Evolution of the flare X-ray emission observed by STIX and GOES. Top panel: STIX observations. STIX HXR light curves in the 6–10 (blue), 10–15 (green) and 15–25 keV (red) energy bins were derived from spectrogram data smoothed by a 48–s boxcar averaging. Bottom panel: Light curves of the GOES 0.5–4 (red) and 1–8 Å (black) SXR channels. The blue vertical line in the top panel marks the start of the impulsive flare phase, and the red line marks the first 15–25 keV peak. The green line in the bottom panel indicates the time when flare plasma appeared above the limb for GOES.