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.

2041-05-20astronomy score per night — click a bar for that night2041-06-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2041-06-04 Tue	—	unknown	—	42.9° 14:05	4.68	32%	66.9°
2041-06-05 Wed	—	unknown	—	42.9° 14:00	4.65	41%	76.7°
2041-06-06 Thu	—	unknown	—	42.9° 13:55	4.62	50%	86.8°
2041-06-07 Fri	—	unknown	—	42.9° 13:55	4.6	60%	96.9°
2041-06-08 Sat	—	unknown	—	42.9° 13:50	4.57	69%	107.2°
2041-06-09 Sun	—	unknown	—	42.9° 13:45	4.55	78%	117.4°
2041-06-10 Mon	—	unknown	—	42.9° 13:40	4.53	86%	127.3°
2041-06-11 Tue	—	unknown	—	42.9° 13:40	4.51	92%	136.5°
2041-06-12 Wed	—	unknown	—	42.9° 13:35	4.49	97%	144.0°
2041-06-13 Thu	—	unknown	—	42.9° 13:30	4.47	100%	148.0°
2041-06-14 Fri	—	unknown	—	42.9° 13:25	4.46	100%	146.8°
2041-06-15 Sat	—	unknown	—	42.9° 13:20	4.45	97%	140.7°
2041-06-16 Sun	—	unknown	—	42.9° 13:20	4.44	92%	131.4°
2041-06-17 Mon	—	unknown	—	42.9° 13:15	4.43	84%	120.4°
2041-06-18 Tue	—	unknown	—	42.9° 13:10	4.43	74%	108.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-05-20&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.