{"assessment":{"best_window":{"end":"2026-01-24T02:00Z","end_local":"04:00","hours":2.0,"label":"good","mean_quality":0.97,"start":"2026-01-24T00:00Z","start_local":"02:00"},"cost":{"altitude":0.0,"clouds":6.0,"darkness":2.59,"moon":0.52},"formula":"astronomy = 100 * min(1, sky_hours / reference_hours) * peak_sky; overall = astronomy * score_weather / 100 (null when the weather is unknown)","hard_limit":null,"headline":"Possible, with compromises","hourly":[{"alt":null,"cloud":0,"high":0,"iso":"2026-01-23T16:00Z","label":"poor","low":0,"mid":0,"moon_alt":43,"precip":0.0,"q":0.12,"rh":95,"sky":"nautical twilight","temp":-3.6,"time":"18:00","wind":1.0},{"alt":null,"cloud":0,"high":0,"iso":"2026-01-23T17:00Z","label":"marginal","low":0,"mid":0,"moon_alt":35,"precip":0.0,"q":0.42,"rh":100,"sky":"astronomical twilight","temp":-4.7,"time":"19:00","wind":0.6},{"alt":null,"cloud":3,"high":0,"iso":"2026-01-23T18:00Z","label":"good","low":3,"mid":0,"moon_alt":26,"precip":0.0,"q":0.82,"rh":100,"sky":"night","temp":-3.2,"time":"20:00","wind":0.9},{"alt":null,"cloud":94,"high":0,"iso":"2026-01-23T19:00Z","label":"unusable","low":94,"mid":0,"moon_alt":15,"precip":0.0,"q":0.0,"rh":100,"sky":"night","temp":-4.4,"time":"21:00","wind":0.8},{"alt":null,"cloud":95,"high":23,"iso":"2026-01-23T20:00Z","label":"unusable","low":93,"mid":0,"moon_alt":5,"precip":0.0,"q":0.0,"rh":100,"sky":"night","temp":-4.7,"time":"22:00","wind":1.2},{"alt":null,"cloud":51,"high":0,"iso":"2026-01-23T21:00Z","label":"marginal","low":51,"mid":0,"moon_alt":-6,"precip":0.0,"q":0.43,"rh":100,"sky":"night","temp":-5.2,"time":"23:00","wind":1.7},{"alt":null,"cloud":76,"high":0,"iso":"2026-01-23T22:00Z","label":"poor","low":76,"mid":0,"moon_alt":-16,"precip":0.0,"q":0.16,"rh":100,"sky":"night","temp":-5.7,"time":"00:00","wind":1.8},{"alt":null,"cloud":84,"high":0,"iso":"2026-01-23T23:00Z","label":"unusable","low":84,"mid":0,"moon_alt":-26,"precip":0.0,"q":0.0,"rh":100,"sky":"night","temp":-6.3,"time":"01:00","wind":1.7},{"alt":null,"cloud":1,"high":0,"iso":"2026-01-24T00:00Z","label":"good","low":1,"mid":0,"moon_alt":-34,"precip":0.0,"q":0.99,"rh":90,"sky":"night","temp":-4.6,"time":"02:00","wind":2.2},{"alt":null,"cloud":5,"high":4,"iso":"2026-01-24T01:00Z","label":"good","low":2,"mid":0,"moon_alt":-40,"precip":0.0,"q":0.94,"rh":95,"sky":"night","temp":-6.2,"time":"03:00","wind":2.2},{"alt":null,"cloud":44,"high":31,"iso":"2026-01-24T02:00Z","label":"marginal","low":18,"mid":0,"moon_alt":-44,"precip":0.0,"q":0.51,"rh":99,"sky":"night","temp":-7.1,"time":"04:00","wind":2.6},{"alt":null,"cloud":66,"high":46,"iso":"2026-01-24T03:00Z","label":"poor","low":36,"mid":0,"moon_alt":-43,"precip":0.0,"q":0.27,"rh":100,"sky":"night","temp":-7.6,"time":"05:00","wind":2.6},{"alt":null,"cloud":81,"high":39,"iso":"2026-01-24T04:00Z","label":"unusable","low":69,"mid":0,"moon_alt":-40,"precip":0.0,"q":0.0,"rh":100,"sky":"night","temp":-7.9,"time":"06:00","wind":2.6},{"alt":null,"cloud":52,"high":12,"iso":"2026-01-24T05:00Z","label":"poor","low":45,"mid":0,"moon_alt":-33,"precip":0.0,"q":0.06,"rh":99,"sky":"nautical