A photographic survey of the sky south of declination −17°, produced jointly by the European Southern Observatory’s 1-m Schmidt camera and the 1.2-m United Kingdom Schmidt Telescope at Siding Spring. Both telescopes have the same focal length as the 1.2-m Oschin Schmidt, which produced the northern-hemisphere Palomar Observatory Sky Survey, so the scale of the plates in each survey is identical. The Southern Sky Survey consists of 606 pairs of red-sensitive and blue-sensitive plates; the red plates were taken in 1978–90 with the ESO Schmidt and the blue plates 1974–87 with the UK Schmidt.