Disambiguation of cool and hot emission in IRIS/Slit-Jaw Imager and AIA channels

Abstract Accurate temperature diagnostics of the solar corona are necessary for detecting the heating and cooling processes, and better understanding the conversion of the magnetic energy into thermal energy. A major obstacle in this enterprise is the multi-temperature emission contained in Ultra Violet (UV) and Extreme UV (EUV) passbands such as those of the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO) and the Slit-Jaw Imager (SJI) of the Interface Region Imaging Spectrograph (IRIS). In this work we extend the Response Fitting (RFit) method to disambiguate between cool, warm and hot emission in the SDO/AIA and IRIS/SJI passbands. We improve previous results for AIA~304~\, and find very good cool/hot decomposition for AIA~94~\, allowing to improve previous empirical disambiguation methods for this passband. The hot temperature coverage of AIA allows RFit to be applied across instruments. This allows to diambiguate the hot flaring emission from {Fe}{XXI} contained within the SJI~1330~\, and SJI~1400~\, passbands, supported by IRIS/SG results. We also find ways to constrain to some degree of accuracy the hot emission in AIA~211~, and the very hot (flaring) emission in AIA~131~\, and AIA~193~. We apply RFit to an AIA-IRIS co-observation that includes a flare, and calculate the average relative contribution for the cool-hot emission to find 10/90, 17/83, 68/32, 62/38, respectively, for AIA~304~, AIA~94~, SJI~1330~\, and SJI~1400~. We obtain a more coherent picture of the hot temperature evolution in the log T =6.8-7.15 temperature range and its spatial localisation during the flare. We further accurately detect and quantify the cool plasma from coronal rain, which is observed to increase ten-fold due to the flare-driven cooling.