{"assessment":{"best_window":null,"cost":{"altitude":0.0,"clouds":3.72,"darkness":2.5,"moon":7.77},"formula":"astronomy = 100 * min(1, sky_hours / reference_hours) * peak_sky; overall = astronomy * score_weather / 100 (null when the weather is unknown)","hard_limit":"Overcast (\u226580 % cloud) for 13.0 of 13.0 dark hours \u2014 the sky is closed whatever the geometry says.","headline":"Not tonight","hourly":[{"alt":null,"cloud":100,"high":1,"iso":"2026-01-31T16:00Z","label":"unusable","low":100,"mid":82,"moon_alt":21,"precip":0.4,"q":0.0,"rh":96,"sky":"civil twilight","temp":-2.6,"time":"18:00","wind":3.0},{"alt":null,"cloud":100,"high":0,"iso":"2026-01-31T17:00Z","label":"unusable","low":100,"mid":53,"moon_alt":31,"precip":0.5,"q":0.0,"rh":98,"sky":"astronomical twilight","temp":-2.9,"time":"19:00","wind":2.6},{"alt":null,"cloud":100,"high":0,"iso":"2026-01-31T18:00Z","label":"unusable","low":100,"mid":27,"moon_alt":42,"precip":0.3,"q":0.0,"rh":100,"sky":"night","temp":-2.8,"time":"20:00","wind":4.2},{"alt":null,"cloud":100,"high":0,"iso":"2026-01-31T19:00Z","label":"unusable","low":100,"mid":18,"moon_alt":53,"precip":0.5,"q":0.0,"rh":99,"sky":"night","temp":-2.8,"time":"21:00","wind":5.5},{"alt":null,"cloud":100,"high":0,"iso":"2026-01-31T20:00Z","label":"unusable","low":100,"mid":1,"moon_alt":63,"precip":0.1,"q":0.0,"rh":99,"sky":"night","temp":-2.9,"time":"22:00","wind":5.3},{"alt":null,"cloud":100,"high":0,"iso":"2026-01-31T21:00Z","label":"unusable","low":100,"mid":0,"moon_alt":70,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-3.1,"time":"23:00","wind":5.0},{"alt":null,"cloud":100,"high":4,"iso":"2026-01-31T22:00Z","label":"unusable","low":100,"mid":0,"moon_alt":71,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-3.2,"time":"00:00","wind":4.9},{"alt":null,"cloud":100,"high":54,"iso":"2026-01-31T23:00Z","label":"unusable","low":100,"mid":0,"moon_alt":66,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-3.4,"time":"01:00","wind":5.4},{"alt":null,"cloud":100,"high":5,"iso":"2026-02-01T00:00Z","label":"unusable","low":100,"mid":0,"moon_alt":56,"precip":0.0,"q":0.0,"rh":98,"sky":"night","temp":-2.9,"time":"02:00","wind":6.1},{"alt":null,"cloud":100,"high":90,"iso":"2026-02-01T01:00Z","label":"unusable","low":100,"mid":2,"moon_alt":46,"precip":0.2,"q":0.0,"rh":98,"sky":"night","temp":-3.1,"time":"03:00","wind":6.9},{"alt":null,"cloud":100,"high":100,"iso":"2026-02-01T02:00Z","label":"unusable","low":100,"mid":30,"moon_alt":35,"precip":0.1,"q":0.0,"rh":99,"sky":"night","temp":-3.4,"time":"04:00","wind":7.1},{"alt":null,"cloud":100,"high":100,"iso":"2026-02-01T03:00Z","label":"unusable","low":100,"mid":100,"moon_alt":24,"precip":0.1,"q":0.0,"rh":98,"sky":"night","temp":-3.7,"time":"05:00","wind":7.6},{"alt":null,"cloud":100,"high":100,"iso":"2026-02-01T04:00Z","label":"unusable","low":100,"mid":99,"moon_alt":13,"precip":0.0,"q":0.0,"rh":98,"sky":"astronomical twilight","temp":-4.0,"time":"06:00","wind":8.6},{"alt":null,"cloud":100,"high":100,"iso":"2026-02-01T05:00Z","label":"unusable","low":100,"mid":99,"moon_alt":3,"precip":0.0,"q":0.0,"rh":98,"sky":"nautical twilight","temp":-4.5,"time":"07:00","wind":7.6}],"peak_quality":0.0,"peak_sky":0.51,"quality_hours":0.0,"reasons":["moonlight cost 7.8 quality-hours","cloud cover cost 3.7 quality-hours","daylight and twilight cost 2.5 