In this paper, we present results of refining the characteristics of the eclipsing pre-cataclysmic variable SDSS J162256.6+473051 based on a model analysis of its optical radiation. We used the ...spectra of the system obtained with the 6-m BTA telescope of SAO RAS and the data from its multi-band photometric observations with the 1.5-m Russian-Turkish telescope RTT150. Calculations of the optical radiation of SDSS J162256.6+473051 were carried out using the method of irradiated atmosphere models. When analyzing the spectra of the system at the minimum brightness, we found the following atmospheric parameter estimates of the sdB sub-dwarf:
K,
, He/H
. The light curves of SDSS J162256.6+473051 were modeled and a complete set of fundamental parameters of the system was obtained. Their satisfactory agreement with the literature data allows us to conclude that the characteristics of similar systems with weak reflection effects can be analyzed together, even when they are determined using different methods of radiation modeling.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present the results of our long-term photometric and spectroscopic monitoring with the 1.5-m telescope RTT-150 for the optical counterpart of the high-mass X-ray binary IGR J21343+4738 discovered ...in 2002 by the INTEGRAL space X-ray observatory. The X-ray source was also repeatedly detected by the telescopes of the SRG observatory during the all-sky surveys in the period 2019–2021. We have investigated the spectroscopic and photometric variabilities of the optical counterpart, a Be star, caused by physical processes in the equatorial disk. The evolution of the equatorial disk parameters over a long time interval of 16 years has been analyzed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Based on a comparison of the SRG/eROSITA catalog of X-ray active stars and the Gaia catalog, we have obtained a sample of 502 peculiar objects for which Gaia, on the one hand, detects statistically ...significant parallaxes or proper motions and, on the other hand, records signs of a nonzero optical extent. On the
–color diagram these objects are significantly separated from the bulk of the stars and are located in the region typical for active galactic nuclei (AGNs). According to the SIMBAD database,
of them are AGNs and galaxies with spectroscopic redshifts and only
are confirmed objects in our Galaxy. Our spectroscopic observations of 19 unidentified objects with the RTT-150 telescope have shown that 18 of them are AGNs at redshifts
0.01–0.3 and one object is an M star in our Galaxy. We discuss various scenarios for the appearance of such peculiar objects.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present the results of our photometric and spectroscopic observations. We have studied four cataclysmic variable stars: 2XMM J183251.4-100106, MLS1809017 J224712+461815, MGAB-V330, and MGAB-V410. ...We have analyzed the observational data and determined the periods of the systems from our photometric data. The object MLS1809017 J224712+461815 has been classified as an SU UMa-type dwarf nova. The remaining three systems are eclipsing ones, with 2XMM J183251.4-100106 and MGAB-V410 showing signatures of polars. At the same time, for MGAB-V410 the orbital period
falls into the period gap for cataclysmic variables.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present the results of the optical identification and spectroscopic redshift measurements of 216 galaxy clusters detected in the SRG/eROSITA all-sky X-ray survey. The spectroscopic observations ...were performed in 2020–2023 with the 6-m BTA telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences, the 2.5-m telescope at the Caucasus Mountain Observatory of the Sternberg Astronomical Institute of the Moscow State University, the 1.6-m AZT-33IK telescope at the Sayan Solar Observatory of the Institute of Solar–Terrestrial Physics of the Siberian Branch of the Russian Academy of Sciences, and the 1.5-m Russian–Turkish telescope (RTT-150) at the TÜBİTAK Observatory. For all of the galaxy clusters presented here the spectroscopic redshift measurements have been obtained for the first time. Of these, 139 galaxy clusters have been detected for the first time in the SRG/eROSITA survey and 22 galaxy clusters are at redshifts
, including three at
. Deep direct images with the
rizJK
filters have also been obtained for four distant galaxy clusters at
