The compact UV nucleus of M33

The most luminous X-ray source in the Local Group is associated with the nu cleus of M33. This source, M33 X-8, appears modulated by similar to 20% ove r a similar to 106 day period, making it unlikely that the combined emissio n from unresolved sources could explain the otherwise persistent similar to 10(39) ergs s(-1) X-ray flux. We present here high-resolution UV imaging o f the nucleus with the Planetary Camera of the Hubble Space Telescope under taken in order to search for the counterpart to X-8. The nucleus is bluer a nd more compact than at longer wavelength images, but it is still extended, with half of its 3 x 10(38) ergs s(-1) UV luminosity coming from the inner 0." 14. We cannot distinguish between a concentrated blue population and e mission from a single object.