PSR 51012- A 5.26-MS PULSAR IN A 14.5-H BINARY-SYSTEM(5307 )

We report the discovery of PSR J1012 + 5307, a 5.26-ms pulsar found du ring the course of a survey for short-period pulsars with the 76-m Lov ell radio telescope at Jodrell Bank. The pulsar is in a 14.5-h circula r orbit with a companion star of mass greater than or similar to 0.11 M(circle dot) , typical of a low-mass white dwarf. The dispersion meas ure of 9.0 cm(-3) pc suggests a distance of similar to 520 pc. This re latively small distance, together with a galactic latitude of 51 degre es, makes the binary system an excellent candidate for optical studies . Indeed, from an inspection of the Palomar sky survey plate, we have identified a 19th-magnitude star that lies well within the positional error box obtained from pulse arrival time measurements. If the star w ere the companion star to J1012 + 5307, then the age of the system wou ld be much smaller than the characteristic age of the pulsar would sug gest. Further optical observations of this system are required to conf irm this possibility.