092204

The thermal evolution of old neutron stars (NSs) which depends on fundamentalproperties of matter is still not well understood because of scarcity ofobservations. To study cooling and heating of old NSs HST observations in theUV range have been initiated. To reliably separate the thermal UV radiationfrom the magnetospheric radiation the X-ray emission from the pulsar must beconstrained but only 18 of the 28 pulsars of the HST program have been observedwith reasonably deep X-ray exposures. Therefore we propose exploratory X-rayobservations of the remaining 10 pulsars. Combined with optical-UV data theresults of these observations will strongly advance our understanding of the NSevolution. [truncated! Please see actual data for full text]