143 citations · 896 across the 61 of their papers we have counts for
63 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…
Multi-wavelength picture of the misaligned BL Lac object 3C 371
J. Otero-Santos, C. M. Raiteri, A. Tramacere +52
The BL Lac object 3C 371 is one of the targets that are regularly monitored by the Whole Earth Blazar Telescope (WEBT) Collaboration to study blazar variability on both short and l…
Optical variability of the blazar 3C 371: from minute to year timescales
J. Otero-Santos, C. M. Raiteri, J. A. Acosta-Pulido +41
The BL Lac object 3C 371 has been observed by the Transiting Exoplanet Survey Satellite (\textit{TESS}) for approximately a year, between July 2019 and July 2020, with an unmatched…
The variability patterns of the TeV blazar PG 1553+113 from a decade of MAGIC and multi-band observations
MAGIC Collaboration, H. Abe, S. Abe +264
PG 1553+113 is one of the few blazars with a convincing quasi-periodic emission in the gamma-ray band. The source is also a very high-energy (VHE; >100 GeV) gamma-ray emitter. To b…
Photometric monitoring of PMS stars with the telescopes at Rozhen Observatory
Evgeni Semkov, Sunay Ibryamov, Stoyanka Peneva +1
For several decades we have been performing photometric monitoring of some of the star formation regions. Significant place in our program take observations of objects of the type…
Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and -ray brightness levels
C. M. Raiteri, M. Villata, M. I. Carnerero +64
In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and -ray bands. We present optical photometri…
Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES~2344+514
H. Abe, S. Abe, V. A. Acciari +232
The BL Lac 1ES 2344+514 is known for temporary extreme properties (e.g., a shift of the synchrotron SED peak energy above 1keV). While those extreme states were so fa…
Study of the long-term photometric variability of eight PMS stars in the young open cluster Trumpler 37
Sunay Ibryamov, Gabriela Zidarova, Evgeni Semkov +1
This paper reports results from our long-term photometric CCD observations of eight pre-main-sequence stars collected from June 2008 to October 2022. These stars are l…
The optical behaviour of BL Lacertae at its maximum brightness levels: a blend of geometry and energetics
C. M. Raiteri, M. Villata, S. G. Jorstad +13
In 2021 BL Lacertae underwent an extraordinary activity phase, which was intensively followed by the Whole Earth Blazar Telescope (WEBT) Collaboration. We present the WEBT optical…
Multi-band Optical Variability of the TeV Blazar PG 1553+113 in 2019
Vinit Dhiman, Alok C. Gupta, Sofia O. Kurtanidze +20
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 201…
Long-term Photometric Study of the Pre-main Sequence Star V1180 Cas
Asen Mutafov, Evgeni Semkov, Stoyanka Peneva +1
In this paper results from the optical photometric observations of the pre-main-sequence star V1180 Cas are reported. The star is a young variable associated with the dark cloud Ly…
Long-term optical photometry of the PMS stars V2764 Ori and LkH 301 in the field of the McNeil's Nebula
G. Zidarova, S. Ibryamov, E. Semkov +1
In this paper, we present results from long-term photometric observations of the pre-main-sequence stars V2764 Ori and LkH 301, located in the field of the McNeil's…
The FUor star V2493 Cyg (HBC 722) -- eleven years at maximum brightness
Evgeni Semkov, Sunay Ibryamov, Stoyanka Peneva
At the time of stellar evolution, young stellar objects go through processes of increased activity and instability. Star formation takes place in several stages during which the st…
Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017
MAGIC Collaboration, V. A. Acciari, S. Ansoldi +284
We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux co…
Long-term optical photometric monitoring of the FUor star V900 Mon
Evgeni Semkov, Stoyanka Peneva, Sunay Ibryamov
We present results from photometric monitoring of V900 Mon, one of the newly discovered and still under-studied object from FU Orionis type. FUor phenomenon is very rarely observed…
New Results from Long-time Photometric Study of UX Orionis Star GM Cephei
Asen Mutafov, Evgeni Semkov, Stoyanka Peneva +1
New results from long-term optical photometric observations of the pre-main sequence star GM Cep from UX Orionis type are reported. During ongoing photometric monitoring of the GM…
Long-term CCD photometry of pre-main-sequence stars in the association Cepheus OB3
Sunay Ibryamov, Gabriela Zidarova, Evgeni Semkov +1
Results from optical CCD photometric observations of 13 pre-main-sequence stars collected during the period from February 2007 to November 2020 are presented. These stars are locat…
A new prolonged decrease event in the brightness of the young stellar object V2492 Cygni
Sunay Ibryamov, Evgeni Semkov
Results from the BV(RI)c photometric observations of the young stellar object V2492 Cyg collected in the period from April 2018 to September 2020 are presented. These observations…
Multi-Wavelength Variability of BL Lacertae Measured with High Time Resolution
Zachary R. Weaver, K. E. Williamson, S. G. Jorstad +54
In an effort to locate the sites of emission at different frequencies and physical processes causing variability in blazar jets, we have obtained high time-resolution observations…
BV(RI)c photometric study of three variable PMS stars in the field of V733 Cephei
Sunay Ibryamov, Evgeni Semkov, Stoyanka Peneva +1
This paper report results from the first long-term BV(RI)c photometric CCD observations of three variable pre-main-sequence stars collected during the period from February 2007 to…
Intra-night flickering of RS Ophiuchi: III. Modes of quasi-periods in the minute scale and their evolution
Ts. B. Georgiev, R. K. Zamanov, S. Boeva +7
We study the photometric behavior of the recurrent nova RS Oph by 58 monitoring light curves (LCs), taken by 5 telescopes. All LCs show repeating time structures with some quasi-pe…
Unravelling the complex behavior of Mrk 421 with simultaneous X-ray and VHE observations during an extreme flaring activity in April 2013
MAGIC collaboration, V. A. Acciari, S. Ansoldi +237
We report on a multi-band variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 2013 April 19. The study…
Multiwavelength behaviour of the blazar 3C279: decade-long study from -ray to radio
V. M. Larionov, S. G. Jorstad, A. P. Marscher +84
We report the results of decade-long (2008-2018) -ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, and data, as well as polarim…
International observational campaign of the 2014 eclipse of EE Cep
D. Pieńkowski, C. Gałan, T. Tomov +64
Context. EE Cep is one of few eclipsing binary systems with a dark, dusty disk around an invisible object similar to ε Aur. The system is characterized by grey and asymmetric eclip…