Studies of dense molecular cores in regions of massive star formation. IV. Multitransition CS-study towards

We have observed CS and C34S emission towards 33 H2O maser positions in the southern sky () using the SEST telescope. Most of the sources were selected also for their association with strong IRAS sources. CS(2-1) was detected in all sources, with the possible exception of two. Most sources were also mapped in the transitions CS(5-4) and C34S(2-1) and half of the sample also in CS(2-1). CS and C34S transitions were measured towards the centres of the clouds as determined from the mapping. CS and C34S transitions were measured in about a half dozen clouds. CO(1-0) was measured in most clouds in order to determine the kinetic temperatures. The CS column densities were calculated using the LTE approximation. All measurements were also analyzed using a spherical LVG model. We present the observational data and the results of this analysis.