27 citations · 106 across the 11 of their papers we have counts for
12 papers
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…
Discovery of a Damped Ly Absorber in the Circumnuclear Zone of the FeLoBAL Quasar SDSS J083942.11+380526.3
Shengmiao Wu, Xiheng Shi, Nibedita Kalita +8
SDSS J083942.11+380526.3 () is a FeLoBAL quasar that exhibits visible Balmer absorption lines (H), implying a significant population. The quasar also shows an arr…
Intra-night optical flux and polarization variability of BL~Lacertae during its 2020 2021 high state
Rumen Bachev, Tushar Tripathi, Alok C. Gupta +15
In this work, we report the presence of rapid intra-night optical variations in both -- flux and polarization of the blazar BL Lacertae during its unprecedented 2020--2021 high sta…
Optical flux and spectral variability of BL Lacertae during its historical high outburst in 2020
Nibedita Kalita, Yuhai Yuan, Minfeng Gu +9
BL Lacertae had undergone a series of historical high flux activity over a year, from August 2020 in the optical to VHE -rays. In this paper, we report on optical flux and spect…
Optical variability of a newly discovered blazar sample from the BZCAT Catalog
Nibedita Kalita, Alok C. Gupta, Minfeng Gu
In an optical monitoring program to characterize the variability properties of blazar, we observed 10 sources from the Roma-BZCAT catalogue for 26 nights in V and R bands during Oc…
Blazar OJ 287 After First VHE Activity: Tracking the Re-emergence of the HBL like Component in 2020
Pankaj Kushwaha, Main Pal, Nibedita Kalita +5
We report the re-emergence of a new broadband emission through a detailed and systematic study of the multi-wavelength spectral and temporal behavior of OJ 287 after its first-ever…
Temporal and Spectral Variability of OJ 287 before the April--June 2020 Outburst
Nibedita Kalita, Alok C. Gupta, Minfeng Gu
We present the results of a temporal and spectral study of the BL Lacertae object OJ 287 in optical, UV, and X-ray bands with observations performed by Swift satellite during Septe…
Signature of stochastic acceleration and cooling processes in an outburst phase of the TeV blazar ON 231
Nibedita Kalita, Utane Sawangwit, Alok C. Gupta +1
We present a detailed spectral and temporal study of the intermediate-type blazar ON 231 during the TeV outburst phase in 2008 June with observations performed by Swift and XMM-New…
Swift and XMM-Newton monitoring of the ISP blazar ON 231 in outburst state
Nibedita Kalita, Utane Sawangwit
We present a detailed temporal and spectral study of the intermediate type blazar, ON 231 with observations taken by Swift and XMM-Newton satellites during an outburst phase in Jun…
Origin of X-rays in the low state of the FSRQ 3C 273: Evidence of inverse Compton emission
Nibedita Kalita, Alok C. Gupta, Paul J. Wiita +2
We analyze the 2.5--10 keV X-ray spectra of the luminous quasar 3C 273 and simultaneous observations in UV wavelengths from XMM--Newton between 2000 and 2015. The lowest flux level…
Peak of spectral energy distribution play an important role in intra-day variability of Blazars?
Alok C. Gupta, Nibedita Kalita, Haritma Gaur +1
Blazars can be divided into two sub-classes namely high energy and low energy peaked blazars. In spectral energy distribution, the first synchrotron hump of the former class peaks…
Multi-band variability in the blazar 3C 273 with XMM-Newton
Nibedita Kalita, Alok C. Gupta, Paul J. Wiita +2
We have undertaken a nearly simultaneous optical/UV and X-ray variability study of the flat spectrum radio quasar, 3C 273 using data available from the XMMNewton satellite missi…