586 frames, 20:11 to 05:55 (London time). Darkest sky 5.30 stops above black (17.2 mag/arcsec²), so clear.
astrocam v3 · night of 18 Sep 2026
Sky brightness of every frame (log₂: one stop is twice the light). Dusk and dawn are the slopes at each end; cloud shows as a bump. The star-trail stack uses only frames within 30% of the darkest 10 minutes, so twilight and cloud are left out of it. Left out is not thrown away: those frames still go into the videos.