45 citations · 239 across the 21 of their papers we have counts for
21 papers
Is Mira B a low mass white dwarf?
R. K. Zamanov, V. Irincheva, B. Spassov +8
We report photometric observations in Johnson B and V bands of the short term variability (flickering) of Mira (omicron Ceti). The observations were performed during 7 nights in th…
Optical Photometric Monitoring of the Blazar OT 355 and Local Standard Stars' Calibration
R. Bachev, Tushar Tripathi, Alok C. Gupta +11
OT 355 (4FGL J1734.3 + 3858) is a relatively rarely studied but highly variable, moderate-redshift (z = 0.975) flat-spectrum radio quasar (blazar). With this work, we aim to study…
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…
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…
The hidden symbiotic star SU Lyn -- detection of flickering in U band
R. K. Zamanov, A. Kostov, M. Moyseev +18
We report photometric observations of the hidden symbiotic star SU Lyn in the optical bands. In five nights we detect a weak flickering in U band with amplitude of about 0.05 magni…
A Long-Term Spectral Study of the Single Active Giant OP Andromedae
Stefan Georgiev, Renada Konstantinova-Antova, Ana Borisova +10
We present a spectral study of the single magnetically active K giant OP And in the period 1979 -- 2018, monitoring the variability of the activity indicator line H. Original da…
Flickering of the jet-ejecting symbiotic star MWC 560
R. K. Zamanov, S. Boeva, K. A. Stoyanov +4
We analyse optical photometric data of short term variability (flickering) of the accreting white dwarf in the jet-ejecting symbiotic star MWC560. The observations are obtained in…
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…
Colours of the flickering source of Mira
R. Zamanov, S. Boeva, B. Spassov +3
We report photometric observations in Johnson UBV bands of the short term variability of Mira. The amplitude detected is 0.16 mag in B band. Adopting interstellar extinction E(B-V)…
Intra-night flickering of RS Ophiuchi: I. Sizes and cumulative energies of time structures
Ts. B. Georgiev, R. K. Zamanov, S. Boeva +7
We analyzed 29 pairs of time series in B and V bands of the recurrent nova RS Oph. The observations were carried out in 2008-2017 with duration 0.6 - 3.6 hours, with time resolutio…
The recurrent nova RS Oph - simultaneous B and V band observations of the flickering variability
R. K. Zamanov, S. Boeva, G. Y. Latev +7
We performed 48.6 hours (in 28 nights) of simultaneous B and V band observations of the flickering variability of the recurrent nova RS Oph in quiescence. During the time of our ob…
The Bright -ray Flare of 3C 279 in June 2015: AGILE Detection and Multifrequency Follow-up Observations
C. Pittori, F. Lucarelli, F. Verrecchia +44
We report the AGILE detection and the results of the multifrequency follow-up observations of a bright -ray flare of the blazar 3C 279 in June 2015. We use AGILE-GRID and Fermi-…
Photopolarimetrical Study of Blazar-type AGN OJ287 in 2012-2015 with the 2m RCC Telescope at NAO Rozhen
Vladimir Bozhilov, Evgeni Ovcharov, Milen Minev +6
We present the results of a photopolarimetric study of the blazar OJ287 in the period November 2012-January 2015. Observations were conducted using the Focal Reductor FoReRo-2 of t…
Intra-night variability of the blazar CTA 102 during its 2012 and 2016 giant outbursts
R. Bachev, V. Popov, A. Strigachev +6
We obtained and analyzed more than 100 hours of multicolour optical time series of the blazar CTA 102 during its 2012 and 2016 outbursts. The object reached almost 11-th mag at the…
Multiband optical variability of the blazar OJ 287 during its outbursts in 2015 -- 2016
Alok C. Gupta, A. Agarwal, A. Mishra +31
We present recent optical photometric observations of the blazar OJ 287 taken during September 2015 -- May 2016. Our intense observations of the blazar started in November 2015 and…
The Extremes in Intra-Night Blazar Variability: The S4 0954+65 Case
Rumen Bachev, Anton Strigachev, Evgeni Semkov +4
We present results of optical observations of the extremely violently variable blazar S4 0954+65 on intra-night time scales. The object showed flux changes of up to 100% within a f…
Multi-band optical variability of the Blazar S5 0716+714 in outburst state during 2014-2015
Aditi Agarwal, Alok C. Gupta, R. Bachev +7
We analyzed the multi-band optical behaviour of the BL Lacertae object, S5 0716+714, during its outburst state from 2014 November - 2015 March. We took data on 23 nights at three o…
Optical Flickering of the recurrent nova RS Ophiuchi: amplitude - flux relation
R. Zamanov, G. Latev, S. Boeva +7
We report observations of the flickering variability of the symbiotic recurrent nova RS~Oph at quiescence in five bands (). We find evidence of a correlation between the pea…
Photometric reverberation mapping of Markarian 279
R. Bachev, A. Strigachev, E. Semkov +9
By using standard broad-band VRI photometry we were able to discriminate the variations of the broad hydrogen alpha line from the continuum variations for the active galaxy Mkn 279…
Simultaneous UBVRI observations of the cataclysmic variable AE Aquarii: temperature and mass of fireballs
R. K. Zamanov, G. Y. Latev, K. A. Stoyanov +3
We report simultaneous multicolour observations in 5 bands (UBVRI) of the flickering variability of the cataclysmic variable AE Aqr. Our aim is to estimate the parameters (colours,…
Short Term Flux and Colour Variations in Low-Energy Peaked Blazars
Bindu Rani, Alok C. Gupta, A. Strigachev +11
We have measured multi-band optical flux and colour variations for a sample of 12 low energy peaked blazars on short, day-to-month, timescales. Our sample contains six BL Lacertae…