Sergey Nazarov

Sergey Nazarov
Crimean Astrophysical Observatory

About

80
Publications
11,061
Reads
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3,614
Citations
Introduction
Active galaxy nuclei: seyfert and blazars. Search new objects: variable stars, asteroids, comets, supernova and nova stars.
Additional affiliations
April 2019 - present
Crimean Astrophysical Observatory
Position
  • Researcher
March 2008 - March 2019
Crimean Astrophysical Observatory
Position
  • junior reseacher
February 2018 - present
Crimean pedagogical institute
Position
  • teacher
Description
  • astronomy teacher

Publications

Publications (80)
Preprint
Full-text available
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 flux and color variability results using data acquired in B, V, R, and I bands over a time span of $\sim$ 2 decades. We include data from WEBT collaborators and public archi...
Article
Full-text available
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 flux and color variability results using data acquired in B , V , R , and I bands over a time span of about two decades. We include data from WEBT collaborators and public a...
Preprint
We propose a new method for investigating the evolution of the properties of the blazar brightness variability on timescales from a few hours to a few days. Its essence lies in detecting sequentially located time intervals along the entire light curve, within which it is possible to determine the characteristic time of variability using the structu...
Article
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 data in the BVRI bands acquired at 36 observatories around the world. In mid-2021 the source showed its historical maximum, with R = 11.14. The light curves display many...
Preprint
Full-text available
Multiband optical photometry data of blazar S5 0716+714 obtained from 2002 to 2019 reveal stable color index change with flux variability. We analyzed this trend under variability caused by the Doppler factor change in the presence of a curved photon energy spectrum. A break in the energy spectrum of emitting electrons, caused by radiative losses,...
Article
Full-text available
In this contribution, we achieve the primary goal of the active galactic nucleus (AGN) STORM campaign by recovering velocity–delay maps for the prominent broad emission lines (Lyα, C IV, He II, and Hβ) in the spectrum of NGC 5548. These are the most detailed velocity–delay maps ever obtained for an AGN, providing unprecedented information on the ge...
Article
https://minorplanetcenter.net/mpec/K21/K21AJ0.html MPEC: 2021-A190
Conference Paper
The optical radiation of the blazar S5 0716+714 is formed within its ultrarelativistic jet in a compact region located near the true origin of the jet. Assuming that the variability is formed only by changing the relativistic radiation amplification coefficient (Doppler factor) for some part of the emitting region and that the spectrum of the emitt...
Conference Paper
For the interpretation of X-ray radiation from kiloparsec jets of quasars, the inverse Compton scattering of the cosmic microwave background has been widely used for almost 20 years. A recent analysis of the Fermi-LAT observational data showed that this assumption is inapplicable for jets of several quasars. In this paper, we consider the inverse C...
Preprint
Full-text available
For the interpretation of X-ray radiation from kiloparsec jets of quasars, the inverse Compton scattering of the cosmic microwave background has been widely used for almost 20 years. A recent analysis of the Fermi-LAT observational data showed that this assumption is inapplicable for jets of several quasars. In this paper, we consider the inverse C...
Article
Full-text available
For the interpretation of X-ray radiation from kiloparsec jets of quasars, the inverse Compton scattering of the cosmic microwave background has been widely used for almost 20 years. A recent analysis of the Fermi-LAT observational data showed that this assumption is inapplicable for jets of several quasars. In this paper, we consider the inverse C...
Article
Full-text available
We present geometric and dynamical modeling of the broad line region (BLR) for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The data set includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the Hβ, C iv, and Lyα broad emission lines. We find an extended disk-like Hβ BLR with...
Preprint
Full-text available
We present geometric and dynamical modeling of the broad line region for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The dataset includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the H$\beta$, C IV, and Ly$\alpha$ broad emission lines. We find an extended disk-like H$\bet...
Preprint
Full-text available
We report velocity-delay maps for prominent broad emission lines, Ly_alpha, CIV, HeII and H_beta, in the spectrum of NGC5548. The emission-line responses inhabit the interior of a virial envelope. The velocity-delay maps reveal stratified ionization structure. The HeII response inside 5-10 light-days has a broad single-peaked velocity profile. The...
Article
Full-text available
Gaia16aye was a binary microlensing event discovered in the direction towards the northern Galactic disc and was one of the first microlensing events detected and alerted to by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to I = 12 mag, and it was covered in great detail with almost 25 000 data p...
Article
Full-text available
We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013–2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as well a...
