Copernicus--X-ray Observations of 3U 0750 - 49

Based on the Uhuru survey, it has been suggested that there is an association between X-ray sources and bright stars (Gursky 1972). One such possible association is between 3U 0750 – 49 and the bright variable star V Pup. Because of their accessibility, we have observed these objects in both X-rays and ultraviolet with the Copernicus telescopes. We have analysed approximately five days worth of X-ray data from Copernicus on V Pup and HD 64740, two bright stars close to the relatively weak X-ray source 3U 0750 – 49. The X-ray source is almost certainly closer to V Pup than HD 64740 and the data do not completely exclude V Pup as a candidate with the confidence with which HD 64740 is ruled out. We derive an error box perpendicular to the 3U error box and of similar dimensions. Based on both error boxes the variable stars most likely to be the X-ray source are V Pup, CN Pup and CSV 1199.