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EUV - EUV Master Catalog


The EUV database table is the Extreme Ultraviolet (EUV) Master Catalog and contains a compendium of EUV sources. It is comprised of selected fields from the following HEASARC EUV database tables:

 * EUVEBSL - First Extreme UltraViolet Explorer Bright Source List

 * EUVECAT2 - Second Extreme UltraViolet Explorer Source Catalog

 * ROSWFC2RE - ROSAT Wide Field Camera 2RE Catalogue

 * ROSATXUV - ROSAT Wide Field Camera Pointed Phase Catalog of XUV Sources

 * EUVERAP2 - Second Extreme UltraViolet Explorer Right Angle Program Catalog

 * EUVEXRTCAT - All-Sky Catalog of Faint EUV Sources

Notice that we have not included EUVECAT1 (First Extreme UltraViolet Explorer Source Catalog) and WFCBSC (ROSAT Wide Field Camera Bright Source Catalog), as these are obsolete catalogs superceded by EUVECAT2 and ROSWFC2RE, respectively.

The EUVEBSL database table contains a detailed list of verified bright EUVE sources detected during the survey phase of the EUVE mission (calibration targets are also included). Two distinct surveys, the all-sky and deep surveys, were conducted by the four EUVE telescopes during the first six months of the mission. EUVEBSL contains 356 sources.

EUVECAT2 is the 2nd Catalog of EUV objects detected by the Extreme Ultraviolet Explorer (EUVE) and published by Bowyer et al. in 1996 (ApJS, 102, 129). The data include (i) all-sky survey detections from the initial 6-months scanner survey phase, (ii) additional scanner detections made later during specially programmed observations designed to fill in low-exposure sky areas of the initial survey, (iii) sources detected with deep-survey telescope observations along the ecliptic plane, (iv) objects detected by the scanner telescopes during targeted spectroscopy observations, and (v) other observations. Plausible optical, X-ray, radio, and/or UV identifications are available for about 65% of the EUV sources. EUVECAT2 contains 801 sources.

ROSWFC2RE is the ROSAT Wide Field Camera 2RE Source Catalogue. It contains 479 EUV sources found during the ROSAT all-sky survey of July 1990 to January 1991. The information in this database is based on what has been published by Pye et al. (1995, MNRAS, 274, 1165). It supersedes the earlier WFC Bright Source Catalog (WFCBSC), but we have retained the latter in the EUV database for reasons of completeness

The ROSATXUV database table is a catalog of XUV sources (Kreysing H.C., Brunner H., and Staubert, R. 1995, A&AS, 114, 465), extracted from observations by the ROSAT Wide Field Camera during the pointed phase. The 5916 WFC pointed observations that were included are from the calibration and verification phase in June 1990 and from the period of pointed observations from February 9, 1991 to July 15, 1994. The catalog contains 1022 independent source detections corresponding to 4 different filters (S1, S2, P1 and P2) and 328 individual sources, many of which were observed repeatedly. Only ROSATXUV detections in the S1 filter band are included in the EUV table. If there are multiple observations of a single source/position in ROSATXUV, then only one entry for that source will be present in the EUV Master Catalog.

The EUVERAP2 database table is a catalogue of 235 extreme ultraviolet (EUV) sources, of which 169 are new detections, using the EUVE Observatory's Right Angle Program (RAP) data obtained with the A, B and C scanners and the Deep Survey (DS) instrument in the period from January 1994 through November 1998. The EUVE RAP used the all-sky survey telescopes (also known as the "scanners"), which were mounted at right angles to the Deep Survey and Spectrometer (DS/S) instruments, in order to obtain photometric data in four wavelength bands centered at 100 Angstroms (Lexan/B), 200 A (Al/Ti/C), 400 A (Ti/Sb/Al or Dagwood), and 550 A (Sn/SiO). The EUVERAP2 catalogue covers 17% of the sky and includes observations that were made subsequent to the publication of the first EUVE RAP catalog (EUVERAP1, which listed RAP data that had been obtained up until 1994 January); the data from EUVERAP1, together with additional RAP data obtained through 1994 December, are contained in the EUVECAT2 database table (The Second EUVE All-Sky Catalog of Bowyer et al. 1996, ApJS, 102, 129). Thus, RAP sources detected in 1994 will be contained in both EUVECAT2 and EUVERAP2, albeit different selection criteria were used in the two catalogs.

The EUVEXRTCAT database table is a catalog of 534 objects detected jointly in the Extreme Ultraviolet Explorer (EUVE) (100 Angstrom (AA) band) All-Sky Survey and in the ROSAT X-ray Telescope (XRT) (0.25 keV band) All-Sky Survey. The joint selection criterion within a 1.5 arcminute positional tolerance permitted the use of a low count rate threshold in each survey. This low threshold was roughly 60% of the threshold used in the previous EUVE all-sky surveys, and 166 of the objects listed in this table were new EUV sources, appearing neither in the Second EUVE Source Catalog nor in the ROSAT Wide Field Camera Second Catalog. Preliminary identifications are offered for 105 of the 166 sources not previously reported in any EUV catalog: by far the most numerous (81) of the identifications are late-type (F-M) stars, while 18 are other stellar types, only 5 are white dwarfs, and none are extragalactic. The paucity of WDs and extragalactic objects may be explained by a strong horizon effect wherein interstellar absorption strongly limits the effective new-source search volume, and, thereby, selectively favors low-luminosity nearby sources over more luminous but distant objects. Notice that, with the adopted 1.5 arcminute acceptance criterion, about 50 spurious detections are expected.


This database is periodically updated by the HEASARC whenever one of the component database tables is modified or a new component database table is added.


The name of the object in the originating EUV Catalog.

An alternate name for the object as quoted in the originating EUV Catalog, usually the name of the proposed optical counterpart, but sometimes an alternate EUV identifier.

The name of originating database table for the source.

The Right Ascension of the object.

The Declination of the object.

The Galactic Longitude of the object.

The Galactic Latitude of the object.

The EUV count rate, in counts per second. For entries from the tables using data from ROSAT WFC observations (ROSWFC2RE and ROSATXUV), this is the count rate in the S1 band (60-140 Angstroms, or 90-206 eV), while for entries from the EUVE tables (EUVEBSL, EUVECAT2, and EUVERAP2), this is the count rate in the Lexan/B band (50-180 Angstroms, or 70-250 eV).

The error in the EUV count rate, in counts per second.

The spectral type for EUV sources identified with stars, or, for some catalogs, the source type, e.g., 'Seyfert', for non-stellar identifications.

The apparent magnitude of the proposed optical counterpart (usually the V-band magnitude, but in the case of some entries from the ROSWFC2RE or the EUVERAP2 Catalogues, it may be the apparent magnitude in another band, e.g., B).

The Browse object classification from the originating catalog (based on the spect_type parameter).

Contact Person

Questions regarding the EUV database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk