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.

Best nights for Great Orion Nebula: 04-09 (1), 04-10 (1) — by astronomy; check the weather when the night is within four days.

2030-04-09astronomy score per night — click a bar for that night2030-05-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-04-09 Tue	1	—	unknown	—	42.9° 17:45	7.63	38%	30.1°
2030-04-10 Wed	1	—	unknown	—	42.9° 17:40	7.58	48%	35.9°
2030-04-11 Thu	0	—	unknown	—	42.9° 17:40	7.52	58%	44.3°
2030-04-12 Fri	0	—	unknown	—	42.9° 17:35	7.46	68%	54.3°
2030-04-13 Sat	0	—	unknown	—	42.9° 17:30	7.41	77%	65.4°
2030-04-14 Sun	0	—	unknown	—	42.9° 17:25	7.35	86%	77.2°
2030-04-15 Mon	0	—	unknown	—	42.9° 17:25	7.29	93%	89.7°
2030-04-16 Tue	0	—	unknown	—	42.9° 17:20	7.23	98%	102.6°
2030-04-17 Wed	0	—	unknown	—	42.9° 17:15	7.18	100%	115.5°
2030-04-18 Thu	0	—	unknown	—	42.9° 17:10	7.12	99%	128.0°
2030-04-19 Fri	0	—	unknown	—	42.9° 17:05	7.06	95%	139.4°
2030-04-20 Sat	0	—	unknown	—	42.9° 17:05	7.0	89%	148.2°
2030-04-21 Sun	0	—	unknown	—	42.9° 17:00	6.94	80%	152.0°
2030-04-22 Mon	0	—	unknown	—	42.9° 16:55	6.89	70%	149.1°
2030-04-23 Tue	0	—	unknown	—	42.9° 16:50	6.83	59%	141.6°
2030-04-24 Wed	0	—	unknown	—	42.9° 16:45	6.77	48%	131.8°
2030-04-25 Thu	0	—	unknown	—	42.9° 16:45	6.71	38%	121.1°
2030-04-26 Fri	0	—	unknown	—	42.9° 16:40	6.65	28%	110.1°
2030-04-27 Sat	0	—	unknown	—	42.9° 16:35	6.59	20%	99.0°
2030-04-28 Sun	0	—	unknown	—	42.9° 16:30	6.54	12%	88.1°
2030-04-29 Mon	0	—	unknown	—	42.9° 16:30	6.48	7%	77.3°
2030-04-30 Tue	0	—	unknown	—	42.9° 16:25	6.42	3%	66.8°
2030-05-01 Wed	0	—	unknown	—	42.9° 16:20	6.36	0%	56.7°
2030-05-02 Thu	0	—	unknown	—	42.9° 16:15	6.3	0%	47.2°
2030-05-03 Fri	0	—	unknown	—	42.9° 16:10	6.25	2%	38.6°
2030-05-04 Sat	0	—	unknown	—	42.9° 16:10	6.19	5%	31.9°
2030-05-05 Sun	0	—	unknown	—	42.9° 16:05	6.13	10%	28.2°
2030-05-06 Mon	0	—	unknown	—	42.9° 16:00	6.07	16%	28.9°
2030-05-07 Tue	0	—	unknown	—	42.9° 15:55	6.02	24%	33.8°
2030-05-08 Wed	0	—	unknown	—	42.9° 15:50	5.96	32%	41.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-04-09&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.