A summary of spectroscopic identifications is presented for a complete sample of bright, soft, high galactic-latitude X-ray sources drawn from the ROSAT All-Sky Survey (RASS) which have PSPC count-rates CR>0.5cts/s, hardness ratios HR1<0, and galactic latitudes |b| > 20 degrees. Out of a total of 397 sources, 270 had previously catalogued counterparts, although most of these were not previously known as X-ray sources; of the remaining 127 sources neither X-ray nor optical properties were previously known. Of the whole sample of very soft X-ray sources 155 were also discovered by the Wide-Field-Camera on board ROSAT. Spectroscopic identifications are presented for 108 sources and other identifications for a further 18 sources; 1 source remains unidentified so far. In practically all cases a unique optical counterpart exists, facilitating identification. The largest source classes are AGN, magnetic cataclysmic variables, and hot white dwarfs This database was created by the HEASARC in April 1999 based on tables provided by the authors to CDS/ADC. This is a service provided by NASA HEASARC .

This table contains a catalog of 3405 X-ray sources from the ROSAT All Sky Survey (RASS) Bright Source Catalog which fall within the area covered by the 6dF Galaxy Survey (6dFGS). The catalog is count-rate limited at 0.05 ct s^-1 in the X-ray and covers the area of sky with Declination < 0 degrees and |b| > 10 degrees. The RASS-6dFGS sample was one of the additional target catalogs of the 6dFGS and as a result the authors obtained optical spectra for 2224 (65 per cent) RASS sources. Of these, 1715 (77%) have reliable redshifts with a median redshift of z = 0.16 (excluding the Galactic sources). For the optically bright sources (b_J <= 17.5) in the observed sample, over 90% have reliable redshifts. The catalog mainly comprises quasi-stellar objects (QSOs) and active galaxies but also includes 238 Galactic sources. Of the sources with reliable redshifts, the majority are type 1 active galactic nuclei (AGN, 69%), while 12% are type 2 AGN, 6% absorption-line galaxies and 13% are stars. The authors also identify a small number of optically faint, very low redshift, compact objects which fall outside the general trend in the b_J - z plane. The RASS-6dFGS catalog complements a number of Northern hemisphere samples, particularly the ROSAT Bright Source Catalogue-NRAO VLA Sky Survey (RBSC-NVSS) sample (Bauer et al. 2000, ApJS, 129, 547), and furthermore, in the same region of sky (-40 degrees < Declination < 0 degrees) reveals an additional 561 sources that were not identified as part of that sample. The authors detect 918 sources (27%) of the RASS-6dFGS sample in the radio using either the 1.4 GHz NVSS or the 843 MHz Sydney University Molonglo Sky Survey (SUMSS) catalogues and find that the detection rate changes with redshift. At redshifts larger than 1 virtually all of these sources have radio counterparts and with a median flux density of 1.15 Jy, they are much stronger than the median flux density of 28.6 mJy for the full sample. The authors attribute this to the fact that the X-ray flux of these objects is being boosted by a jet component, possibly Doppler boosted, that is only present in radio-loud AGN. The RASS-6dFGS sample provides a large set of homogeneous optical spectra ideal for future studies of X-ray emitting AGN. This table was created by the HEASARC in April 2010 based on an electronic version of Table 3 from the reference paper obtained from the MNRAS web site. This is a service provided by NASA HEASARC .

The ROSAT Bright Survey (RBS) is an identification program of the more than 2000 X-ray sources at high galactic latitude (absolute latitude b > 30 degrees) with a count rate of more than 0.2 ct/s detected during the ROSAT All-Sky Survey (Voges et al. 1999, A&A, 349, 389). The RBS identification program is more than 99.5% complete. A sub-sample of 931 sources with a count rate of more than 0.2 ct/s in the hard spectral band from 0.5 to 2.0 keV is 100% identified. The total survey area comprises 20391 square degrees at a flux limit of 2.4 x 10^-12 erg/s/cm² in the 0.5 to 2.0 keV band. About 1500 sources of the complete sample were identified by correlating the RBS with the SIMBAD and NED databases. The remaining ~500 sources were identified by low-resolution optical spectroscopy and CCD imaging utilizing various telescopes. The RBS Catalog contains optical and X-ray information for each source, including the most massive complete sample of X-ray selected AGN ever assembled, with a total of 669 members, and a well-populated X-ray selected sample of 302 clusters of galaxies with redshifts of up to 0.52. Three X-ray sources in the RBS remain without optical counterparts, RBS 378, RBS 1223, and RBS 1556. While the first is a possible X-ray transient, the latter two sources are isolated neutron star candidates (Motch et al. 1999, A&A, 351, 177; Schwope et al. 1999, 341, L51). As noted elsewhere, this electronic version of the RBS Catalog has a small number of additions/corrections compared to the published version. This database was created by the HEASARC in August 2000 based on a machine-readable table supplied to the HEASARC by Axel Schwope in April 2000. Note that this table is an expanded version of Table 2 in the published paper and contains the following additional parameters: HR2 (hardness_ratio_2), and the Galactic hydrogen column density (nh_21cm). This is a service provided by NASA HEASARC .