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.

2030-05-21astronomy score per night — click a bar for that night2030-06-19

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-05-21 Tue	—	unknown	—	42.9° 15:00	5.27	74%	135.1°
2030-05-22 Wed	—	unknown	—	42.9° 14:55	5.22	64%	124.3°
2030-05-23 Thu	—	unknown	—	42.9° 14:55	5.17	53%	113.0°
2030-05-24 Fri	—	unknown	—	42.9° 14:50	5.13	43%	101.8°
2030-05-25 Sat	—	unknown	—	42.9° 14:45	5.08	33%	90.8°
2030-05-26 Sun	—	unknown	—	42.9° 14:40	5.04	24%	79.9°
2030-05-27 Mon	—	unknown	—	42.9° 14:40	4.99	16%	69.3°
2030-05-28 Tue	—	unknown	—	42.9° 14:35	4.95	10%	59.1°
2030-05-29 Wed	—	unknown	—	42.9° 14:30	4.91	5%	49.5°
2030-05-30 Thu	—	unknown	—	42.9° 14:25	4.87	2%	40.6°
2030-05-31 Fri	—	unknown	—	42.9° 14:20	4.83	0%	33.3°
2030-06-01 Sat	—	unknown	—	42.9° 14:20	4.79	0%	28.7°
2030-06-02 Sun	—	unknown	—	42.9° 14:15	4.76	2%	28.3°
2030-06-03 Mon	—	unknown	—	42.9° 14:10	4.73	6%	32.2°
2030-06-04 Tue	—	unknown	—	42.9° 14:05	4.69	12%	39.3°
2030-06-05 Wed	—	unknown	—	42.9° 14:00	4.66	19%	48.4°
2030-06-06 Thu	—	unknown	—	42.9° 14:00	4.63	28%	58.5°
2030-06-07 Fri	—	unknown	—	42.9° 13:55	4.61	37%	69.4°
2030-06-08 Sat	—	unknown	—	42.9° 13:50	4.58	48%	80.9°
2030-06-09 Sun	—	unknown	—	42.9° 13:45	4.56	58%	92.7°
2030-06-10 Mon	—	unknown	—	42.9° 13:40	4.53	69%	105.0°
2030-06-11 Tue	—	unknown	—	42.9° 13:40	4.51	79%	117.3°
2030-06-12 Wed	—	unknown	—	42.9° 13:35	4.5	88%	129.4°
2030-06-13 Thu	—	unknown	—	42.9° 13:30	4.48	95%	140.6°
2030-06-14 Fri	—	unknown	—	42.9° 13:25	4.46	99%	149.1°
2030-06-15 Sat	—	unknown	—	42.9° 13:25	4.45	100%	152.0°
2030-06-16 Sun	—	unknown	—	42.9° 13:20	4.44	98%	148.0°
2030-06-17 Mon	—	unknown	—	42.9° 13:15	4.43	93%	139.2°
2030-06-18 Tue	—	unknown	—	42.9° 13:10	4.43	86%	128.4°
2030-06-19 Wed	—	unknown	—	42.9° 13:05	4.42	78%	116.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-05-21&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.