Log-linear plot of the HO/HO absorption line area ratio as a function of continuum temperature for 101 different production rates (10²⁴–10²⁹ molecules s^-1 from top to bottom). For each production rate, as the continuum temperature increases, the ratio between the two absorption lines also increases. The measured ratio and continuum temperature from the MIRO dataset (grey points) can be used to derive estimates for the production rate from these curves.