twilight","temp":-7.7,"time":"07:00","wind":2.1}],"peak_quality":0.99,"peak_sky":1.0,"quality_hours":5.23,"reasons":["cloud cover cost 6.0 quality-hours","daylight and twilight cost 2.6 quality-hours","moonlight cost 0.5 quality-hours"],"reference_hours":4.0,"score":47,"score_astronomy":100,"score_weather":47,"sky_hours":11.22,"verdict":"marginal","verdict_astronomy":"good","weather_known":true,"windows":[{"end":"2026-01-23T16:00Z","end_local":"18:00","hours":0.58,"label":"unusable","mean_quality":0.0,"start":"2026-01-23T15:25Z","start_local":"17:25"},{"end":"2026-01-23T16:30Z","end_local":"18:30","hours":0.5,"label":"poor","mean_quality":0.12,"start":"2026-01-23T16:00Z","start_local":"18:00"},{"end":"2026-01-23T17:05Z","end_local":"19:05","hours":0.58,"label":"marginal","mean_quality":0.42,"start":"2026-01-23T16:30Z","start_local":"18:30"},{"end":"2026-01-23T19:00Z","end_local":"21:00","hours":1.92,"label":"good","mean_quality":0.84,"start":"2026-01-23T17:05Z","start_local":"19:05"},{"end":"2026-01-23T21:00Z","end_local":"23:00","hours":2.0,"label":"unusable","mean_quality":0.0,"start":"2026-01-23T19:00Z","start_local":"21:00"},{"end":"2026-01-23T22:00Z","end_local":"00:00","hours":1.0,"label":"marginal","mean_quality":0.43,"start":"2026-01-23T21:00Z","start_local":"23:00"},{"end":"2026-01-23T23:00Z","end_local":"01:00","hours":1.0,"label":"poor","mean_quality":0.16,"start":"2026-01-23T22:00Z","start_local":"00:00"},{"end":"2026-01-24T00:00Z","end_local":"02:00","hours":1.0,"label":"unusable","mean_quality":0.0,"start":"2026-01-23T23:00Z","start_local":"01:00"},{"end":"2026-01-24T02:00Z","end_local":"04:00","hours":2.0,"label":"good","mean_quality":0.97,"start":"2026-01-24T00:00Z","start_local":"02:00"},{"end":"2026-01-24T03:00Z","end_local":"05:00","hours":1.0,"label":"marginal","mean_quality":0.51,"start":"2026-01-24T02:00Z","start_local":"04:00"},{"end":"2026-01-24T04:00Z","end_local":"06:00","hours":1.0,"label":"poor","mean_quality":0.27,"start":"2026-01-24T03:00Z","start_local":"05:00"},{"end":"2026-01-24T05:00Z","end_local":"07:00","hours":1.0,"label":"unusable","mean_quality":0.0,"start":"2026-01-24T04:00Z","start_local":"06:00"},{"end":"2026-01-24T05:15Z","end_local":"07:15","hours":0.25,"label":"poor","mean_quality":0.06,"start":"2026-01-24T05:00Z","start_local":"07:00"},{"end":"2026-01-24T05:45Z","end_local":"07:45","hours":0.5,"label":"unusable","mean_quality":0.0,"start":"2026-01-24T05:15Z","start_local":"07:15"}]},"calculation_version":"2026-10-10.1","forecast":[{"cloud":2,"dark":false,"high":0,"local":"17:00","low":2,"mid":0,"precip":0.0,"rh":89,"temp":-2.0,"time":"2026-01-23T15:00Z","wind":2.5},{"cloud":0,"dark":false,"high":0,"local