1. Multiband optical variability of the TeV blazar PG 1553 + 113 in 2019.
- Author
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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, and Stojanovic, M
- Subjects
SPECTRAL energy distribution ,BL Lacertae objects ,OPTICAL telescopes ,LIGHT curves ,ACTIVE galaxies - Abstract
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: 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 per cent) 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 time-scale. 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 (F
ν ∝ν−α ) to these SEDs of PG 1553 + 113. We found that the source follows a bluer-when-brighter trend on IDV time-scales. We discuss possible physical causes of the observed spectral variability. [ABSTRACT FROM AUTHOR]- Published
- 2023
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