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We present joint Hinode/EIS and IRIS observations of Fe XII lines in activeregions, both on-disk and off-limb. We use an improved calibration for the EISdata, and find that the 192.4 A / 1349 A observed ratio is consistent with thevalues predicted by CHIANTI and the coronal approximation in quiescent areas,but not in all active region observations, where the ratio is often lower thanexpected by up to a factor of about two. We investigate a number of physicalmechanisms that could affect this ratio, such as opacity and absorption fromcooler material. We find significant opacity in the EIS Fe XII 193 and 195 Alines, but not in the 192.4 A line, in agreement with previous findings. As wecannot rule out possible EUV absorption by H, He and He II in the on-diskobservations, we focus on an off-limb observation where such absorption isminimal. After considering these, as well as possible non-equilibrium effects,we suggest that the most likely explanation for the observed low Fe XII 192.4 A/ 1349 A ratio is the presence of non-Maxwellian electron distributions in theactive regions. This is in agreement with previous findings based on EIS andIRIS observations independently.

Diagnostics of non-Maxwellian electron distributions in solar active regions from Fe XII lines observed by Hinode/EIS and IRIS