ASTROMETRY OF THE GLOBULAR-CLUSTER 47-TUCANAE AND POSSIBLE OPTICAL-IDENTIFICATION OF X-RAY SOURCES

Positions of stars of 47 Tuc have been derived by the use of photograp hic plates and CCD frames (ESO La Silla) and data from the Hubble Spac e Telescope (HST). The positions have been determined with respect to the PPM, which is based on the FK5 system. We have compared the positi ons of variable and blue stars in the core of 47 Tuc with those of the X-ray sources found by Hasinger et al. (1994). Taking into account a possible constant shift of the X-ray positions of up to 10 '', there a re three different solutions which would give identifications of four of the central X-ray sources with blue stragglers and variable stars. We discuss the nature of the X-ray sources and the different possible identifications. Since it is not possible to give a unique identificat ion based on pure astrometric arguments, our positions may be taken fo r future identifications based on additional astrophysical arguments o r coincident observations in different wavelengths. An identification of the X-ray source No. 3 of Hasinger et al. (1994) in the outer field of 47 Tuc with a galaxy was found.