The discovery of the triatomic amidogen radical NH₂ in space was reported in 1993 by recent Kavli Prize recipient Ewine van Dishoeck and co-workers. The 1₁₀-1₀₁ transition of para-NH₂ was detected in emission toward the hot cores Sgr B2(M) and Sgr B2(N) with the Caltech Submillimeter Observatory. The considerable splitting of levels due to the net doublet electron spin and nuclear spin hyperfine interactions was resolved.

Later confirmation of the detection of NH₂ included several studies about a decade after the initial detection that didn't resolve the lines as well, including the work of Goicoechea et al. from 2004. Recently, Persson et al. performed high resolution studies of NH₂ toward W31C, W49N, W51, and G34.3+0.1 with the Herschel Space Observatory that provided accurate assessments of the ortho-to-para ratio of NH₂ in those sources.