Abstract

We have made a complete survey of the CS(2 -1) emission toward IRAS point sources in the galactic plane. The sources observed were selected according to their far infrared (FIR) colors, which are characteristic of UC H II regions. They have 25 ?m/12 ?m flux ratios larger than 3.7 and 60 ?m/12 ?m flux ratios larger than 19.3. The survey covered a region from b = -2° to 6 = 2° from l -300° to l -0° and from l = 0° to l = 60°, and from b 4° to b -4° elsewhere. We detected 843 sources out of 1427 sources observed. The distributions of detected and undetected sources in a FIR color-color diagram show some differences, suggesting that more than one type of object is present in our observed sample.