A HIGH-FREQUENCY SURVEY OF THE SOUTHERN GALACTIC PLANE FOR PULSARS

We report the results of a high-frequency survey designed to detect young, distant and short-period pulsars. The Parkes 64-m radio telescope was used at a central observing frequency of 1500 MHz to survey an area of 800 square degrees in the region 270-degrees less-than-or-equal-to l less-than-or-equal-to 20-degrees, \b\ less-than-or-equal-to 4-degrees. To ensure that the system retained good sensitivity to periods of less than 10 ms, we used sampling intervals of 0.3 and 1.2 ms. The survey detected a total of 100 pulsars, 46 of which were previously unknown. The periods of the newly discovered pulsars range between 47 ms and 2.5 s. One of the new discoveries, PSR 1259-63, is a member of a long-period binary system. At least three of the pulsars have ages less than 30 000 yr, bringing the total number of such pulsars to 12. PSR 1112-60 is probably embedded in the powerful H II region RCW 57. The majority of the new discoveries are distant objects with high dispersion measures, which are difficult to detect at low frequencies. This demonstrates that the survey has reduced the severe selection effects of pulse scattering, high Galactic background temperature and dispersion broadening, which hamper the detection of such pulsars at low radio frequencies. This survey complements a similar survey of the northern Galactic plane undertaken by Clifton & Lyne. The pulsar distribution in the southern Galaxy is found to extend much further from the Galactic Centre than that in the north, probably due to two prominent spiral arms in the southern Galaxy.