Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

2041-05-05astronomy score per night — click a bar for that night2041-06-03

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-05-05 Sun	—	unknown	—	42.9° 16:05	6.11	29%	43.0°
2041-05-06 Mon	—	unknown	—	42.9° 16:00	6.05	38%	51.4°
2041-05-07 Tue	—	unknown	—	42.9° 15:55	6.0	48%	60.5°
2041-05-08 Wed	—	unknown	—	42.9° 15:50	5.94	57%	70.2°
2041-05-09 Thu	—	unknown	—	42.9° 15:50	5.89	66%	80.1°
2041-05-10 Fri	—	unknown	—	42.9° 15:45	5.83	75%	90.3°
2041-05-11 Sat	—	unknown	—	42.9° 15:40	5.77	83%	100.5°
2041-05-12 Sun	—	unknown	—	42.9° 15:35	5.72	90%	110.9°
2041-05-13 Mon	—	unknown	—	42.9° 15:30	5.67	95%	121.1°
2041-05-14 Tue	—	unknown	—	42.9° 15:30	5.61	99%	130.9°
2041-05-15 Wed	—	unknown	—	42.9° 15:25	5.56	100%	139.6°
2041-05-16 Thu	—	unknown	—	42.9° 15:20	5.51	99%	145.9°
2041-05-17 Fri	—	unknown	—	42.9° 15:15	5.45	96%	148.2°
2041-05-18 Sat	—	unknown	—	42.9° 15:10	5.4	90%	145.2°
2041-05-19 Sun	—	unknown	—	42.9° 15:10	5.35	82%	138.1°
2041-05-20 Mon	—	unknown	—	42.9° 15:05	5.3	72%	128.4°
2041-05-21 Tue	—	unknown	—	42.9° 15:00	5.25	62%	117.3°
2041-05-22 Wed	—	unknown	—	42.9° 14:55	5.2	50%	105.6°
2041-05-23 Thu	—	unknown	—	42.9° 14:50	5.16	39%	93.7°
2041-05-24 Fri	—	unknown	—	42.9° 14:50	5.11	28%	81.7°
2041-05-25 Sat	—	unknown	—	42.9° 14:45	5.07	18%	70.0°
2041-05-26 Sun	—	unknown	—	42.9° 14:40	5.02	10%	58.7°
2041-05-27 Mon	—	unknown	—	42.9° 14:35	4.98	5%	48.4°
2041-05-28 Tue	—	unknown	—	42.9° 14:35	4.94	1%	39.7°
2041-05-29 Wed	—	unknown	—	42.9° 14:30	4.9	0%	33.7°
2041-05-30 Thu	—	unknown	—	42.9° 14:25	4.86	1%	31.8°
2041-05-31 Fri	—	unknown	—	42.9° 14:20	4.82	4%	34.4°
2041-06-01 Sat	—	unknown	—	42.9° 14:15	4.78	9%	40.4°
2041-06-02 Sun	—	unknown	—	42.9° 14:15	4.75	16%	48.4°
2041-06-03 Mon	—	unknown	—	42.9° 14:10	4.71	23%	57.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-05-05&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.