Identification of radio sources in the south polar cap.

Optical search areas centered on the radio positions of 108 radio sources from the Parkes 2700-MHz survey (fourth part) have been examined for optical counterparts by using two-color plates and the ESO quick-blue-survey film copies. Twenty-one new identifications are proposed, of which 12 are QSO candidates and 9 are galaxies, while the search areas of five radio sources appear blank to the limit of the ESO film copies. Ten of the QSO candidates were selected for their ultraviolet excess and the remaining two purely on the basis of positional agreement. With this work the program of optical identification in the region south of declination -75 deg has been completed so as to provide a sufficient number of potential position calibrators well-distributed in right ascension. Finally, this program has also shown that no substantial obscuration can be attributed with certainty to this whole area of the sky.