ROSAT high resolution imager observations of PSR 0656+14

We have used the High Resolution Imager (HRI) on ROSAT to image PSR 0656+14 at soft X-ray energies (0.15-2 keV). With a net observing time of 10,326 s, we obtained a source event rate of 0.382 ± 0.007 counts s^-1. Comparing the radial distribution of these counts between 15″ and 100″ to an empirically derived point spread function for HRI soft sources, we find no evidence of a spatially extended X-ray nebula to a limiting surface brightness of 1.67 × 10^-6 counts s^-1 arcsec^-2, corresponding to a limit of 14% of the observed flux out to a radius of 100″. The X-ray emission of the pulsar is pulsed at the 0.385 s period of the radio pulsar, with a pulse fraction of 7% ± 2.2%, and a FWHM of 0.10 s. We discuss some models of the X-ray radiation of PSR 0656+14 compatible with both the HRI and PSPC results.