quality-hours"],"reference_hours":4.0,"score":0,"score_astronomy":47,"score_weather":0,"sky_hours":3.72,"verdict":"unusable","verdict_astronomy":"marginal","weather_known":true,"windows":[{"end":"2026-02-01T05:35Z","end_local":"07:35","hours":14.0,"label":"unusable","mean_quality":0.0,"start":"2026-01-31T15:35Z","start_local":"17:35"}]},"calculation_version":"2026-10-10.1","forecast":[{"cloud":100,"dark":false,"high":16,"local":"17:00","low":100,"mid":100,"precip":0.2,"rh":94,"temp":-2.3,"time":"2026-01-31T15:00Z","wind":4.8},{"cloud":100,"dark":false,"high":1,"local":"18:00","low":100,"mid":82,"precip":0.4,"rh":96,"temp":-2.6,"time":"2026-01-31T16:00Z","wind":3.0},{"cloud":100,"dark":false,"high":0,"local":"19:00","low":100,"mid":53,"precip":0.5,"rh":98,"temp":-2.9,"time":"2026-01-31T17:00Z","wind":2.6},{"cloud":100,"dark":true,"high":0,"local":"20:00","low":100,"mid":27,"precip":0.3,"rh":100,"temp":-2.8,"time":"2026-01-31T18:00Z","wind":4.2},{"cloud":100,"dark":true,"high":0,"local":"21:00","low":100,"mid":18,"precip":0.5,"rh":99,"temp":-2.8,"time":"2026-01-31T19:00Z","wind":5.5},{"cloud":100,"dark":true,"high":0,"local":"22:00","low":100,"mid":1,"precip":0.1,"rh":99,"temp":-2.9,"time":"2026-01-31T20:00Z","wind":5.3},{"cloud":100,"dark":true,"high":0,"local":"23:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-3.1,"time":"2026-01-31T21:00Z","wind":5.0},{"cloud":100,"dark":true,"high":4,"local":"00:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-3.2,"time":"2026-01-31T22:00Z","wind":4.9},{"cloud":100,"dark":true,"high":54,"local":"01:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-3.4,"time":"2026-01-31T23:00Z","wind":5.4},{"cloud":100,"dark":true,"high":5,"local":"02:00","low":100,"mid":0,"precip":0.0,"rh":98,"temp":-2.9,"time":"2026-02-01T00:00Z","wind":6.1},{"cloud":100,"dark":true,"high":90,"local":"03:00","low":100,"mid":2,"precip":0.2,"rh":98,"temp":-3.1,"time":"2026-02-01T01:00Z","wind":6.9},{"cloud":100,"dark":true,"high":100,"local":"04:00","low":100,"mid":30,"precip":0.1,"rh":99,"temp":-3.4,"time":"2026-02-01T02:00Z","wind":7.1},{"cloud":100,"dark":true,"high":100,"local":"05:00","low":100,"mid":100,"precip":0.1,"rh":98,"temp":-3.7,"time":"2026-02-01T03:00Z","wind":7.6},{"cloud":100,"dark":false,"high":100,"local":"06:00","low":100,"mid":99,"precip":0.0,"rh":98,"temp":-4.0,"time":"2026-02-01T04:00Z","wind":8.6},{"cloud":100,"dark":false,"high":100,"local":"07:00","low":100,"mid":99,"precip":0.0,"rh":98,"temp":-4.5,"time":"2026-02-01T05:00Z","wind":7.6},{"cloud":100,"dark":false,"high":100,"local":"08:00","low":100,"mid":100,"precip":0.0,"rh":98,"temp":-4.8,"time":"2026-02-01T06:00Z","wind":9.0}],"forecast_source":"history","forecast_updated_at":"2026-10-17T12:13:03Z","limits":{"good_alt":30.0,"usable_alt":20.0},"night":{"dark_from":"2026-01-31T17:10:36Z","dark_hours":10.79,"dark_to":"2026-02-01T03:58:01Z","moon":{"illumination":0.986,"phase":"full moon","waxing":true},"moon_free_dark_hours":0.0,"moonrise":"2026-01-31T13:52:20Z","moonset":"2026-02-01T05:19:32Z","sunrise":"2026-02-01T05:33:18Z","sunset":"2026-01-31T15:35:05Z","twilight":{"astronomical":{"end":"2026-01-31T17:10:36Z","start":"2026-02-01T03:58:01Z"},"civil":{"end":"2026-01-31T16:04:36Z","start":"2026-02-01T05:03:52Z"},"nautical":{"end":"2026-01-31T16:37:56Z","start":"2026-02-01T04:30:37Z"}},"window_end":"2026-02-01T10:00:00Z","window_start":"2026-01-31T10:00:00Z"},"night_date":"2026-01-31","site":{"elev_m":1750,"lat":41.693,"lon":24.739,"name":"NAO Rozhen"},"warnings":[]}