1, the molecules we observe in our gas maps are not primary products directly sublimated from the nucleus, but rather are secondary, tertiary, or even higher-order products resulting from photochemical, collisional, or thermal degradation processes in the coma. Tracing the formational heritage of these molecules is non-trivial, however, insights can be gained through comparing specific line ratios and employing idealised coma models. In the following section, we present the ratio of green to red-doublet 28 forbidden oxygen [OI] emission lines to dissect the dominance of H2O vs CO2 in the coma over different heliocentric distances.

We also present the application of radial Haser profile fitting to determine possible contribution of extended sources, like icy particles or dust, to the gas morphologies we observe. Finally, we attempted to calculate gas-to-dust ratios of NH2 and CN to search for dependence on dust or signs of originating from different extended sources, however, we did not find any notable general trends preand post-perihelion.
3.3.1. G/R Ratio The ratio of green to red-doublet emission intensities can approximate if the coma is dominated by H2O, or CO2 and CO (Festou and Feldman, 1981; Decock et al., 2013; Raghuram and Bhardwaj, 2014), so long as the FoV is larger than the collisional area of the coma. We measured the intensities and calculated the ratio through a three-step process: (1) fit Gaussians to the green and red-doublets of both dust-subtracted 67P and sky-observation datacubes, (2) isolate 67P [OI] emissions by subtracting the sky [OI] emissions, and (3) compute the ratios and uncertainties. Using the dust-subtracted 67P datacubes, we independently extracted summed spectra from a 5000 km radius cometocentric circular aperture and fit a single Gaussian to each of the 5577.339, 6300.304, and 6363.776 ˚A [OI] lines. We chose a 5000 km aperture to allow for additional reference sky emission measurements to be taken from the corners of the observations, discussed in the next paragraph. We applied the same apertures and fits to the sky-observation datacubes, but also corrected for the flat sky continuum via a 1st-order polynomial subtraction in each region. We extracted fluxes from the fitted Gaussians, and summed the fluxes from the red-doublet lines. We can combine both red-doublet emissions into one channel since their intensities arise from the transition between the (2p4)1D2 state to the (2p4)3P1,2 ground states. Decock et al. (2013) noted the red-doublet intensity ratio should be synonymous with the 6300.304 and 6363.776 ˚A branching ratio, which is ∼3 as determined by Galavis et al. (1997) and Storey and Zeippen (2000) via quantum mechanical emission models. We leveraged this known ratio to check for possible NH2 contamination in our red-doublet flux, which would have artificially enhanced the red-doublet ratio to much greater than 3. We found significant contamination across several nights, which limit our sensitivity and prohibit characterisation beyond the presentation of upper limits (see Figure 10). Despite this contamination, the [OI] flux still domi29

0.25
1.9
Perihelion
1.8
Heliocentric Distance (au)
0.20
1.7
0.15
1.6
G/R
1.5
0.10
1.4
0.05
1.3 1.2
0.00
Observation Date Figure 10: Evolution of the G/R forbidden oxygen ratio over heliocentric distance. Uncertainties are reported for observations with sufficient signal and observational conditions within constraints. Upper limits are reported for observations that do not satisfy signal or observing constraints.