Compressional Pc5 type pulsations in the morningside plasma sheet

We study compressional pulsations in Pc5 frequency range observed in the da wn-side at distances of about 10 R-E, close to the magnetic equator. We use data obtained during two events of conjunctions between Equator-S and Geot ail: 1000-1700 UT on 9 March 1998, and 0200-0600 UT on 25 April 1998. In bo th events, pulsations are observed after substorm activity. The pulsations are antisymmetric with respect to the equatorial plane (even mode), and mov e eastward with phase velocity close to plasma velocity. The pulsations ten d to be pressure balanced. We also discuss possible generation mechanisms o f the pulsations.