 employing ten optical telescopes: three in Bulgaria, two each in India and Serbia, and one each in Greece, Georgia, and Latvia. We monitored the blazar quasi-simultaneously for 16 nights in the V and R bands and 8 nights in the V, R, I bands and examined the light curves (LCs) for intra-day flux and colour variations using two powerful tests: the power-enhanced F-test and the nested ANOVA test. The source was found to be significantly (> 99%) variable in 4 nights out of 27 in R-band, 1 out of 16 in V-band, and 1 out of 6 nights in I-band. No temporal variations in the colours were observed on IDV timescale. During the course of these observations the total variation in R-band was 0.89 mag observed. We also investigated the spectral energy distribution (SED) using B, V, R, and I band data. We found optical spectral indices in the range of 0.878+-0.029 to 1.106+-0.065 by fitting a power law to these SEDs of PG 1553+113. We found that the source follows a bluer-when-brighter trend on IDV timescales. We discuss possible physical causes of the observed spectral variability., Comment: 13 pages,8 figures, 7 tables, Accepted for publication in MNRAS
- Published
- 2022
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