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M 33 Chandra X-Ray Point Source Catalog

Published by High Energy Astrophysics Science Archive Research Center | National Aeronautics and Space Administration | Metadata Last Checked: September 14, 2025 | Last Modified: 2025-09-10
This database table contains a source list for three Chandra observations of the Local Group galaxy M 33. The observations were centered on the nucleus and on the star-forming region NGC 604. A total of 261 sources were detected in an area of about 0.2 square degrees down to a flux limit of 3 x 10<sup>-16</sup> erg/s/cm<sup>2</sup>, which corresponds to a luminosity of ~2 x 10<sup>34</sup> erg/s at a distance of 840 kpc. The luminosity functions of the X-ray sources observed in M 33 have been constructed and are consistent with those of other star-forming galaxies, taking into account background contamination. In addition, the combination of X-ray color analysis and the existence of "blue" optical counterparts strongly indicates that the X-ray point source population in M 33 consists of young objects. Above 3 x 10<sup>35</sup> erg/s, there are few X-ray sources in the locus of the X-ray hardness ratio diagram that is generally populated by low-mass X-ray binaries. Notice that each of the 261 X-ray sources in the source list has 3 entries in this table, one for each separate Chandra observation, making a total of 783 entries. The Chandra datasets from which this source list was compiled are available by <a href="/db-perl/W3Browse/w3query.pl?tablehead=name%3Dheasarc_chanmaster&sortvar=obsid&bparam_obsid=786%3B+1730%3B+2023">querying CHANMASTER for obsids 786, 1730, and 2023</a>. This table was created by the HEASARC in December 2005 based on the machine-readable version of Table 3 in the above-mentioned Grimm et al. (2005) reference obtained from the ApJ Electronic Edition website. This is a service provided by NASA HEASARC .

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