Pulsars

Abstract

The discovery of pulsars by astronomers at the University of Cambridge, England, during 1967 (Hewish et al., 1968) was one of the more exciting events in astronomy of recent years. The very unusual properties of these objects generated a great deal of effort on the part of both observational and theoretical astronomers. This resulted in the production of large amounts of observational data and numerous theories attempting to explain the observed properties. Searches for pulsars were instituted at many observatories around the world, with the result that the number of known pulsars grew rapidly from the original four discovered at Cambridge to over 100 known now. Many of these pulsars have been found by searching for bursts of strong pulses on records from a large radio-telescope equipped with a receiver sensitive to rapid input fluctuations. This technique has been particularly successful at the Molonglo Radio Observatory in Australia, where about 30 of the presently known pulsars have been discovered. Pulsars were not discovered earlier because in most radio astronomical observations, receivers have relatively long time constants to smooth out random noise fluctuations. Consequently these receivers do not respond to pulsar pulses.