Submicrosecond time resolution observations of PSR0950 + 08

Abstract

PULSARS were discovered by Hewish et al.¹ using an instrument with higher time resolution than was conventionally used in radioastronomy. From the short time duration pulses they detected they placed an upper limit of 4.8 × 10³ km on the size of the objects, assuming that a radiating region producing a pulse of duration t cannot be larger than ct, the distance light can travel during the pulse. Other observers^2–5 have since reduced this size limit with improved time resolution, with the objective of determining the size of the fundamental radiating elements. We report here our observations of isolated unresolved 0.8 µs micropulses, which, if the conventional assumption is made, result from emitting volumes less than 250 m in extent. We also show that even with our high time resolution the observations are consistent with Rickett's amplitude modulated noise model⁶ for pulsar emission, where all of the observed intensity fluctuations can be represented as the modulation of a more fundamental gaussian noise process.