PROPER MOTION STUDY OF THE GLOBULAR-CLUSTER M-92

We present proper motions for stars in the field of the galactic gIobu lar cluster NGC 6341 (M 92), This study continues the series of papers from the Bonn programme of globular cluster proper motions. Plates ta ken with the Bonn double refractor and the Rozhen observatory 2m Ritch ey-Chretien telescope with a maximal epoch difference of 94 years were used. Relative proper motions for all well-measurable stars in the 1. 5 degrees x 1.5 degrees field covered by the plates were derived. Medi an proper motion errors are 0.8 milliarcsec/year (mas/a) for stars bri ghter than about V = 16.7m. Tile cluster membership of W-bright and va riable stars is discussed. The proper motions an compared with the acc urate relative proper motions of Pees (1992) and with the absolute pro per motions from Schmidt plates referred to galaxies of Scholz ct al. (1994). The latter comparison enables us to lie the proper motions of tile stars and the mean proper motion of M 92 to an inertial system, T his calibration has an uncertainty of about 1.0 mas/a. The absolute pr oper motions of Hipparcos stars in the field will be useful for the ex tragalactic calibration of the Hipparcos proper motion system. The dat a for 642 stars within 18.6' from the cluster centre is available via the CDS (Centre des Donnees Astronomiques Strasbourg) Data Centre.