{"assessment":{"best_window":{"end":"2025-12-22T18:00Z","end_local":"20:00","hours":1.42,"label":"good","mean_quality":0.71,"start":"2025-12-22T16:35Z","start_local":"18:35"},"cost":{"altitude":0.0,"clouds":10.97,"darkness":2.74,"moon":0.02},"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 11.3 of 13.8 dark hours \u2014 the sky is closed whatever the geometry says.","headline":"Barely","hourly":[{"alt":null,"cloud":16,"high":0,"iso":"2025-12-22T15:00Z","label":"unusable","low":16,"mid":0,"moon_alt":15,"precip":0.0,"q":0.0,"rh":87,"sky":"civil twilight","temp":-2.4,"time":"17:00","wind":3.4},{"alt":null,"cloud":21,"high":0,"iso":"2025-12-22T16:00Z","label":"poor","low":21,"mid":0,"moon_alt":7,"precip":0.0,"q":0.11,"rh":92,"sky":"nautical twilight","temp":-3.3,"time":"18:00","wind":1.7},{"alt":null,"cloud":27,"high":0,"iso":"2025-12-22T17:00Z","label":"good","low":27,"mid":0,"moon_alt":-1,"precip":0.0,"q":0.7,"rh":97,"sky":"night","temp":-4.0,"time":"19:00","wind":0.6},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-22T18:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-11,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-3.2,"time":"20:00","wind":1.2},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-22T19:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-21,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-3.0,"time":"21:00","wind":2.3},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-22T20:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-31,"precip":0.0,"q":0.0,"rh":100,"sky":"night","temp":-3.0,"time":"22:00","wind":1.7},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-22T21:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-42,"precip":0.0,"q":0.0,"rh":100,"sky":"night","temp":-3.9,"time":"23:00","wind":0.4},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-22T22:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-52,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-4.5,"time":"00:00","wind":0.8},{"alt":null,"cloud":98,"high":0,"iso":"2025-12-22T23:00Z","label":"unusable","low":98,"mid":0,"moon_alt":-62,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-4.7,"time":"01:00","wind":1.5},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-23T00:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-69,"precip":0.0,"q":0.0,"rh":100,"sky":"night","temp":-2.8,"time":"02:00","wind":2.5},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-23T01:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-70,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-2.7,"time":"03:00","wind":2.6},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-23T02:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-65,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-2.8,"time":"04:00","wind":1.8},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-23T03:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-57,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-4.1,"time":"05:00","wind":1.7},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-23T04:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-46,"precip":0.0,"q":0.0,"rh":99,"sky":"night","temp":-4.6,"time":"06:00","wind":3.0},{"alt":null,"cloud":100,"high":0,"iso":"2025-12-23T05:00Z","label":"unusable","low":100,"mid":0,"moon_alt":-36,"precip":0.0,"q":0.0,"rh":99,"sky":"nautical twilight","temp":-5.0,"time":"07:00","wind":2.4}],"peak_quality":0.77,"peak_sky":1.0,"quality_hours":1.27,"reasons":["cloud cover cost 11.0 quality-hours","daylight and twilight cost 2.7 