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|The ROSAT North Ecliptic Pole Survey: the Optical Identifications|
The X-ray data around the North Ecliptic Pole (NEP) of the ROSAT All SkySurvey have been used to construct a contiguous area survey consistingof a sample of 445 individual X-ray sources above a flux of~2×10-14 ergs cm-2 s-1 in the0.5-2.0 keV energy band. The NEP survey is centered atα2000=18h00m,δ2000=+66deg33' and covers aregion of 80.7 deg2 at a moderate Galactic latitude ofb=29.8d. Hence, the NEP survey is as deep and covers a comparable solidangle to the ROSAT serendipitous surveys but is also contiguous. We haveidentified 99.6% of the sources and determined redshifts for theextragalactic objects. In this paper we present the opticalidentifications of the NEP catalog of X-ray sources including basicX-ray data and properties of the sources. We also describe with somedetail the optical identification procedure. The classification of theoptical counterparts to the NEP sources is very similar to that ofprevious surveys, in particular the Einstein Extended Medium SensitivitySurvey (EMSS). The main constituents of the catalog are active galacticnuclei (AGNs) (~49%), either type 1 or type 2 according to the broadnessof their permitted emission lines. Stellar counterparts are the secondmost common identification class (~34%). Clusters and groups of galaxiescomprise 14%, and BL Lacertae objects 2%. One non-AGN galaxy and oneplanetary nebula have also been found. The NEP catalog of X-ray sourcesis a homogeneous sample of astronomical objects featuring completeoptical identification.
|Arcsecond Positions of UGC Galaxies|
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
|Groups of Galaxies in the ROSAT North Ecliptic Pole Survey|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...449..422H&db_key=AST
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