ROSAT HRI observations of the globular clusters M13 and M92

We report on 40 ks of ROSAT High Resolution Imager (HRI) observations of the globular cluster M92 (NGC 6341) and 20 ks of observations of the globular cluster M13 (NGC 6205). We find that the low-luminosity (10(325) erg s(-1) at 7.5 kpc) source previously observed near the core of M92 with the ROSAT Position Sensitive Proportional Counter (PSPC) remains unresolved at HRI resolution; we can identify it with M92 with 99 per cent confidence. In M13 we find that the source seen with the ROSAT PSPC lies within the core and is possibly associated with the cluster (96 per cent confidence). We find probabilities of 99.8 per cent (M92) and 98 per cent (M13) for the presence of additional unresolved emission within these globular clusters. We interpret these results in light of current theories regarding the low-luminosity sources.