ULTRAVIOLET-EXCESS SELECTION OF THE COUNTERPART TO A GLOBULAR-CLUSTERX-RAY BURSTER - HUBBLE-SPACE-TELESCOPE IMAGES OF THE CORE OF NGC-6712

Using the Planetary Camera on the Hubble Space Telescope, we have obta ined high spatial resolution, multicolor images and photometry of the core of the globular cluster NGC 6712. A comparison of our blue and ul traviolet images unambiguously reveals a faint (B almost-equal-to 21), UV-excess object, ''star S,'' within the Einstein error box for the b ursting x-ray source X1850-086. The unusual color of star S is immedia tely apparent even in a cursory visual comparison of the images, and i s more quantitatively (U-B approximately -1) confirmed via photometry. A variety of different candidate optical counterparts to the x-ray so urce have previously been suggested from ground-based work, but our im ages indicate that star S is almost certainly the only viable candidat e brighter than U almost-equal-to 21. Compared with the mean values fo r low mass x-ray binaries in the field, star S has a typical (U-B) col or, and a moderate-to-high x-ray-to-optical luminosity ratio, but its luminosity (M(B) almost-equal-to 5) is approximately 4 mag fainter tha n average.