2015/06/01 by Aditi Agarwal, Alok C. Gupta, R. Bachev +13 · 32 citations
Engineering · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Band-pass filter #Blazar #Flux (metallurgy) #Galaxy #Light curve #Optics #Passband #Photometry (optics) #Physics #Quasar #Radio Astronomy Observations and Technology #Radio Wave Propagation Studies #Range (aeronautics) #Spectral line #Spectral slope #Wavelength #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stv1208
published in Monthly Notices of the Royal Astronomical Society 451(4), 3882-3897 (Oxford University Press) · Accepted for publication in MNRAS, 16 pages, 11 figures, 5 tables, plus supplementary material containing additional figures and tables (please contact authors for it)
arxiv created 2015/06/01 · openalex publication_date 2015/06/29 · arxiv updated 2015/08/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
To search for optical variability on a wide range of time-scales, we have carried out photometric monitoring of two flat spectrum radio quasars, 3C 454.3 and 3C 279, plus one BL Lac, S5 0716+714, all of which have been exhibiting remarkably high activity and pronounced variability at all wavelengths. CCD magnitudes in B, V, R, and I passbands were determined for ∼7000 new optical observations from 114 nights made during 2011–2014, with an average length of ∼4 h each, at seven optical telescopes: four in Bulgaria, one in Greece, and two in India. We measured multiband optical flux and colour variations on diverse time-scales. Discrete correlation functions were computed among B, V, R, and I observations, to search for any time delays. We found weak correlations in some cases with no significant time lags. The structure function method was used to estimate any characteristic time-scales of variability. We also investigated the spectral energy distribution of the three blazars using B, V, R, I, J, and K passband data. We found that the sources almost always follow a bluer-when-brighter trend. We discuss possible physical causes of the observed spectral variability.