All the optical material was collected at the Observatoire de Haute-Provence, CNRS, France. Observations took place during several runs spanning from 1991 May till 1993 September. This observing programme was part of a general project aiming at the optical identification and follow-up observations of area and X-ray selected sources extracted from the RGPS. All spectral and photometric data reductions were performed using standard MIDAS procedures (Banse et al. 1983).
Spectroscopic observations were obtained with the CARELEC spectrograph
(Lemaitre et al. 1990) attached at the 1.9m telescope. Several
CCDs have been used during the course of the observations (see Table
1 (click here)). Low resolution spectroscopy (
; FWHM resolution 
14 Å) and medium resolution blue spectroscopy
(
; FWHM resolution 
1.8 Å) were
acquired using a 260 Å/mm grating and 33 Å/mm grating, respectively.
Two-dimensional spectra were corrected for bias and flat-field. Extracted spectra
were calibrated in wavelength using arcs of iron and helium lamps. Observations of
standard stars allowed to formally calibrate in flux all spectra. However, bad
meteorological conditions and the narrow slit entrance width used for some bright
stars may considerably bias the mean flux level on occasions and therefore, the
flux information should be considered with some caution.
CCD images were collected using the standard camera at the 1.2m telescope. Most of
the time the Johnson B, V, and I filters were used. Depending on the CCD
mounted, the field of view was either 7.1
4.4
(RCA) or
6.5
6.5
(TK512). All CCD frames were corrected for bias
and flat-field. These CCD images were mainly used as a guide for selecting potentially
interesting candidates for spectroscopic observations and to provide
differential astrometry and photometry with respect to Guide Star Catalogue entries
(GSC; Lasker et al. 1990).