Temperature response functions for the AIA 304 Å and IRIS 1400 Å channels. It is worth noting that the response function was calculated based on the CHIANTI database, which has been known to fail at reproducing the He II intensity peak between 10^4.8–10^4.9 K, where the resulting peak is an order of magnitude lower. This is likely due to the effects of non-equilibrium ionisation in tandem with optically thick radiative transfer in the He II line causing these large intensities (Golding et al. 2017). To account for this, the AIA 304 Å response function has been multiplied by an empirical factor of 5 (O’Dwyer et al. 2010).