SIMBAD references

We present the most extensive survey to date of the SO ground state transition J_K=1₀-0₁(30 GHz). We observed 49 regions of massive star formation with the Max-Planck-Institut für Radioastronomie (MPIfR) 100 m telescope. In addition, the SO J_K=4₃-3₂transition was observed with the IRAM 30 m telescope toward a subsample of seven sources. Emission in the SO J_K=1₀-0₁transition most likely arises from the parsec-scale molecular clumps surrounding ultracompact H II regions. In general, the SO J_K=1₀-0₁ line has a Gaussian shape and appears to be optically thin. We derive SO column densities between 0.58x10¹⁴ and 12x10¹⁴/cm2 and SO abundances in the range 0.18x10^–9-4.4x10^–9. Our observations show that the SO ground state transition is an effective tool to study massive star-forming clumps, and the data presented in this paper provide a useful supplement for future multitransition SO studies.