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Spectroscopic Redshift Determination for a Sample of Distant Quasars Detected by the SRG Observatory Based on RTT-150 Observations. I


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 \(z=2.7{-}4.2\) 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 \(z\approx 0.6\).

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This work was supported by the subsidy (project no. 0671-2020-0052) allocated to the Kazan Federal University for the state assignment in the sphere of scientific activities. We are grateful to TÜBITAK, the Space Research Institute, the Kazan Federal University, and the Academy of Sciences of Tatarstan for their partial support in using RTT-150 (the Russian–Turkish 1.5-m telescope in Antalya). The calculations of the measurements of forced photometry based on WISE data for objects from the Pan-STARRS survey and the preparation of these data for the use in the SRGz algorithm were made with support by RSF grant no. 18-12-00520.

This work is based on observations with the eROSITA telescope onboard the SRG observatory. The SRG observatory was built by Roskosmos in the interests of the Russian Academy of Sciences represented by its Space Research Institute (IKI) within the framework of the Russian Federal Space Program, with the participation of the Deutsches Zentrum für Luft- und Raumfahrt (DLR). The SRG/eROSITA X-ray telescope was built by a consortium of German Institutes led by MPE, and supported by DLR. The SRG spacecraft was designed, built, launched, and is operated by the Lavochkin Association and its subcontractors. The science data are downlinked via the Deep Space Network Antennae in Bear Lakes, Ussurijsk, and Baykonur, funded by Roskosmos. The eROSITA data used in this work were processed using the eSASS software system developed by the German eROSITA consortium and the proprietary data reduction and analysis software developed by the Russian eROSITA Consortium. The SRGz system was created by the working group on the search for X-ray sources, their identification, and the production of a catalog based on eROSITA data at the Department of High-Energy Astrophysics of the Space Research Institute of the Russian Academy of Sciences.

The optical coordinates of the investigated sources from the GAIA DR2 catalog of the GAIA mission of the European Space Agency ( were retrieved using the Aladin Sky Atlas system developed at the Strasbourg Data Center, the Strasbourg Observatory, France.

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Correspondence to I. F. Bikmaev.

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Translated by V. Astakhov

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Bikmaev, I.F., Irtuganov, E.N., Nikolaeva, E.A. et al. Spectroscopic Redshift Determination for a Sample of Distant Quasars Detected by the SRG Observatory Based on RTT-150 Observations. I. Astron. Lett. 46, 645–657 (2020).

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  • quasars
  • active galactic nuclei
  • spectroscopy
  • SRG
  • RTT-150