Synthetic spectrum of C₂H₅CHNH. The E isomer transitions are presented in the first column in panels a–e (in magenta) and the Z isomer transitions are presented in the second column in panels ƒ–j (in cyan). The spectrum was generated from the physical conditions and observing parameters described in Sect. 4.1 (i.e., T_ex = 5.8 K, source size of 20″, N_T ~ 1.5 × 10¹³ cm⁻² for the E isomer and N_T ~ 1.0 × 10¹³ cm⁻² for the Z isomer) overlaid on the GBT spectrum of Sgr B2(LMH) shown in black. Transition quantum numbers and upper state energy levels are at the bottom of each spectrum. No significant emission from C₂H₅CHNH transitions are detected beyond the 3σ upper limit. Panels g and j have an ordinate range between −0.1 and 0.1 K due to the noise level in the spectrum.