THE ROSAT GALACTIC PLANE SURVEY - ANALYSIS OF A LOW-LATITUDE SAMPLE AREA IN CYGNUS - THE OBSERVATIONS

The analysis of the part of the ROSAT all-sky survey covering the gala ctic plane is the scope of a dedicated project called the ROSAT Galact ic Plane Survey. In order to statistically understand the nature of th e approximate to 14 000 sources discovered by ROSAT at \b\ less than o r equal to 20 degrees, a number of sample areas have been chosen for f ollow-up optical identification. In this paper we present the X-ray an d optical material gathered in a region located in the Cygnus constell ation, centered at l = 90 degrees, b = 0 degrees and covering an area of 64.5 deg(2). A total of 95 and 128 sources are detected with a maxi mum likelihood larger than 10 and 8 respectively. With a typical surve y exposure time of the order of 700 to 900 s the flux completeness lev el is approximate to 0.02 cts s(-1) corresponding to approximate to 2 10(-13) erg cm(-2) s(-1). The position of the sample area allows to in vestigate the soft X-ray content of a rather typical region of the gal actic plane. In this paper we describe the details of the observationa l procedures and data reduction. For each ROSAT source are list the ma in X-ray characteristics together with those of the proposed optical i dentification. When appropriate, we also show optical spectra and find ing charts. The full analysis and discussion of these data are present ed in a companion paper (Motch et al. 1997).(1)