The original version of the INTEGRAL Reference Catalog as published in 2003 classified previously known bright X-ray and gamma-ray sources before the launch of INTEGRAL. These sources are, or have been at least once, brighter than ~1 milliCrab above 3 keV energy, and are expected to be detected by INTEGRAL. This catalog was used in the INTEGRAL Quick Look Analysis (QLA) to discover new sources or significantly variable sources. The authors compiled several published X-ray and gamma-ray catalogs, and surveyed recent publications for new sources. Consequently, there were 1121 sources in the original INTEGRAL Reference Catalog. In addition to the source positions, an approximate spectral model and expected flux were given for each source, and the expected INTEGRAL counting rates based on these parameters was derived. Assuming the default instrument performances and at least ~10<sup>5</sup> seconds exposure time for any part of the sky, it is expected that INTEGRAL will detect at least ~700 sources below 10 keV and ~400 sources above 20 keV over the mission life. After the launch of INTEGRAL, a version of this catalog was placed on the ISDC website at <a href="http://www.isdc.unige.ch/integral/science/catalogue">http://www.isdc.unige.ch/integral/science/catalogue</a> and has been updated periodically since then by adding, for example, new sources discovered by INTEGRAL itself (indicated by the IGR prefix in the name). This HEASARC table is based on the web version at the ISDC, and will be updated within a few days of whenever the latter is updated. This database table is updated automatically in the HEASARC database system within one week of any changes to the online web page maintained by the INTEGRAL Science Data Center at the URL <a href="http://www.isdc.unige.ch/integral/catalog/latest/catalog.html">http://www.isdc.unige.ch/integral/catalog/latest/catalog.html</a> This is a service provided by NASA HEASARC .
