We report on the first results from a redshift survey of a flux-limited sample of X-ray clusters selected serendipitously from the ROSAT PSPC data archive. We spectroscopically confirm 15 clusters in the range 0.3 < z < 0.7, to a flux limit of ≃ 3.9 × 10 −14 erg s −1 cm −2 , over a survey area of 17.2 deg 2. The surface density of clusters in our survey is 2.0 +0.4 −0.3 deg −2 , in good agreeme...

We present the analysis of pointed ROSAT PSPC observations of five of the most luminous, intermediate redshift (0:1 < z < 0:15) clusters of galaxies detected in the ROSAT All-Sky Survey. The PSPC data are combined with optical CCD images and spectra to examine the relationship between clusters and their central cluster galaxies (CCGs). Abell 1068, Abell 1361 and Abell 1664 contain three of the ...

We present the results of a systematic search for old isolated neutron stars (ONSs) in the direction of two giant molecular clouds in Cygnus (Rift and OB7). From theoretical calculations, we expect the detection of a large number of ONSs with the PSPC on board ROSAT. By analyzing the PSPC pointings in the direction of the clouds, we find four sources characterized by count rates (∼ 10 c s) and ...

We have made a series of joint spectral fits for two blank fields, the Lockman Hole and the Lynx-3A field, where a significant amount of both ASCA and ROSAT PSPC data exist after thorough screenings. The ASCA SIS, GIS and ROSAT PSPC spectra from these fields have been fitted simultaneously. Comparison at E > 1 keV shows general agreement within 10% in the Lockman Hole data and a 20−30% disagree...

Nova LMC 1995 was detected with ROSAT as an X-ray source in repeated observations between 1995 and 1998, starting five months after the outburst. In February 1998, 3 years after the nova outburst, ROSAT PSPC data show that this is the only LMC post-nova – and one out of three among '100 altogether – that appeared as a bright supersoft X-ray source after the outburst. The PSPC data are satisfact...

We carefully reanalyze the ROSAT PSPC X-ray spectro-photometric observations of HCG 16 (Arp 318) and compare them to optical and radio data. We detect diffuse emission in six regions filling half of the 8 radius circle around the optical center of the group: one region encompassing galaxies a & b, two regions surrounding the group galaxies c & d, one associated with a background radio-source, o...