ABSOLUTE PROPER MOTION AND SPACE MOTION OF THE GLOBULAR-CLUSTER M15

We have separated cluster members and field stars for stars in a regio n around the globular cluster M15. The membership of ultraviolet brigh t stars of M 1 5 is discussed. The absolute proper motion of M15 has b een determined with respect to the PPM catalogue. An extragalactic cal ibration of the proper motions has been performed. The calibration was done by measurements of galaxies on the Palomar Sky Survey glass copi es and plates from the Schmidt telescope of the Observatoire de la Cot e d'Azur (CERGA). We compare the three different methods of establishi ng absolute proper motion for the globular cluster M15. The orbital pa rameters of M 1 5 have been derived. As a by-product of our work, we o btained for eight stars of the HIPPARCOS input catalogue absolute prop er motions, which may be used for the calibration of the HIPPARCOS pro per motion system.