Locations of the 158 Northern+Equatorial fields (Smith et al. 2002; Smith, Tucker, Allam, et al., in prep) (asterisks) and the 58 fields of the southern extension to the primary standard star network (unfilled squares). Circled symbols indicate u'g'r'i'z' standard stars or fields for which there is current or upcoming Landolt UBVRcIc photometry (Landolt 1973, 1983, 1992) or for which Landolt is currently obtaining UBVRcIc photometry (Landolt, in prep).
The Southern u'g'r'i'z' standards were developed as an extension of the original set of Northern+Equatorial standards in order to serve southern hemisphere observations, including those by the Dark Energy Survey (DES); for more information on the DES, please see the Dark Energy Survey Homepage.