{"assessment":{"best_window":{"end":"2027-05-20T01:00Z","end_local":"04:00","hours":5.33,"label":"marginal","mean_quality":0.46,"start":"2027-05-19T19:40Z","start_local":"22:40"},"cost":{"altitude":0.0,"clouds":0.0,"darkness":3.11,"moon":3.32},"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":"2027-05-19T18:00Z","label":"unusable","low":null,"mid":null,"moon_alt":7,"precip":null,"q":0.0,"rh":null,"sky":"civil twilight","temp":null,"time":"21:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-05-19T19:00Z","label":"poor","low":null,"mid":null,"moon_alt":15,"precip":null,"q":0.25,"rh":null,"sky":"astronomical twilight","temp":null,"time":"22:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-05-19T20:00Z","label":"marginal","low":null,"mid":null,"moon_alt":20,"precip":null,"q":0.46,"rh":null,"sky":"night","temp":null,"time":"23:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-05-19T21:00Z","label":"marginal","low":null,"mid":null,"moon_alt":24,"precip":null,"q":0.44,"rh":null,"sky":"night","temp":null,"time":"00:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-05-19T22:00Z","label":"marginal","low":null,"mid":null,"moon_alt":24,"precip":null,"q":0.44,"rh":null,"sky":"night","temp":null,"time":"01:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-05-19T23:00Z","label":"marginal","low":null,"mid":null,"moon_alt":22,"precip":null,"q":0.45,"rh":null,"sky":"night","temp":null,"time":"02:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-05-20T00:00Z","label":"marginal","low":null,"mid":null,"moon_alt":17,"precip":null,"q":0.48,"rh":null,"sky":"night","temp":null,"time":"03:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-05-20T01:00Z","label":"poor","low":null,"mid":null,"moon_alt":11,"precip":null,"q":0.26,"rh":null,"sky":"astronomical twilight","temp":null,"time":"04:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-05-20T02:00Z","label":"poor","low":null,"mid":null,"moon_alt":2,"precip":null,"q":0.09,"rh":null,"sky":"nautical twilight","temp":null,"time":"05:00","wind":null}],"peak_quality":0.52,"peak_sky":0.52,"quality_hours":2.98,"reasons":["moonlight cost 3.3 quality-hours","daylight and twilight cost 3.1 quality-hours"],"reference_hours":4.0,"score":null,"score_astronomy":39,"score_weather":null,"sky_hours":2.98,"verdict":"unknown","verdict_astronomy":"poor","weather_known":false,"windows":[{"end":"2027-05-19T18:10Z","end_local":"21:10","hours":0.58,"label":"unusable","mean_quality":0.0,"start":"2027-05-19T17:35Z","start_local":"20:35"},{"end":"2027-05-19T19:40Z","end_local":"22:40","hours":1.5,"label":"poor","mean_quality":0.16,"start":"2027-05-19T18:10Z","start_local":"21:10"},{"end":"2027-05-20T01:00Z","end_local":"04:00","hours":5.33,"label":"marginal","mean_quality":0.46,"start":"2027-05-19T19:40Z","start_local":"22:40"},{"end":"2027-05-20T02:30Z","end_local":"05:30","hours":1.5,"label":"poor","mean_quality":0.19,"start":"2027-05-20T01:00Z","start_local":"04:00"},{"end":"2027-05-20T03:00Z","end_local":"06:00","hours":0.5,"label":"unusable","mean_quality":0.0,"start":"2027-05-20T02:30Z","start_local":"05:30"}]},"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":"2027-05-19T19:35:56Z","dark_hours":5.38,"dark_to":"2027-05-20T00:58:50Z","moon":{"illumination":0.995,"phase":"full moon","waxing":true},"moon_free_dark_hours":0.0,"moonrise":"2027-05-19T17:09:11Z","moonset":"2027-05-20T02:15:48Z","sunrise":"2027-05-20T02:57:14Z","sunset":"2027-05-19T17:37:31Z","twilight":{"astronomical":{"end":"2027-05-19T19:35:56Z","start":"2027-05-20T00:58:50Z"},"civil":{"end":"2027-05-19T18:09:43Z","start":"2027-05-20T02:25:03Z"},"nautical":{"end":"2027-05-19T18:50:04Z","start":"2027-05-20T01:44:42Z"}},"window_end":"2027-05-20T09:00:00Z","window_start":"2027-05-19T09:00:00Z"},"night_date":"2027-05-19","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."]}