In 2018, Marcelino and co-workers confirmed the detection of N-protonated HNCO (H₂NCO⁺), which was tentatively detected in 2013 by Gupta and co-workers, a study that involved extending the rotational spectrum reported by Lattanzi and co-workers. Gupta et al. identified two rotational lines of H₂NCO⁺ toward the hot core Sgr B2(N) in data from the PRIMOS survey acquired with the Green Bank Telescope. The subsequent work of Marcelino et al. assigned six rotational transitions of H₂NCO⁺ in observations toward the hot core L483 made with the IRAM 30m telescope. Marcelino et al. also searched for the less stable O-protonated isomer, HNCOH⁺, but did not detect it.