{"assessment":{"best_window":{"end":"2027-04-19T01:55Z","end_local":"04:55","hours":7.08,"label":"marginal","mean_quality":0.42,"start":"2027-04-18T18:50Z","start_local":"21:50"},"cost":{"altitude":0.0,"clouds":0.0,"darkness":2.74,"moon":4.45},"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":"2027-04-18T17:00Z","label":"unusable","low":null,"mid":null,"moon_alt":24,"precip":null,"q":0.0,"rh":null,"sky":"civil twilight","temp":null,"time":"20:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-18T18:00Z","label":"poor","low":null,"mid":null,"moon_alt":32,"precip":null,"q":0.06,"rh":null,"sky":"nautical twilight","temp":null,"time":"21:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-18T19:00Z","label":"marginal","low":null,"mid":null,"moon_alt":39,"precip":null,"q":0.38,"rh":null,"sky":"night","temp":null,"time":"22:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-18T20:00Z","label":"marginal","low":null,"mid":null,"moon_alt":43,"precip":null,"q":0.36,"rh":null,"sky":"night","temp":null,"time":"23:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-18T21:00Z","label":"marginal","low":null,"mid":null,"moon_alt":43,"precip":null,"q":0.36,"rh":null,"sky":"night","temp":null,"time":"00:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-18T22:00Z","label":"marginal","low":null,"mid":null,"moon_alt":40,"precip":null,"q":0.38,"rh":null,"sky":"night","temp":null,"time":"01:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-18T23:00Z","label":"marginal","low":null,"mid":null,"moon_alt":33,"precip":null,"q":0.41,"rh":null,"sky":"night","temp":null,"time":"02:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-19T00:00Z","label":"marginal","low":null,"mid":null,"moon_alt":25,"precip":null,"q":0.46,"rh":null,"sky":"night","temp":null,"time":"03:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-19T01:00Z","label":"marginal","low":null,"mid":null,"moon_alt":15,"precip":null,"q":0.52,"rh":null,"sky":"night","temp":null,"time":"04:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-19T02:00Z","label":"poor","low":null,"mid":null,"moon_alt":4,"precip":null,"q":0.3,"rh":null,"sky":"astronomical twilight","temp":null,"time":"05:00","wind":null},{"alt":null,"cloud":null,"high":null,"iso":"2027-04-19T03:00Z","label":"poor","low":null,"mid":null,"moon_alt":-7,"precip":null,"q":0.15,"rh":null,"sky":"nautical twilight","temp":null,"time":"06:00","wind":null}],"peak_quality":0.58,"peak_sky":0.58,"quality_hours":3.47,"reasons":["moonlight cost 4.5 quality-hours","daylight and twilight cost 2.7 quality-hours"],"reference_hours":4.0,"score":null,"score_astronomy":50,"score_weather":null,"sky_hours":3.47,"verdict":"unknown","verdict_astronomy":"marginal","weather_known":false,"windows":[{"end":"2027-04-18T17:35Z","end_local":"20:35","hours":0.58,"label":"unusable","mean_quality":0.0,"start":"2027-04-18T17:00Z","start_local":"20:00"},{"end":"2027-04-18T18:50Z","end_local":"21:50","hours":1.25,"label":"poor","mean_quality":0.14,"start":"2027-04-18T17:35Z","start_local":"20:35"},{"end":"2027-04-19T01:55Z","end_local":"04:55","hours":7.08,"label":"marginal","mean_quality":0.42,"start":"2027-04-18T18:50Z","start_local":"21:50"},{"end":"2027-04-19T02:10Z","end_local":"05:10","hours":0.25,"label":"poor","mean_quality":0.3,"start":"2027-04-19T01:55Z","start_local":"04:55"},{"end":"2027-04-19T02:35Z","end_local":"05:35","hours":0.42,"label":"marginal","mean_quality":0.38,"start":"2027-04-19T02:10Z","start_local":"05:10"},{"end":"2027-04-19T03:10Z","end_local":"06:10","hours":0.58,"label":"poor","mean_quality":0.15,"start":"2027-04-19T02:35Z","start_local":"05:35"},{"end":"2027-04-19T03:40Z","end_local":"06:40","hours":0.5,"label":"unusable","mean_quality":0.0,"start":"2027-04-19T03:10Z","start_local":"06:10"}]},"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":"2027-04-18T18:46:05Z","dark_hours":7.13,"dark_to":"2027-04-19T01:54:06Z","moon":{"illumination":0.951,"phase":"waxing gibbous","waxing":true},"moon_free_dark_hours":0.0,"moonrise":"2027-04-18T14:41:26Z","moonset":"2027-04-19T02:22:02Z","sunrise":"2027-04-19T03:35:31Z","sunset":"2027-04-18T17:04:36Z","twilight":{"astronomical":{"end":"2027-04-18T18:46:05Z","start":"2027-04-19T01:54:06Z"},"civil":{"end":"2027-04-18T17:33:44Z","start":"2027-04-19T03:06:25Z"},"nautical":{"end":"2027-04-18T18:08:50Z","start":"2027-04-19T02:31:20Z"}},"window_end":"2027-04-19T09:00:00Z","window_start":"2027-04-18T09:00:00Z"},"night_date":"2027-04-18","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."]}