Deuterium hyperfine structure in interstellar C3HD. 
The deuterium nuclear quadrupole hyperfine structure of the transition 1(10)-1(01) of the ring molecule cyclopropenylidene-d1 (C3HD) has been observed in emission from interstellar molecular clouds.  The narrowest linewidths (approximately 7 kHz) so far observed are in the cloud L1498.  The derived D coupling constants Xzz = 186.9(1.4) kHz, eta=0.063(18) agree well with correlations based on other molecules.