Although not quite as frequently as di-oxygen, sulfur monoxide has been studied extensively, especially by the astronomy community. It is involved in several photochemical processes in the atmosphere of Io (one of Jupiter's moons), where it is believed to be generated from Pele-type volcanic activity. In Io's exosphere and the interstellar space, photoionization of SO results in the formation of SO + . SO has also been detected in the Hale-Bopp comet, while in the interstellar media, it is present in Orion A,  Ophiuchi, Sagittarius B2, and many others. In Earth's atmosphere, SO is commonly produced by ultraviolet photolysis of SO2. It plays a role in oxidizing sulfur dioxide (SO2) and sulfur trioxide (SO3), both components in acid rain and cloud condensation nuclei that contribute to the global sulfur cycle. There have been several experimental and theoretical studies on the electronic states of SO and SO  , while Lineberger and coworkers used photoelectron spectroscopy to study SO  . They obtained the high-resolution photoelectron spectrum including the SO  (X 2 )  SO(X 3   , a 1 , b 1   ) photodetachment transitions and determined the adiabatic electron affinity (EA) of SO to be 1.125 (5) eV. Here, we revisit these latter transitions focusing on the corresponding PADs.