GINGA OBSERVATIONS OF THE OLD NOVA GK-PERSEI IN QUIESCENCE AND OUTBURST

We report Ginga observations of the old nova GK Persei in quiescence, as well as a brief scanning observation during an outburst. The X-ray spectrum in quiescence is well fitted by thermal bremsstrahlung emission of very high temperature (kT approximately 30 keV), plus an iron emission line. In contrast, the outburst spectrum is complex and comprises two continua with different column densities (N(H) approximately 10(23) and approximately 10(24) cm-2). The 351-s spin modulation of GK Per was clearly detected in the quiescence observation, which confirms the results of previous EXOSAT observations. The folded light curve shows two peaks that are not separated by 180-degrees in phase, which is indeed quite different from the EXOSAT outburst data. It is, however, similar to the EXOSAT observation at a similar flux level.