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: 04-07 (3), 04-08 (3), 04-09 (2), 04-10 (1), 04-11 (1) — by astronomy; check the weather when the night is within four days.

2045-04-07astronomy score per night — click a bar for that night2045-05-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-04-07 Fri	3	—	unknown	21:00–21:15 (marginal, 0.25 h)	42.9° 17:55	7.73	63%	145.6°
2045-04-08 Sat	3	—	unknown	21:00–21:10 (marginal, 0.17 h)	42.9° 17:50	7.67	54%	141.3°
2045-04-09 Sun	2	—	unknown	21:00–21:05 (marginal, 0.08 h)	42.9° 17:45	7.61	44%	134.6°
2045-04-10 Mon	1	—	unknown	—	42.9° 17:40	7.56	35%	126.5°
2045-04-11 Tue	1	—	unknown	—	42.9° 17:40	7.5	26%	117.5°
2045-04-12 Wed	1	—	unknown	—	42.9° 17:35	7.44	18%	107.9°
2045-04-13 Thu	1	—	unknown	—	42.9° 17:30	7.39	12%	97.8°
2045-04-14 Fri	1	—	unknown	—	42.9° 17:25	7.33	6%	87.5°
2045-04-15 Sat	0	—	unknown	—	42.9° 17:20	7.27	2%	77.0°
2045-04-16 Sun	0	—	unknown	—	42.9° 17:20	7.21	0%	66.4°
2045-04-17 Mon	0	—	unknown	—	42.9° 17:15	7.15	1%	56.1°
2045-04-18 Tue	0	—	unknown	—	42.9° 17:10	7.1	3%	46.6°
2045-04-19 Wed	0	—	unknown	—	42.9° 17:05	7.04	8%	38.7°
2045-04-20 Thu	0	—	unknown	—	42.9° 17:00	6.98	15%	34.0°
2045-04-21 Fri	0	—	unknown	—	42.9° 17:00	6.92	24%	33.9°
2045-04-22 Sat	0	—	unknown	—	42.9° 16:55	6.86	35%	38.6°
2045-04-23 Sun	0	—	unknown	—	42.9° 16:50	6.81	46%	46.8°
2045-04-24 Mon	0	—	unknown	—	42.9° 16:45	6.75	57%	56.8°
2045-04-25 Tue	0	—	unknown	—	42.9° 16:45	6.69	68%	67.9°
2045-04-26 Wed	0	—	unknown	—	42.9° 16:40	6.63	78%	79.5°
2045-04-27 Thu	0	—	unknown	—	42.9° 16:35	6.57	87%	91.3°
2045-04-28 Fri	0	—	unknown	—	42.9° 16:30	6.51	94%	102.9°
2045-04-29 Sat	0	—	unknown	—	42.9° 16:25	6.46	98%	114.1°
2045-04-30 Sun	0	—	unknown	—	42.9° 16:25	6.4	100%	124.7°
2045-05-01 Mon	0	—	unknown	—	42.9° 16:20	6.34	99%	134.0°
2045-05-02 Tue	0	—	unknown	—	42.9° 16:15	6.28	97%	141.4°
2045-05-03 Wed	0	—	unknown	—	42.9° 16:10	6.22	92%	145.9°
2045-05-04 Thu	0	—	unknown	—	42.9° 16:05	6.17	86%	146.5°
2045-05-05 Fri	0	—	unknown	—	42.9° 16:05	6.11	78%	143.3°
2045-05-06 Sat	0	—	unknown	—	42.9° 16:00	6.05	70%	137.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-04-07&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.