Synthetic spectra of the P-branch (ΔJ = −1), c-type transitions of CH₂CNH overlaid on the GBT spectrum of Sgr B2. Transition quantum numbers are at the bottom of each spectrum. The synthetic spectra for the Sgr B2(N) components (red curve) were generated from the physical conditions and observing parameters described in Sect. 4.1 (i.e., T_ex = 5.8 K, source size= 20″, N_T ~ 1.8 × 10¹⁶ cm⁻²). An additional contribution to the 4930 MHz absorption feature (gray curve) was modeled assuming the same T_ex and source size as that of Sgr B2(N), a v_LSR of +63 km s⁻¹, dV of 17 km s⁻¹, and N_T of ~1.75 × 10¹⁷ cm⁻². The sum of the synthetic absorption lines are shown by the green curve.