OH-OBSERVATIONS AND HI-OBSERVATIONS OF THE CRA DARK CLOUD COMPLEX

We present OH 1667-MHz observations covering the CrA dark cloud complex as well as HI 21-cm observations in a large region around the complex. The OH profiles are of simple structure indicating the presence of only one component with a mean velocity V(OH) congruent-to +5.5 km s-1. Three OH clumps are apparent, which are coincident with regions of high photographic extinction. The gas to dust ratio derived from these observations is similar to the average value obtained for other dark clouds and shows that OH and dust are well mixed in the CrA dark cloud complex. The total mass estimated for the molecular cloud amounts to M(T) congruent-to 7 x 10(3)M.. The HI observations show the well-known ridge of local gas of low positive velocities. The accordance between the velocities of molecular and atomic gas in the region suggests that the molecular complex is embedded in the local HI-ridge. We suggest that they both are related to Lindbald's feature A, i.e. to Gould's belt.