Preprint
Full-text available
We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013-2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as well a...
Article
Full-text available
We model the ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 obtained with the Hubble Space Telescope during the 6 month reverberation mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum va...
Preprint
We model the ultraviolet spectra of the Seyfert 1 galaxy NGC~5548 obtained with the Hubble Space Telescope during the 6-month reverberation-mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum va...
Preprint
Full-text available
Context: Gaia16aye was a binary microlensing event, the first such event ever discovered in the direction towards the Northern Galactic Disk and one of the first microlensing events detected and alerted by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to 11 mag, and was covered in great detail wit...
Article
Context: Gaia16aye was a binary microlensing event, the first such event ever discovered in the direction towards the Northern Galactic Disk and one of the first microlensing events detected and alerted by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to 11 mag, and was covered in great detail wit...
Preprint
Full-text available
The flat-spectrum radio quasar 4C $+$71.07 is a high-redshift ($z=2.172$), $\gamma$-loud blazar whose optical emission is dominated by the thermal radiation from accretion disc. 4C $+$71.07 has been detected in outburst twice by the AGILE $\gamma$-ray satellite during the period end of October - mid November 2015, when it reached a $\gamma$-ray flu...
Article
Full-text available
We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one active galactic nucleus (AGN) (NGC 3227) from a 2014 campaign. Our main goals are (1) to determine the black hole masses from continuum-Hβ reverberation signatures, and (2) to look for velocity-dependent time dela...
Preprint
Full-text available
We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one AGN (NGC 3227) from a 2014 campaign. Our main goals are (1) to determine the black hole masses from continuum-Hbeta reverberation signatures, and (2) to look for velocity-dependent time delays that might be indica...
Article
Full-text available
We present optical continuum lags for two Seyfert 1 galaxies, MCG+08-11-011 and NGC 2617, using monitoring data from a reverberation mapping campaign carried out in 2014. Our light curves span the ugriz filters over four months, with median cadences of 1.0 and 0.6 days for MCG+08-11-011 and NGC\,2617, respectively, combined with roughly daily X-ray...
Preprint
We present optical continuum lags for two Seyfert 1 galaxies, MCG+08-11-011 and NGC 2617, using monitoring data from a reverberation mapping campaign carried out in 2014. Our light curves span the ugriz filters over four months, with median cadences of 1.0 and 0.6 days for MCG+08-11-011 and NGC\,2617, respectively, combined with roughly daily X-ray...
Article
Full-text available
Blazar emission is dominated by non-thermal radiation from a relativistic jet pointing toward us, therefore undergoing Doppler beaming. This is responsible for flux enhancement and contraction of the variability time scales, so that most blazars appear as luminous sources characterized by noticeable and fast flux changes at all frequencies. The mec...
Article
Full-text available
Continuing the project described by Kato et al. (2009, PASJ, 61, S395), we collected times of superhump maxima for 127 SU UMa-type dwarf novae observed mainly during the 2016-2017 season and characterized these objects. We provide updated statistics of the relation between the orbital period and the variation of superhumps, the relation between per...
Article
Full-text available
During the Space Telescope and Optical Reverberation Mapping Project (STORM) observations of NGC 5548, the continuum and emission-line variability became de-correlated during the second half of the 6-month long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as a part of the campaign. The Swift spectra show...
Preprint
During the Space Telescope and Optical Reverberation Mapping Project (STORM) observations of NGC 5548, the continuum and emission-line variability became de-correlated during the second half of the 6-month long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as a part of the campaign. The Swift spectra show...
Article
We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved an almost daily cadence with observations from five ground-based telescopes. The H$\beta$ and He II $\lambda$4686 broad emission-line light curves...
Article
Full-text available
In 2015 July 29 – September 1 the satellite XMM-Newton pointed at the BL Lac object PG 1553+133 six times, collecting data for 218 hours. During one of these epochs, simultaneous observations by the Swift satellite were requested to compare the results of the X-ray and optical–UV instruments. Optical, near-infrared and radio monitoring was carried...
Preprint
We summarize results of the analysis of the optical variability of the continuum and emission-line fluxes in the 3C390.3 nucleus during 1992-2014. The [OIII]5007 flux increases monotonically by $\approx$30 per cent in 2003-2014. The narrow Balmer lines show similar monotonic increase, while the variability patterns of the [OI]6300 narrow line are c...
