A ROSAT medium-sensitivity Galactic plane survey at 1808, l, 2808

We have performed a moderately deep soft X-ray ð0:1–2 keVÞ survey of the Galactic plane using pointed observations with the ROSAT Position Sensitive Proportional Counter (PSPC). The survey is more than an order of magnitude more sensitive than previous X-ray surveys near the Galactic plane. The data consist of nine fields each of <10 ks exposure, pointed at positions on or very close to the Galactic plane ðjbj, 08:3Þ in the longitude range 1808 & l & 2808. This region has relatively low X-ray absorbing material out to distances of several hundred pc and presents fewer source-confusion problems than at other longitudes. The total sky area surveyed was 2.5 deg2; this yielded 93 sources, 89 of which were detected in the ‘hard ’ ð0:4–2:0 keVÞ band. Nine sources were detected in both ‘soft ’ ð0:1–0:4 keVÞ and hard bands. In the hard band, the survey coverage is *90 per cent for sources brighter than 0.002 count s21 ð, 2 10214 erg cm22 s21Þ, but falls steeply below this value, with the weakest sources being, 0.001 count s21. The median limiting flux is <0.0013 count s21 ð, 1:3 10214 erg cm22 s21Þ. There are 64 sources with hard-band count rates. 0.002 count s21. We present the catalogue of X-ray sources and the number– flux relations ðlogN–log SÞ. Eighteen sources have possible identifications from the SIMBA