Model fit of the synthetic (red) to observed (black) TEXES spectrum near 12 μm, including the 1σ error envelope in blue. Corresponding wavelengths in microns are shown on the upper horizontal axis. The green line is the fit with emission from propadiene not included in the model to clearly show the emission from propadiene. The brightest non-labeled emission features are from C₂H₆. The inset in the top right shows an enlarged view of the propadiene emission. Prominent emission from ¹³C¹²CH₆ are denoted by diamonds. C₃H₈ is also included in the model; however, it does not show any noticeable emission features in this region.