Article
We conduct a multiwavelength continuum variability study of the Seyfert 1 galaxy NGC 5548 to investigate the temperature structure of its accretion disk. The 19 overlapping continuum light curves (1158 to 9157 angstroms) combine simultaneous HST , Swift , and ground-based observations over a 180 day period from 2014 January to July. Light-curve var...
Preprint
We conduct a multiwavelength continuum variability study of the Seyfert 1 galaxy NGC 5548 to investigate the temperature structure of its accretion disk. The 19 overlapping continuum light curves (1158 to 9157 angstroms) combine simultaneous HST , Swift , and ground-based observations over a 180 day period from 2014 January to July. Light-curve var...
Article
Full-text available
We summarize results of the analysis of the optical variability of the continuum and emission-line fluxes in the 3C 390.3 nucleus during 1992–2014. The [O iii] λ5007 flux increases monotonically by ≈30 per cent in 2003–2014. The narrow Balmer lines show similar monotonic increase, while the variability patterns of the [O i] λ6300 narrow line are co...
Article
Full-text available
We present the first results from an optical reverberation mapping campaign executed in 2014, targeting the active galactic nuclei (AGN) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a "changing look" AGN and a broad-line radio galaxy. Based on continuum-H$\beta$...
Preprint
We present the first results from an optical reverberation mapping campaign executed in 2014, targeting the active galactic nuclei (AGN) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a "changing look" AGN and a broad-line radio galaxy. Based on continuum-H$\beta$...
Article
International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the Max Planck Institute for Radio Astronomy; Universities of Bonn and Cologne; Academy of Finland project [274477]; NASA Fermi GI grant [NNX11AQ03G]; Russian Foundation for Basic Research [13-02-12103, 14-02-31789]; RFBR [12-02-01237a]; UNAM DGAPA-PAPIIT [IN116211-3...
Article
ACCEPTED After several years of quiescence, the blazar CTA 102 underwent an exceptional outburst in 2012 September–October. The flare was tracked from gamma-ray to near-infrared frequencies, including Fermi and Swift data as well as photometric and polarimetric data from several observatories. An intensive GASP-WEBT collaboration campaign in optic...
Preprint
After several years of quiescence, the blazar CTA 102 underwent an exceptional outburst in 2012 September-October. The flare was tracked from gamma-ray to near-infrared frequencies, including Fermi and Swift data as well as photometric and polarimetric data from several observatories. An intensive GASP-WEBT collaboration campaign in optical and NIR...
Article
Full-text available
We present ground-based optical photometric monitoring data for NGC 5548, part of an extended multi-wavelength reverberation mapping campaign. The light curves have nearly daily cadence from 2014 January to July in nine filters ($BVRI$ and $ugriz$). Combined with UV data from the $Hubble$ $Space$ $Telescope$ and $Swift$, we confirm significant time...
Article
Full-text available
During an intensive Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) UV monitoring campaign of the Seyfert~1 galaxy NGC 5548 performed from 2014 February to July, the normally highly correlated far-UV continuum and broad emission-line variations decorrelated for ~60 to 70 days, starting ~75 days after the first HST/COS observation. Fo...
Preprint
During an intensive Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) UV monitoring campaign of the Seyfert~1 galaxy NGC 5548 performed from 2014 February to July, the normally highly correlated far-UV continuum and broad emission-line variations decorrelated for ~60 to 70 days, starting ~75 days after the first HST/COS observation. Fo...
Article
Over the past few years, several occasions of large, continuous rotations of the electric vector position angle (EVPA) of linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy gamma-ray flares and they have attracted considerable attention, as they could allow one to probe the magnet...
Preprint
Over the past few years, several occasions of large, continuous rotations of the electric vector position angle (EVPA) of linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy gamma-ray flares and they have attracted considerable attention, as they could allow one to probe the magnet...
Preprint
We present ground-based optical photometric monitoring data for NGC 5548, part of an extended multi-wavelength reverberation mapping campaign. The light curves have nearly daily cadence from 2014 January to July in nine filters (\emph{BVRI} and \emph{ugriz}). Combined with ultraviolet data from the \emph{Hubble Space Telescope} and \emph{Swift}, we...
Article
Full-text available
A multifrequency campaign on the BL Lac object PG 1553+113 was organized by the Whole Earth Blazar Telescope (WEBT) in 2013 April–August, involving 19 optical, two near-IR, and three radio telescopes. The aim was to study the source behaviour at low energies during and around the high-energy observations by the Major Atmospheric Gamma-ray Imaging C...
