KINEMATICAL PROPERTIES OF THE MEMBERS OF HICKSON GROUP NO 90

We present here stellar radial velocity and velocity dispersion profil es along several position angles for the four members of Hickson's Com pact Group No. 90. In order to reach fainter light levels and to measu re the effects of tidal interactions on the kinematics, the data have been processed with a new vectorial adaptive filtering technique. We f ind that a strong, slow interaction is beginning to take place between NGC 7173 and NGC 7174 and that NGC 7176 is virtually undisturbed. The kinematical data can be used to put constraints on the geometry of th e encounter. NGC 7173 is closer to the observer than NG 7174, while th e latter is receding from the companion at a velocity of approximately 280 km s-1 stripping the outer regions of NGC 7173. At the same time, the outer regions of NGC 7174 are slowed with respect to the central ones by the tidal action of NGC 7174. According to previous findings, the MIL ratio for the individual galaxies in the group turns out to be about 30 divided-by 50% smaller than for field galaxies.