Light curves in several wavelength bands corresponding to spatially integrated emission (panel a) and pixels co-spatial with the pixel No. 53 along the IRIS slit (panels b–e). Panel a: Konus count rate in the G1 channel and GOES time derivative. Panel b: Emission in several SDO/AIA filters with the 1600 Å filter data scaled by ten for plotting purposes. Panels c and d: calibrated intensity averaged in the IRIS spectral bands A, B, C (panel c; continuum emission), D, and E (panel d; line emission). Panel e: Emission relative to the quiet-Sun values in several GREGOR HiFI+ filters. The preflare time interval for evaluating the IRIS C band preflare emission is delimited by two solid vertical lines in panel c). The vertical dotted line indicates the start of the last HXR pulse.