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: 12-29 (89), 12-30 (89), 12-31 (89), 01-01 (89), 01-02 (89) — by astronomy; check the weather when the night is within four days.

2045-12-25astronomy score per night — click a bar for that night2046-01-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-12-25 Mon	29	—	unknown	20:10–02:15 (marginal, 6.08 h)	42.9° 23:40	11.5	95%	46.4°
2045-12-26 Tue	48	—	unknown	19:50–02:50 (marginal, 7.0 h)	42.9° 23:35	11.49	89%	57.0°
2045-12-27 Wed	82	—	unknown	20:15–00:10 (good, 3.92 h)	42.9° 23:30	11.49	80%	68.6°
2045-12-28 Thu	87	—	unknown	20:15–02:15 (good, 6.0 h)	42.9° 23:30	11.48	70%	80.6°
2045-12-29 Fri	89	—	unknown	20:10–02:25 (good, 6.25 h)	42.9° 23:25	11.48	59%	92.5°
2045-12-30 Sat	89	—	unknown	20:05–02:30 (good, 6.42 h)	42.9° 23:20	11.47	48%	104.3°
2045-12-31 Sun	89	—	unknown	20:00–02:30 (good, 6.5 h)	42.9° 23:15	11.46	37%	115.5°
2046-01-01 Mon	89	—	unknown	20:00–02:30 (good, 6.5 h)	42.9° 23:10	11.45	27%	126.0°
2046-01-02 Tue	89	—	unknown	19:55–02:25 (good, 6.5 h)	42.9° 23:10	11.44	18%	135.3°
2046-01-03 Wed	89	—	unknown	19:50–02:25 (good, 6.58 h)	42.9° 23:05	11.43	11%	142.6°
2046-01-04 Thu	89	—	unknown	19:45–02:20 (good, 6.58 h)	42.9° 23:00	11.41	5%	146.8°
2046-01-05 Fri	89	—	unknown	19:40–02:15 (good, 6.58 h)	42.9° 22:55	11.4	2%	146.8°
2046-01-06 Sat	89	—	unknown	19:40–02:10 (good, 6.5 h)	42.9° 22:50	11.39	0%	142.8°
2046-01-07 Sun	89	—	unknown	19:35–02:05 (good, 6.5 h)	42.9° 22:50	11.37	1%	136.1°
2046-01-08 Mon	89	—	unknown	19:30–02:05 (good, 6.58 h)	42.9° 22:45	11.36	3%	127.8°
2046-01-09 Tue	89	—	unknown	19:25–02:00 (good, 6.58 h)	42.9° 22:40	11.34	7%	118.6°
2046-01-10 Wed	89	—	unknown	19:25–01:55 (good, 6.5 h)	42.9° 22:35	11.32	12%	109.0°
2046-01-11 Thu	89	—	unknown	19:20–01:50 (good, 6.5 h)	42.9° 22:35	11.3	19%	99.2°
2046-01-12 Fri	89	—	unknown	19:25–01:50 (good, 6.42 h)	42.9° 22:30	11.28	27%	89.3°
2046-01-13 Sat	87	—	unknown	19:25–01:45 (good, 6.33 h)	42.9° 22:25	11.26	36%	79.3°
2046-01-14 Sun	83	—	unknown	19:35–01:40 (good, 6.08 h)	42.9° 22:20	11.24	45%	69.4°
2046-01-15 Mon	68	—	unknown	20:30–01:15 (good, 4.75 h)	42.9° 22:15	11.22	55%	59.6°
2046-01-16 Tue	55	—	unknown	18:55–02:05 (marginal, 7.17 h)	42.9° 22:15	11.2	65%	50.2°
2046-01-17 Wed	37	—	unknown	19:00–01:50 (marginal, 6.83 h)	42.9° 22:10	11.18	75%	41.7°
2046-01-18 Thu	22	—	unknown	19:15–01:25 (marginal, 6.17 h)	42.9° 22:05	11.15	83%	35.3°
2046-01-19 Fri	14	—	unknown	—	42.9° 22:00	11.13	91%	32.7°
2046-01-20 Sat	13	—	unknown	19:15–19:30 (marginal, 0.25 h)	42.9° 21:55	11.1	96%	35.3°
2046-01-21 Sun	19	—	unknown	19:00–22:05 (marginal, 3.08 h)	42.9° 21:55	11.08	100%	42.4°
2046-01-22 Mon	31	—	unknown	19:05–00:40 (marginal, 5.58 h)	42.9° 21:50	11.05	100%	52.5°
2046-01-23 Tue	48	—	unknown	19:05–01:05 (marginal, 6.0 h)	42.9° 21:45	11.02	97%	64.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-12-25&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.