. For these observations we chose the most massive clusters and, therefore, most of the galaxy clusters presented here with the spectroscopic redshifts measured by us will most likely enter in future into the cosmological samples of galaxy clusters from the SRG/eROSITA survey.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present the results of the optical identification, classification, and analysis of our photometric and spectroscopic observations of the X-ray transient SRGe J214919.3+673634 discovered by the ...eROSITA telescope onboard the Spectrum–Roentgen–Gamma orbital observatory in the summer of 2021 during the fourth sky survey. The photometric observations of the optical counterpart of SRGe J214919.3+673634 performed at the 6-m BTA telescope of SAO RAS, the 1.5-m Russian–Turkish telescope RTT-150, and the 2.5-m telescope of CMO SAI MSU as well the archival data from the 48-inch ZTF telescope have shown that the source is a cataclysmic variable with an orbital period
min and exhibits a long-term photometric variability from
(low state) to
(high state). We show that the light curves in the high state are consistent with the model of an accreting magnetized white dwarf and suggest that SRGe J214919.3+673634 belongs to the AM Her variables. The spectra of the optical counterpart taken in the low state at BTA are consistent with the spectral energy distribution of a white dwarf with a temperature
K.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Results of the first spectroscopic observations at the 1.5-m Russian–Turkish telescope for the X-ray sources discovered by the eROSITA telescope onboard the SRG space observatory and identified by ...the SRGz machine learning system as candidates for distant X-ray quasars are presented. Seven objects have been confirmed as quasars at redshifts
and two sources, which were included in the program of optical observations aimed at testing and adjusting SRGz and had a significant uncertainty in the photometric redshift, have turned out to be Seyfert galaxies at
.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present the results of our identification of eight objects from the preliminary catalogue of X-ray sources detected in the 4–12 keV energy band by the Mikhail Pavlinsky ART-XC telescope onboard ...the SRG observatory during the first all-sky survey. Three of them (SRGA J005751.0+210846, SRGA J
, SRGA J232446.8+440756) have been discovered by the ART-XC telescope, while five have already been known previously as X-ray sources, but their nature has remained unestablished. The last five sources have also been detected in soft X-rays by the eROSITA telescope of the SRG observatory. Our optical observations have been carried out at the 1.6-m AZT-33IK telescope of the Sayan Observatory and the 1.5-m Russian–Turkish telescope (RTT-150). All of the investigated objects have turned out to be active galactic nuclei (AGNs) at redshifts from 0.019 to 0.283. Six of them are Seyfert 2 galaxies (including one Seyfert 1.9 galaxy), one (SRGA J005751.0+210846) is a ‘‘hidden’’ AGN (in an edge-on galaxy), and one (SRGA J224125.9+760343) is a narrow-line Seyfert 1 galaxy. The latter object is characterized by a high X-ray luminosity (
erg s
in the 4–12 keV band) and, according to our black hole mass estimate (
), an accretion rate close to the Eddington limit. All three AGNs discovered by the ART-XC telescope (which are not detected by the eROSITA telescope) are characterized by a high absorption column density (
cm
). The results obtained confirm the expectations that the ART-XC telescope is an efficient instrument in searching for heavily obscured and other interesting AGNs in the nearby (
) Universe. The SRG sky survey will last for another 3 years or more, which must allow many such objects to be discovered.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present the results of spectroscopic redshift measurements for the galaxy clusters from the first all-sky Planck catalogue that have been mostly identified based on the optical observations ...performed previously by our team (Planck Collaboration 2015a). Data on 13 galaxy clusters at redshifts from
z
≈ 0.2 to
z
≈ 0.8, including the improved identification and redshift measurement for the cluster PSZ1 G141.73+14.22 at
z
= 0.828, are provided. We have performed the measurements based on data from the Russian–Turkish 1.5-m telescope (RTT-150), the 2.2-m Calar Alto Observatory telescope, and the 6-m SAO RAS telescope (Bolshoy Teleskop Azimutalnyi, BTA).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Results of the spectroscopic observations at the 1.5-m Russian–Turkish telescope for another group of 12 X-ray sources discovered by the eROSITA telescope onboard the SRG space observatory and ...identified by the SRGz machine learning system as candidates for distant X-ray quasars are presented. Ten objects have been confirmed as quasars at redshifts
and two sources have turned out to be active galactic nuclei (AGNs) at
and
.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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