":"18:00","low":0,"mid":0,"precip":0.0,"rh":95,"temp":-3.6,"time":"2026-01-23T16:00Z","wind":1.0},{"cloud":0,"dark":false,"high":0,"local":"19:00","low":0,"mid":0,"precip":0.0,"rh":100,"temp":-4.7,"time":"2026-01-23T17:00Z","wind":0.6},{"cloud":3,"dark":true,"high":0,"local":"20:00","low":3,"mid":0,"precip":0.0,"rh":100,"temp":-3.2,"time":"2026-01-23T18:00Z","wind":0.9},{"cloud":94,"dark":true,"high":0,"local":"21:00","low":94,"mid":0,"precip":0.0,"rh":100,"temp":-4.4,"time":"2026-01-23T19:00Z","wind":0.8},{"cloud":95,"dark":true,"high":23,"local":"22:00","low":93,"mid":0,"precip":0.0,"rh":100,"temp":-4.7,"time":"2026-01-23T20:00Z","wind":1.2},{"cloud":51,"dark":true,"high":0,"local":"23:00","low":51,"mid":0,"precip":0.0,"rh":100,"temp":-5.2,"time":"2026-01-23T21:00Z","wind":1.7},{"cloud":76,"dark":true,"high":0,"local":"00:00","low":76,"mid":0,"precip":0.0,"rh":100,"temp":-5.7,"time":"2026-01-23T22:00Z","wind":1.8},{"cloud":84,"dark":true,"high":0,"local":"01:00","low":84,"mid":0,"precip":0.0,"rh":100,"temp":-6.3,"time":"2026-01-23T23:00Z","wind":1.7},{"cloud":1,"dark":true,"high":0,"local":"02:00","low":1,"mid":0,"precip":0.0,"rh":90,"temp":-4.6,"time":"2026-01-24T00:00Z","wind":2.2},{"cloud":5,"dark":true,"high":4,"local":"03:00","low":2,"mid":0,"precip":0.0,"rh":95,"temp":-6.2,"time":"2026-01-24T01:00Z","wind":2.2},{"cloud":44,"dark":true,"high":31,"local":"04:00","low":18,"mid":0,"precip":0.0,"rh":99,"temp":-7.1,"time":"2026-01-24T02:00Z","wind":2.6},{"cloud":66,"dark":true,"high":46,"local":"05:00","low":36,"mid":0,"precip":0.0,"rh":100,"temp":-7.6,"time":"2026-01-24T03:00Z","wind":2.6},{"cloud":81,"dark":true,"high":39,"local":"06:00","low":69,"mid":0,"precip":0.0,"rh":100,"temp":-7.9,"time":"2026-01-24T04:00Z","wind":2.6},{"cloud":52,"dark":false,"high":12,"local":"07:00","low":45,"mid":0,"precip":0.0,"rh":99,"temp":-7.7,"time":"2026-01-24T05:00Z","wind":2.1},{"cloud":43,"dark":false,"high":19,"local":"08:00","low":30,"mid":0,"precip":0.0,"rh":94,"temp":-6.3,"time":"2026-01-24T06:00Z","wind":2.0}],"forecast_source":"history","forecast_updated_at":"2026-10-17T10:38:16Z","limits":{"good_alt":30.0,"usable_alt":20.0},"night":{"dark_from":"2026-01-23T17:01:55Z","dark_hours":11.03,"dark_to":"2026-01-24T04:03:40Z","moon":{"illumination":0.259,"phase":"waxing crescent","waxing":true},"moon_free_dark_hours":7.6,"moonrise":"2026-01-24T08:23:01Z","moonset":"2026-01-23T20:26:05Z","sunrise":"2026-01-24T05:40:22Z","sunset":"2026-01-23T15:25:00Z","twilight":{"astronomical":{"end":"2026-01-23T17:01:55Z","start":"2026-01-24T04:03:40Z"},"civil":{"end":"2026-01-23T15:55:07Z","start":"2026-01-24T05:10:20Z"},"nautical":{"end":"2026-01-23T16:28:56Z","start":"2026-01-24T04:36:35Z"}},"window_end":"2026-01-24T10:00:00Z","window_start":"2026-01-23T10:00:00Z"},"night_date":"2026-01-23","site":{"elev_m":1750,"lat":41.693,"lon":24.739,"name":"NAO Rozhen"},"warnings":[]}