PKSCAT90 is the Parkes Catalog (1990) and consists of radio and optical data for 8,264 radio sources. It covers essentially all the sky south of declination +27 degrees but largely excludes the Galactic Plane and the Magellanic Cloud regions. The latter zones have been the subject of other, specialist surveys. A few data errors in Version 1.00 have been corrected in the present edition (see below). This version of the Parkes Radio Source Catalog is entitled "PKSCAT90 Version 1.01." The original Parkes radio catalog was compiled from major radio surveys with the Parkes radiotelescope at frequencies of 408 MHz and 2700 MHz. This work spanned a period of nearly 20 years and was undertaken largely by John Bolton and his colleagues. Since then, improved positions, optical identifications, and redshifts have been obtained for many of the sources in the catalog. Furthermore, flux densities at several frequencies have supplemented the original surveys so that the measurements now cover the frequency range 80-22,000 MHz. However, coverage at the highest frequencies is still sparse. Important contributions to the usefulness of the catalog have been radio data from the Molonglo 408-MHz survey and the 80-MHz Culgoora measurements of Slee et al. PKSCAT90 should thus be regarded as a compendium of radio and optical data about southern radio sources. However, at the moment, it contains only sources originally found in the Parkes 2700-MHz survey (see e.g. Part 14, Bolton et al, 1979, Aust J Phys, Astrophys Suppl, No. 46 and references therein.) The original radio survey data of the catalog and the optical identifications have been published in a series of papers in the Australian Journal of Physics (see above reference). The associated optical spectral data on which redshifts were obtained has also been published, mainly in Astrophysical Journal and Monthly Notices of the Royal Astronomical Society. About the completeness levels of the catalog in various parts of the sky: users should note that the sky zone between -4 and +4 degrees has been the subject of a re-survey and is now complete to 0.25 Jy. The author Alan Wright notes that "PKSCAT90 was produced at a time when relational databases were in their infancy. In the future we anticipate making the individual data sources available separately -- through such search systems as SIMBAD -- rather than in an 'omnibus' catalog like PKSCAT90. For both the Northern and Southern hemispheres, superior and deeper finding surveys now exist: the 87GB catalog in the North (Gregory and Condon et al. 1991, ApJ, 75, 1011, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VIII/14">CDS Catalog VIII/14</a>) and the PMN catalogs (Griffith and Wright 1993, AJ, 105, 1666, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VIII/38">CDS Catalog VIII/38</a>, available at the HEASARC as the PMN table) in the South." This table was updated by the HEASARC in July 2015 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VIII/15">CDS Catalog VIII/15</a> file pkscat90.dat, replacing a version based on the original (version 1) PKSCAT90, which was created in 1995. It was further updated in September 2015 as noted in the "Version 1.01 Modifications" section above. This is a service provided by NASA HEASARC .
