Experimental spectrum recorded around the N′ − N″ = 17 − 16 a-type transition of H₂NCO using Zeeman modulation spectroscopy (upper trace), and comparison with PGOPHER simulations for υ = 0 and the three lowest vibrationally excited states at 300 K. The simulation in υ = 0 was obtained using the final set of spectroscopic parameters (see Table 1). Those in the excited states were obtained using the harmonic vibrational energies, the predicted rotational constants in these states (calculated using the α values in Table A.2), and the other spectroscopic parameters from υ = 0. For all simulations, a Gaussian profile with a full width at half maximum of 1.3 MHz has been used. Shaded areas in the upper trace highlight regions where the observed transitions likely arise from vibrational satellites.