Southern Infra-Red Standards and the Absolute Calibration of Infra-Red Photometry

Infrared photometric measurements of a set of bright southern stars are presented. Flux comparisons are made relative to gamma Crucis between 1.25 mu and 11.2 mu , and recent solar data are used to establish the actual flux values, using alpha CenA as a transfer star. A model of a single star ( alpha Lyr) is used to establish an absolute calibration, and solar colors, transferred via alpha CenA (with the assumption that the red and infrared spectral energy distribution of alpha CenA is identical to that of the Sun) provide a new magnitude scale. The 4.8- mu 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. (auth)