HSC about 166 kJ/mol higher in energy than HCS according to ab initio calculations in
(1) C. Ochsenfeld, R. I. Kaiser, Y. T. Lee, and M. Head-Gordon, 1999, J. Chem. Phys. 110, 9982.
Nevertheless, it has been observed in the laboratory by
(2) H. Habara and S. Yamamoto, 2000, J. Chem. Phys. 112, 10905.
The total dipole moment is from an ab initio calculation in (1). The a and b components were derived in (2) from relative intensity measurements. The uncertainties are probably several percent.