{"assessment":{"best_window":{"end":"2027-09-16T21:40Z","end_local":"00:40","hours":3.58,"label":"marginal","mean_quality":0.38,"start":"2027-09-16T18:05Z","start_local":"21:05"},"cost":{"altitude":0.0,"clouds":0.0,"darkness":2.53,"moon":5.91},"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":"Astronomically barely \u2014 weather unknown","hourly":[{"alt":null,"cloud":null,"high":null,"iso":"2027-09-16T17:00Z","label":"poor","low":null,"mid":null,"moon_alt":6,"precip":null,"q":0.08,"rh":null,"sky":"nautical twilight","temp":null,"time":"20:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-16T18:00Z","label":"poor","low":null,"mid":null,"moon_alt":17,"precip":null,"q":0.25,"rh":null,"sky":"astronomical twilight","temp":null,"time":"21:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-16T19:00Z","label":"marginal","low":null,"mid":null,"moon_alt":27,"precip":null,"q":0.42,"rh":null,"sky":"night","temp":null,"time":"22:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-16T20:00Z","label":"marginal","low":null,"mid":null,"moon_alt":37,"precip":null,"q":0.36,"rh":null,"sky":"night","temp":null,"time":"23:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-16T21:00Z","label":"marginal","low":null,"mid":null,"moon_alt":46,"precip":null,"q":0.32,"rh":null,"sky":"night","temp":null,"time":"00:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-16T22:00Z","label":"poor","low":null,"mid":null,"moon_alt":52,"precip":null,"q":0.29,"rh":null,"sky":"night","temp":null,"time":"01:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-16T23:00Z","label":"poor","low":null,"mid":null,"moon_alt":54,"precip":null,"q":0.29,"rh":null,"sky":"night","temp":null,"time":"02:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-17T00:00Z","label":"poor","low":null,"mid":null,"moon_alt":51,"precip":null,"q":0.3,"rh":null,"sky":"night","temp":null,"time":"03:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-17T01:00Z","label":"marginal","low":null,"mid":null,"moon_alt":44,"precip":null,"q":0.33,"rh":null,"sky":"night","temp":null,"time":"04:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-17T02:00Z","label":"marginal","low":null,"mid":null,"moon_alt":35,"precip":null,"q":0.37,"rh":null,"sky":"night","temp":null,"time":"05:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-17T03:00Z","label":"poor","low":null,"mid":null,"moon_alt":25,"precip":null,"q":0.22,"rh":null,"sky":"astronomical twilight","temp":null,"time":"06:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-09-17T04:00Z","label":"unusable","low":null,"mid":null,"moon_alt":15,"precip":null,"q":0.0,"rh":null,"sky":"civil twilight","temp":null,"time":"07:00","wind":null}],"peak_quality":0.48,"peak_sky":0.48,"quality_hours":3.22,"reasons":["moonlight cost 5.9 quality-hours","daylight and twilight cost 2.5 quality-hours"],"reference_hours":4.0,"score":null,"score_astronomy":39,"score_weather":null,"sky_hours":3.22,"verdict":"unknown","verdict_astronomy":"poor","weather_known":false,"windows":[{"end":"2027-09-16T17:00Z","end_local":"20:00","hours":0.58,"label":"unusable","mean_quality":0.0,"start":"2027-09-16T16:25Z","start_local":"19:25"},{"end":"2027-09-16T18:05Z","end_local":"21:05","hours":1.08,"label":"poor","mean_quality":0.16,"start":"2027-09-16T17:00Z","start_local":"20:00"},{"end":"2027-09-16T21:40Z","end_local":"00:40","hours":3.58,"label":"marginal","mean_quality":0.38,"start":"2027-09-16T18:05Z","start_local":"21:05"},{"end":"2027-09-17T00:10Z","end_local":"03:10","hours":2.5,"label":"poor","mean_quality":0.29,"start":"2027-09-16T21:40Z","start_local":"00:40"},{"end":"2027-09-17T02:30Z","end_local":"05:30","hours":2.33,"label":"marginal","mean_quality":0.34,"start":"2027-09-17T00:10Z","start_local":"03:10"},{"end":"2027-09-17T03:40Z","end_local":"06:40","hours":1.17,"label":"poor","mean_quality":0.14,"start":"2027-09-17T02:30Z","start_local":"05:30"},{"end":"2027-09-17T04:05Z","end_local":"07:05","hours":0.42,"label":"unusable","mean_quality":0.0,"start":"2027-09-17T03:40Z","start_local":"06:40"}]},"calculation_version":"2026-10-10.1","forecast":[],"forecast_source":"none","forecast_updated_at":null,"limits":{"good_alt":30.0,"usable_alt":20.0},"night":{"dark_from":"2027-09-16T18:03:45Z","dark_hours":8.41,"dark_to":"2027-09-17T02:28:28Z","moon":{"illumination":0.99,"phase":"full moon","waxing":false},"moon_free_dark_hours":0.0,"moonrise":"2027-09-16T16:29:49Z","moonset":"2027-09-17T05:22:10Z","sunrise":"2027-09-17T04:02:52Z","sunset":"2027-09-16T16:29:28Z","twilight":{"astronomical":{"end":"2027-09-16T18:03:45Z","start":"2027-09-17T02:28:28Z"},"civil":{"end":"2027-09-16T16:57:18Z","start":"2027-09-17T03:35:00Z"},"nautical":{"end":"2027-09-16T17:30:05Z","start":"2027-09-17T03:02:10Z"}},"window_end":"2027-09-17T09:00:00Z","window_start":"2027-09-16T09:00:00Z"},"night_date":"2027-09-16","site":{"elev_m":1750,"lat":41.693,"lon":24.739,"name":"NAO Rozhen"},"warnings":["No cloud data for this night (beyond the 4-day forecast, or not yet in the archive) \u2014 the score is geometry only."]}