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Session 111 - Pulsars.
Display session, Saturday, January 10
Although the locations of over 600 pulsars are known today, their birthplaces remain somewhat of an enigma. It has been conjectured by Narayan and Ostriker (1990) that there are two different types of pulsars in the Galaxy, one born near the Galactic plane and a second born high above the plane with large velocities. The existence of two distinct subpopulations would account for the observations by Harrison, Lyne, and Anderson (1993) of four pulsars with velocities toward the Galactic plane. Thirteen of the 31 pulsars in our group have been observed at two epochs at 20 cm at the VLA in Socorro, New Mexico. This pulsar data is unique in that it was taken at the VLA using a "matched filter." The pulsar was detected using the Princeton Mark III Timing Machine and the correlator was then gated with the correct phase so that it only gathered data when the pulsar was "on." By gating our data, we have been able to increase the signal to noise ratio of weak pulsars by a factor of six. This increased SNR enables us to accurately determined positions for pulsars as weak as 2 mJy in the ungated data. By doubling the number of pulsars high above the Galactic plane with measured proper motions, we will be able to improve our understanding of the birth and evolution of the pulsar population.
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