Automatic twilight watch for noctilucent clouds (NLC) — the highest clouds in the atmosphere, ~76–85 km up, glowing electric-blue in deep twilight.
NLCs only appear when the Sun is 6–16° below the horizon — you are in darkness, but the clouds, far above the weather, are still lit from below. They sit low toward the Sun's azimuth: in summer that means the NW→N at dusk and the N→NE at dawn. This camera scans exactly that band on every twilight frame and flags any feature that is blue, brighter than the smooth twilight glow, and finely structured.
Honest note: this all-sky lens only sees the sky down to ~20° above the horizon, so only the upper part of a strong display (mainly to the NW at dusk) can be caught here. Flagged frames are candidates — the thumbnails below let you confirm by eye.
Share of the twilight band that looks like NLC · a candidate is flagged above the dashed line
Thumbnails of the NW/N twilight band whenever a candidate was flagged · newest first
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