quality-hours"],"reference_hours":4.0,"score":10,"score_astronomy":100,"score_weather":10,"sky_hours":12.24,"verdict":"poor","verdict_astronomy":"good","weather_known":true,"windows":[{"end":"2025-12-22T15:30Z","end_local":"17:30","hours":0.67,"label":"unusable","mean_quality":0.0,"start":"2025-12-22T14:50Z","start_local":"16:50"},{"end":"2025-12-22T16:05Z","end_local":"18:05","hours":0.58,"label":"poor","mean_quality":0.12,"start":"2025-12-22T15:30Z","start_local":"17:30"},{"end":"2025-12-22T16:35Z","end_local":"18:35","hours":0.5,"label":"marginal","mean_quality":0.37,"start":"2025-12-22T16:05Z","start_local":"18:05"},{"end":"2025-12-22T18:00Z","end_local":"20:00","hours":1.42,"label":"good","mean_quality":0.71,"start":"2025-12-22T16:35Z","start_local":"18:35"},{"end":"2025-12-23T05:50Z","end_local":"07:50","hours":11.83,"label":"unusable","mean_quality":0.0,"start":"2025-12-22T18:00Z","start_local":"20:00"}]},"calculation_version":"2026-10-10.1","forecast":[{"cloud":84,"dark":false,"high":0,"local":"16:00","low":84,"mid":0,"precip":0.0,"rh":73,"temp":-0.3,"time":"2025-12-22T14:00Z","wind":4.9},{"cloud":16,"dark":false,"high":0,"local":"17:00","low":16,"mid":0,"precip":0.0,"rh":87,"temp":-2.4,"time":"2025-12-22T15:00Z","wind":3.4},{"cloud":21,"dark":false,"high":0,"local":"18:00","low":21,"mid":0,"precip":0.0,"rh":92,"temp":-3.3,"time":"2025-12-22T16:00Z","wind":1.7},{"cloud":27,"dark":true,"high":0,"local":"19:00","low":27,"mid":0,"precip":0.0,"rh":97,"temp":-4.0,"time":"2025-12-22T17:00Z","wind":0.6},{"cloud":100,"dark":true,"high":0,"local":"20:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-3.2,"time":"2025-12-22T18:00Z","wind":1.2},{"cloud":100,"dark":true,"high":0,"local":"21:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-3.0,"time":"2025-12-22T19:00Z","wind":2.3},{"cloud":100,"dark":true,"high":0,"local":"22:00","low":100,"mid":0,"precip":0.0,"rh":100,"temp":-3.0,"time":"2025-12-22T20:00Z","wind":1.7},{"cloud":100,"dark":true,"high":0,"local":"23:00","low":100,"mid":0,"precip":0.0,"rh":100,"temp":-3.9,"time":"2025-12-22T21:00Z","wind":0.4},{"cloud":100,"dark":true,"high":0,"local":"00:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-4.5,"time":"2025-12-22T22:00Z","wind":0.8},{"cloud":98,"dark":true,"high":0,"local":"01:00","low":98,"mid":0,"precip":0.0,"rh":99,"temp":-4.7,"time":"2025-12-22T23:00Z","wind":1.5},{"cloud":100,"dark":true,"high":0,"local":"02:00","low":100,"mid":0,"precip":0.0,"rh":100,"temp":-2.8,"time":"2025-12-23T00:00Z","wind":2.5},{"cloud":100,"dark":true,"high":0,"local":"03:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-2.7,"time":"2025-12-23T01:00Z","wind":2.6},{"cloud":100,"dark":true,"high":0,"local":"04:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-2.8,"time":"2025-12-23T02:00Z","wind":1.8},{"cloud":100,"dark":true,"high":0,"local":"05:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-4.1,"time":"2025-12-23T03:00Z","wind":1.7},{"cloud":100,"dark":true,"high":0,"local":"06:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-4.6,"time":"2025-12-23T04:00Z","wind":3.0},{"cloud":100,"dark":false,"high":0,"local":"07:00","low":100,"mid":0,"precip":0.0,"rh":99,"temp":-5.0,"time":"2025-12-23T05:00Z","wind":2.4},{"cloud":94,"dark":false,"high":0,"local":"08:00","low":94,"mid":0,"precip":0.0,"rh":99,"temp":-4.5,"time":"2025-12-23T06:00Z","wind":2.9}],"forecast_source":"history","forecast_updated_at":"2026-10-18T11:22:28Z","limits":{"good_alt":30.0,"usable_alt":20.0},"night":{"dark_from":"2025-12-22T16:34:43Z","dark_hours":11.51,"dark_to":"2025-12-23T04:05:09Z","moon":{"illumination":0.077,"phase":"waxing crescent","waxing":true},"moon_free_dark_hours":11.2,"moonrise":"2025-12-23T08:24:59Z","moonset":"2025-12-22T16:52:07Z","sunrise":"2025-12-23T05:45:40Z","sunset":"2025-12-22T14:54:11Z","twilight":{"astronomical":{"end":"2025-12-22T16:34:43Z","start":"2025-12-23T04:05:09Z"},"civil":{"end":"2025-12-22T15:25:47Z","start":"2025-12-23T05:14:05Z"},"nautical":{"end":"2025-12-22T16:00:51Z","start":"2025-12-23T04:39:01Z"}},"window_end":"2025-12-23T10:00:00Z","window_start":"2025-12-22T10:00:00Z"},"night_date":"2025-12-22","site":{"elev_m":1750,"lat":41.693,"lon":24.739,"name":"NAO Rozhen"},"warnings":[]}