{"assessment":{"best_window":{"end":"2027-06-21T20:35Z","end_local":"23:35","hours":0.33,"label":"good","mean_quality":0.61,"start":"2027-06-21T20:15Z","start_local":"23:15"},"cost":{"altitude":0.0,"clouds":0.0,"darkness":3.4,"moon":2.45},"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 possible, with compromises \u2014 weather unknown","hourly":[{"alt":null,"cloud":null,"high":null,"iso":"2027-06-21T18:00Z","label":"unusable","low":null,"mid":null,"moon_alt":-21,"precip":null,"q":0.0,"rh":null,"sky":"civil twilight","temp":null,"time":"21:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-06-21T19:00Z","label":"poor","low":null,"mid":null,"moon_alt":-10,"precip":null,"q":0.15,"rh":null,"sky":"nautical twilight","temp":null,"time":"22:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-06-21T20:00Z","label":"marginal","low":null,"mid":null,"moon_alt":0,"precip":null,"q":0.5,"rh":null,"sky":"astronomical twilight","temp":null,"time":"23:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-06-21T21:00Z","label":"marginal","low":null,"mid":null,"moon_alt":9,"precip":null,"q":0.57,"rh":null,"sky":"night","temp":null,"time":"00:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-06-21T22:00Z","label":"marginal","low":null,"mid":null,"moon_alt":17,"precip":null,"q":0.52,"rh":null,"sky":"night","temp":null,"time":"01:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-06-21T23:00Z","label":"marginal","low":null,"mid":null,"moon_alt":23,"precip":null,"q":0.49,"rh":null,"sky":"night","temp":null,"time":"02:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-06-22T00:00Z","label":"marginal","low":null,"mid":null,"moon_alt":26,"precip":null,"q":0.47,"rh":null,"sky":"night","temp":null,"time":"03:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-06-22T01:00Z","label":"poor","low":null,"mid":null,"moon_alt":27,"precip":null,"q":0.23,"rh":null,"sky":"astronomical twilight","temp":null,"time":"04:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-06-22T02:00Z","label":"poor","low":null,"mid":null,"moon_alt":25,"precip":null,"q":0.07,"rh":null,"sky":"nautical twilight","temp":null,"time":"05:00","wind":null}],"peak_quality":0.62,"peak_sky":0.62,"quality_hours":3.07,"reasons":["daylight and twilight cost 3.4 quality-hours","moonlight cost 2.4 quality-hours"],"reference_hours":4.0,"score":null,"score_astronomy":47,"score_weather":null,"sky_hours":3.07,"verdict":"unknown","verdict_astronomy":"marginal","weather_known":false,"windows":[{"end":"2027-06-21T18:35Z","end_local":"21:35","hours":0.67,"label":"unusable","mean_quality":0.0,"start":"2027-06-21T17:55Z","start_local":"20:55"},{"end":"2027-06-21T19:20Z","end_local":"22:20","hours":0.75,"label":"poor","mean_quality":0.15,"start":"2027-06-21T18:35Z","start_local":"21:35"},{"end":"2027-06-21T20:15Z","end_local":"23:15","hours":0.92,"label":"marginal","mean_quality":0.47,"start":"2027-06-21T19:20Z","start_local":"22:20"},{"end":"2027-06-21T20:35Z","end_local":"23:35","hours":0.33,"label":"good","mean_quality":0.61,"start":"2027-06-21T20:15Z","start_local":"23:15"},{"end":"2027-06-22T00:40Z","end_local":"03:40","hours":4.08,"label":"marginal","mean_quality":0.51,"start":"2027-06-21T20:35Z","start_local":"23:35"},{"end":"2027-06-22T02:15Z","end_local":"05:15","hours":1.58,"label":"poor","mean_quality":0.15,"start":"2027-06-22T00:40Z","start_local":"03:40"},{"end":"2027-06-22T02:50Z","end_local":"05:50","hours":0.58,"label":"unusable","mean_quality":0.0,"start":"2027-06-22T02:15Z","start_local":"05:15"}]},"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":"2027-06-21T20:10:17Z","dark_hours":4.42,"dark_to":"2027-06-22T00:35:34Z","moon":{"illumination":0.925,"phase":"waning gibbous","waxing":false},"moon_free_dark_hours":0.0,"moonrise":"2027-06-21T20:01:46Z","moonset":"2027-06-22T05:33:24Z","sunrise":"2027-06-22T02:46:48Z","sunset":"2027-06-21T17:59:02Z","twilight":{"astronomical":{"end":"2027-06-21T20:10:17Z","start":"2027-06-22T00:35:34Z"},"civil":{"end":"2027-06-21T18:33:16Z","start":"2027-06-22T02:12:34Z"},"nautical":{"end":"2027-06-21T19:17:18Z","start":"2027-06-22T01:28:33Z"}},"window_end":"2027-06-22T09:00:00Z","window_start":"2027-06-21T09:00:00Z"},"night_date":"2027-06-21","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."]}