A Double Colour Index Diagram for the 273 Brightest Infrared Sources in the CRL Catalogues

A double colour index diagram for 273 bright. infrared sources with the photometric data in the 4μ, llμ and 20μ wave-bands listed in the CRL catalogue is presented in this paper. It is obviously shown in the diagram that the positions of the maser sources, the H Ⅱ regions and the galaxies appear in groups respectively.The characteristics of the sources are analysed according to the positions of the sources with respect the blackbody curve in the diagram.