Radiation temperature maps of the ALMA 1.3 mm (panel a) and of a few IRIS line features at UV wavelengths: line core of C II 133.4 nm (panel c); blue emission peak, line core, and red emission peak of Mg II k 279.6 nm (panels d–f) and of Mg II h 280.4 nm (panels g–i). For comparison, line-core intensity of the IRIS Si IV 139.4 nm is illustrated in panel c. Blue pixels are regions where the corresponding line features could not be determined.