Radio positions and optical identifications for a complete sample of southern flat-spectrum radio sources - I. Region 06h to 18h.

Optical identifications have been sought for 73 southern radio sources using new positions determined with the six-dish array of the Fleurs synthesis telescope. These sources constitute a complete sample drawn from the Parkes 2700-MHz catalog. They are all flat-spectrum (alpha of greater than 0.5) sources stronger than 0.25 Jy at 2700 MHz and lie between R.A. (B1950.0) 06h00m and 18h00m and Dec. (B1950.00) -80 deg, and -50 deg. Sources with b of between -5 and 5 deg are not included. The new radio positions have standard deviations of about 2 arcsec in right ascension and declination. The optical positions are with respect to the FK4 reference system as defined by the Perth catalogs and have position uncertainties of about 0.5 arcsec. Magnitude estimates are on the J scale and are accurate to about 0.4 mag for stellar-like objects and 0.5 to 1.0 mag for galaxies. The sample is complete to the 22.5-mag limit of the SERC J sky atlas. The probable identifications consist of 43 stellar-like objects, 21 galaxies and 10 empty fields.