Article
Full-text available
A large reverberation mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hbeta 4861 and He II 4686 and a central black hole mass measurement of about 10 million solar masses, consistent with previous measurements. A very low level of variability during the monitoring campaign precluded meeting our original goal of rec...
Article
Full-text available
MPEC 2014-R69 available at Minor Planet Center.
Article
Full-text available
Since the launch of the Fermi satellite, BL Lacertae has been moderately active at γ-rays and optical frequencies until 2011 May, when the source started a series of strong flares. The exceptional optical sampling achieved by the GLAST-AGILE Support Program of the Whole Earth Blazar Telescope in collaboration with the Steward Observatory allows us...
Article
Full-text available
Quasar 3C 279 is known to exhibit episodes of optical polarization angle rotation. We present new, well-sampled optical polarization data for 3C 279 and introduce a method to distinguish between random and deterministic electric vector position angle (EVPA) variations. We observe EVPA rotations in both directions with different amplitudes and find...
Article
Full-text available
We present velocity-resolved reverberation results for five active galactic nuclei. We recovered velocity-delay maps using the maximum entropy method for four objects: Mrk 335, Mrk 1501, 3C 120, and PG 2130+099. For the fifth, Mrk 6, we were only able to measure mean time delays in different velocity bins of the Hβ emission line. The four velocity-...
Article
Full-text available
We present velocity-resolved reverberation results for five active galactic nuclei. We recovered velocity-delay maps using the maximum-entropy method for four objects: Mrk 335, Mrk 1501, 3C120, and PG2130+099. For the fifth, Mrk 6, we were only able to measure mean time delays in different velocity bins of the Hbeta emission line. The four velocity...
Article
Full-text available
We present the results from a detailed analysis of photometric and spectrophotometric data on five Seyfert 1 galaxies observed as a part of a recent reverberation mapping program. The data were collected at several observatories over a 140 day span beginning in 2010 August and ending in 2011 January. We obtained high sampling-rate light curves for...
Article
Full-text available
We present the first results from a detailed analysis of photometric and spectrophotometric data on the narrow-line Seyfert 1 galaxy Mrk 335, collected over a 120-day span in the fall of 2010. From these data we measure the lag in the He II 4686 broad emission line relative to the optical continuum to be 2.7 \pm 0.6 days and the lag in the H\beta 4...
Article
Full-text available
Since 2005, the blazar 3C 454.3 has shown remarkable flaring activity at all frequencies, and during the last four years it has exhibited more than one γ-ray flare per year, becoming the most active γ-ray blazar in the sky. We present for the first time the multi-wavelength AGILE, Swift, INTEGRAL, and GASP-WEBT data collected in order to explain th...
Article
Full-text available
Long-term monitoring data at five radio frequencies from 4.8 to 37 GHz obtained at the Crimean Astrophysical Observatory, Metsahovi Radio Observatory of Aalto University, and the University of Michigan Radio Astronomy Observatory are used to analyze variations of the flux of the Active Galactic Nucleus (AGN) 3C 454.3. The dynamical characteristics...
Article
Full-text available
We present further results of the optical observations of the 3C 390.3 nucleus undertaken at the Crimean Astrophysical Observatory since 1992. From the new data obtained in 2000–2007, we find differences in the responses of the Balmer emission lines to the optical continuum variations. Moreover, these responses (i.e. the relationship between line a...
Article
Full-text available
Based on our UBV RI observations and X-ray data from the RXTE satellite, we have investigated the variability of the galaxy NGC 7469 over the period 1995–2009. In 1995–2000, the optical brightness of the galactic nucleus changed almost by 1m in the U band. In 2000–2009, the amplitude of the optical variations was considerably lower. Regular X-ray o...
Article
Full-text available
We present the final results from a high sampling rate, multi-month, spectrophotometric reverberation mapping campaign undertaken to obtain either new or improved Hβ reverberation lag measurements for several relatively low-luminosity active galactic nuclei (AGNs). We have reliably measured the time delay between variations in the continuum and Hβ...
Article
Full-text available
Based on our UBVRI observations and X-ray data from the RXTE satellite we have investigated the variabilities of the Seyfert Galaxy 3C 120 over the period 1996-2008. (2 data files).
Article
Full-text available
We report a relation between radio emission in the inner jet of the Seyfert galaxy 3C 120 and optical continuum emission in this galaxy. Combining the optical variability data with multi-epoch high-resolution very long baseline interferometry observations reveals that an optical flare rises when a superluminal component emerges into the jet and its...