Observations of Ionized Gas around Active Galaxies at the 2.5-m CMO SAI MSU Telescope

MaNGaL (Mapper of Narrow Galaxy Lines) is a tunable filter narrow-band photometer installed at the 2. 5-m telescope of the Caucasian Mountain Observatory of the Sternberg Astronomical Institute at Lomonosov Moscow State University (CMO SAI MSU). It enables us to detect and study the gas clouds, ionized by UV-radiation from an active galactic nucleus (AGN). We present a brief overview of MaNGaL observations of various manifestations of AGN ionization cones: tracking of fading nuclear activity in merging galaxies; the cross-ionization of disc companion of galaxies; the discovery of a complex system of external emission filaments near the NGC 1142/1144, the first OIII map of a rare type of objects known as ‘‘green beans, ’’ characterized by powerful, extended ionization cones at redshifts z=0. 2-0. 4.