XRAY_4U (E0): Fourth UHURU X-ray Catalog, 1979
FILE: xray_4u.e0(339 entries)
CONTENTS: Fourth UHURU X-ray Catalog, 1979
DATASET: This file comes in HyperSky dataset E-2, version 19930622. Availability on HyperSky CD-ROM: Vol. 1 (1993)
DESCRIPTION: This datafile contains a total of 339 entries from the Fourth UHURU X-ray Catalog, based on observations by the UHURU X-ray satellite, by W. Forman et al, initially published in 1977 in Center for Astrophysics Preprint #763. The HyperSky catalog file is based on the machine-readable version of the catalog, as provided on the NASA/GSFC Astronomical Data Center (ADC) cd-rom "Selected Astronomical Catalogs", Volume 1.
Of most interest to general users are the catalog cross-identifications with various astronomical objects, including stars, galaxies, and the like.
DATA: The HyperSky datafile contains the following data from the catalog:
POSITION: Right Ascension and Declination are based on the 1950 catalog values, precessed to equinox 2000.
MAG: No magnitudes are provided by the catalog.
TY: All objects have type "Ex", indicating a Xray emission source.
IDENTIFICATION: The Fourth UHURU catalog designation, having the general form 4Uhhmm+dd, where hhmm is the approximate 1950 RA, and +dd is the approximate 1950 declination.
COMMENTS: The comment lines contain the following information, provided if available for each radio source identification:
* Intensity. The X-ray intensity is indicated by the string "i=" followed by a number (eg, i=2.18). According to the catalog, this intensity is "in units of [the] given detector". No further detail is offered, nor are detector descriptions provided in the machine-readable catalog version. Hence the values should be considered useful only in a roughly relative sense. For example, i=3.45 is probably indicates a stronger source than i=1.23.
* Comments. Up to 40 characters of non-structured comments are provided for each catalog entry. These comments are primarily cross-identifications with objects and/or sources from other catalogs. The following abbreviations appear frequently, and indicate entries in the corresponding catalogs:
A : Ariel Catalog of X-Ray Sources
2A : Second Ariel X-Ray Catalog
3C : Third Cambridge Radio Catalog
3U : Third UHURU X-Ray Catalog
ABELL : Abell Catalog of Galaxy Clusters
MKN: Markarian Catalog of Active Galaxies
Other abbreviations will also appear less frequently.