Why do we need southern hemisphere standard stars if the SDSS is a northern hemisphere survey?
… The filter set for the SDSS has many astrophysical benefits when compared to other wide-band filter systems. Though the SDSS proper is a northern hemisphere survey, there are several other groups and individual investigators who will observe objects in the southern hemisphere using these same filters and they need standard stars to compare their observations to and use these observations to compare to the northern hemisphere data. … Our group has under taken this effort, using essentially the same people, reduction software and selection and observing techinques that were used in the setup of the initial u’g’r’i’z’ standard stars in use in the northern hemisphere. In this way, we hope to maintain a consistent approach to entire standard network.