A CS(2-1) SURVEY OF IRAS POINT SOURCES WITH COLOR CHARACTERISTICS OF ULTRA-COMPACT H-II REGIONS

We have made a complete survey of the CS(2 - 1) emission toward IRAS p oint sources in the galactic plane. The sources observed were selected according to their far infrared (FIR) colors, which are characteristi c of UC H II regions. They have 25 mu m/12 mu m flux ratios larger tha n 3.7 and 60 mu m/12 mu m flux ratios larger than 19.3. The survey cov ered a region from b = -2 degrees to b = 2 degrees from l = 300 degree s to l = 0 degrees and from l = 0 degrees to l = 60 degrees, and from b = -4 degrees to b = 4 degrees elsewhere. We detected 843 sources out of 1427 sources observed. The distributions of detected and undetecte d sources in a FIR color-color diagram show some differences, suggesti ng that more than one type of object is present in our observed sample .