The identification of interstellar nitrogen sulfide (NS) was reported in 1975 in back-to-back Letters in the Astrophysical Journal by Gottlieb et al. and Kuiper et al.. Both detections were toward Sgr B2 and were made with the 11m telescope at Kitt Peak and the 4.9m telescope at the Unversity of Texas Millimeter Wave Observatory on Mount Locke (McDonald Observatory) that operated until 1989. Confirming observations include the 1997 report by McGonagle and Irvine, which reported the observation of three rotational transitions toward twelve giant molecular clouds. NS was observed in the Seyfert galaxy NGC 253 by Martin et al. in 2003. Nitrogen sulfide was also detected in comet Hale-Bopp by Irvine et al. and in comet Hyakutake by Canaves et al.

The figures below depict the σ and π bonding in nitrogen sulfide (also known as the thionitrosyl radical) and the associated orbitals (cut-away to show the amplitude contours).

Bonding Couplings	σ - 2 e-	π - 4 e-	π* - 1 e-