The experimental lines are from
(1) M. Winnewisser and E. Schäfer, 1980, Z. Naturforsch. 35a, 483.
Some higher order centrifugal distortion constants are estimated.
At low temperatures, it may be necessary to discern between ortho-H2C2S and para-H2C2S. The ortho states are described by Ka odd, the para states by Ka even. The nuclear spin-weights are 3 and 1 for ortho-H2C2S and para-H2C2S, respectively. The JKaKc = 111 level is the lowest ortho level. It is 9.7470 cm–1 above ground.
The dipole moment is from the same work.