Redshift Measurements for Galaxies in Clusters by Multislit Spectroscopy at the 1.5-m Telescope RTT150

An example of simultaneous spectroscopic redshift measurements for a large number of galaxies in a cluster by multiobject spectroscopy with the medium- and low-resolution TFOSC spectrograph at the RussianTurkish 1.5-m telescope (RTT150) is presented. The redshifts of galaxies in the cluster at detected previously by the SunyaevZeldovich signal in the Planck all-sky survey have been measured. The spectra of 16 cluster galaxies, 9 of which were determined as ellipticals, were taken in one observation with an exposure time of 3 h and high-quality redshift measurements were made for them. We show that the redshifts of galaxies with magnitudes to , whose number in the TFOSC field can reach dozens, depending on the cluster richness and distance, can be measured in one observation with the TFOSC spectrograph using multiobject masks. Such measurements may be required to refine the redshifts of clusters and to estimate their masses by the dynamical method.