G/R ratio for each subslit spectrum for comet 73P-C/ Schwassmann-Wachmann 3. The range of nucleocentric distances covered by each point is indicated. The model-calculated G/R ratio as a function of projected distance is plotted with a solid curve. An H₂O production rate of 1.7 × 10²⁸ s^-1 and 0.5% CO relative abundance were used. The fit gives the CO₂ relative abundance of the comet. The blue dash-dotted curve represents the calculated G/R ratio not accounting for collisional quenching with 0% CO₂ relative abundance.