Southern infra-red standards and the absolute calibration of infra-red photometry.

Infra-red photometric measurements of a set of bright southern stars are presented. Flux comparisons are made relative to Crucis between i.z5 and I I [t, and recent solar data is used to establish the actual flux values, using cc CenA as a transfer star. A model of a single star (cc Lyr) is used to establish an absolute calibration, and solar colours, transferred via cc CenA, (with the assumption that the red and infra-red spectral energy distribution of cc CenA is identical to that of the Sun) provide a new magnitude scale. The - flux in late K and M stars appears to be significantly depressed. A major contributor to this depression is probably absorption by the fundamental vibration rotation bands of CO.