Optical Spectroscopy of SRG/eROSITA Objects with 2.5-m Telescope at the Caucasus Mountain Observatory of the SAI MSU

Based on observations with the new transient double-beam spectrograph (TDS) at the 2.5-m telescope of the Caucasus Mountain Observatory of SAI MSU, we have determined the types and found the redshifts for six new X-ray sources (four quasars and two galaxy clusters) detected by the SRG space observatory during the Lockman Hole observations at the eROSITA performance verification phase. We show that the TDS allows the spectra of objects ~20ᵐ to be taken in 2 h of observations with a signal-to-noise ratio higher than 5 and a resolution R~ 1500 . The types and redshifts of the objects determined from our spectroscopic observations agree well with the predictions based on photometric data using the SRGz automatic classification system.