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Description
The Midcourse Space Experiment (MSX) Ultraviolet Point Source Catalog contains 47,283 point sources (the HEASARC notes that there actually 47,318 sources in this version of the table, 35 more than this number) from a set of 201 observations that surveyed approximately half the sky and from a set of 32 pointed observations toward specific targets. For each source, the catalog provides the position, UV magnitude and uncertainty in at least one of six filters, and, where possible, an identification of a nearby source from the SIMBAD database. If a nearby source is identified, its proximity to the MSX source, and if known, the spectral type and the B and V magnitudes of the SIMBAD object are also provided. There were 11,565 matches between MSX and SIMBAD objects (the HEASARC notes that there actually 11,662 matches in this version of the table, 97 more than this number), and the authors estimate the number of false identifications to be about 3%. The limiting fluxes differ from filter to filter, and range from 10<sup>-16</sup> erg/s/cm<sup>2</sup>/Angstrom for IUN4 to 7.8 x 10<sup>-12</sup> erg/s/cm<sup>2</sup>/Angstrom for IUW3. Because of variations among the observation sets, the catalog is not complete to the limiting magnitudes for the filters. The UV instrument on MSX was named UVISI (Mill et al., 1994, Journal of Spacecraft and Rockets, 31, 900 (1994JSpRo..31..900M in ADS); Carbary et al., 1994, Applied Optics, 33, 4201 (1994ApOpt..33.4201C in ADS)). The fields-of-view for the narrow-field and wide-field UV imagers were 1.46 x 1.19 degrees (detector pixels of 20.6" x 17.5") and 13.4 x 9.2 degrees (detector pixels of 3.12' x 2.27'), respectively. Four filters were used with the narrow-field imager (IUN) with effective wavelengths centered at 2480 Angstrom (IUN3), 2310 Angstrom (IUN4), 2230 Angstrom (IUN5), and 2930 Angstrom (IUN6). Two filters were used with the wide-field imager (IUW) and centered at 1320 Angstrom (IUW3) and 1560 Angstrom (IUW6). The HEASARC has removed from this table the parameter describing the objects' magnitude in the IUN5 filter as all of the sources had null values for this parameter. The CDS had previously made the following modifications compared to the version of the catalog as published in the reference paper: <pre> (1) The angular distances to the SIMBAD object (column "AngDist" of file catal.dat, called 'Offset' in this HEASARC table) was recomputed at CDS, the original values looking suspect. (2) In the course of this modification, 17 SIMBAD IDs were removed due to a large offset, most likely due to a sign error in the interpretation of SIMBAD's declination for IDs: 003341+001712 063054+004539 063211+005630 063754+003151 133358+001928 142557+003939 144541+002439 155701+004808 162743+004620 185855+003355 191033+004132 193004+005316 194525+001239 195040+004101 195717+001959 202844+005149 234324+000729 </pre> This table was created by the HEASARC in April 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/II/269">CDS Catalog II/269</a> file catal.dat. This is a service provided by NASA HEASARC .
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