Mid-infrared spectra of IRc2 near the Orion Nebula (M42 or NGC 1976). Upper panel: SOFIA observational data (black lines). Middle panel: C₂H₂ absorption lines corresponding to R-branch. Lower panel: ¹³CCH₂ absorption lines corresponding to R-branch. Vertical lines correspond to the HITRAN database (solid), the LSR corrections (dashed), and corrections for both the LSR and Doppler effects (dash-dotted). The shading around the dash-dotted lines represents the error associated with the transformation to the LSR.