6 papers
22 Newly Identified Repeating Changing-look AGNs and Evidence for Extreme Broad-line Region Breathing
Litao Zhu, Zhongxiang Wang, Alok C. Gupta +5
Changing-look active galactic nuclei (CL AGNs) show the appearance or disappearance of broad emission lines on timescales of years. Among them, the repeating CL (RCL) AGNs may prov…
Multi-band optical photometric variability of the blazar OJ 287 from 2015 to 2025
Alok C. Gupta, Karan Dogra, Mark Kidger +101
We present the most densely sampled multi-band optical photometric observations of the peculiar BL Lacertae object OJ 287 from 2015 to 2025 with a focus on its optical activity on…
Detection of optical quasi-periodic oscillation in the blazar 3C 454.3
Karan Dogra, Alok C. Gupta, C. M. Raiteri +83
We analyzed 19 years of -band data of the blazar 3C 454.3 from the Whole Earth Blazar Telescope (WEBT) archive, along with new data from its members and from public archives suc…
Multi-band optical variability of the blazar OP 313 in the outburst state during 2024-2025
P. U. Devanand, Alok C. Gupta, Karan Dogra +2
We present the analysis results of flux and spectral variability of the blazar OP 313 across intra-night to short-term timescales using BVRI photometric data, gathered over 25 nigh…
Testing Colour-magnitude Pattern as A Method in the Search for Changing-Look AGNs
Li-tao Zhu, Zhongxiang Wang, P. U. Devanand +6
We develop a simple method to search for changing-look (CL) active galactic nucleus (AGN) candidates, and conduct a test run. In this method, optical variations of AGNs are monitor…
Multiband Optical Variability of the Blazar 3C 454.3 on Diverse Timescales
Karan Dogra, Alok C. Gupta, C. M. Raiteri +79
Due to its peculiar and highly variable nature, the blazar 3C 454.3 has been extensively monitored by the WEBT team. Here, we present for the first time these long-term optical flu…