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: 12-13 (89), 12-14 (89), 12-15 (89), 12-29 (89), 12-30 (89) — by astronomy; check the weather when the night is within four days.

2045-12-13astronomy score per night — click a bar for that night2046-01-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-12-13 Wed	89	—	unknown	21:15–03:45 (good, 6.5 h)	42.9° 00:25	11.48	26%	115.6°
2045-12-14 Thu	89	—	unknown	21:15–03:40 (good, 6.42 h)	42.9° 00:25	11.49	35%	105.9°
2045-12-15 Fri	89	—	unknown	21:15–03:40 (good, 6.42 h)	42.9° 00:20	11.49	44%	96.1°
2045-12-16 Sat	88	—	unknown	21:20–03:35 (good, 6.25 h)	42.9° 00:15	11.5	54%	86.0°
2045-12-17 Sun	86	—	unknown	21:30–03:30 (good, 6.0 h)	42.9° 00:10	11.5	63%	75.9°
2045-12-18 Mon	80	—	unknown	23:15–03:25 (good, 4.17 h)	42.9° 00:05	11.5	72%	65.9°
2045-12-19 Tue	51	—	unknown	20:45–03:55 (marginal, 7.17 h)	42.9° 00:05	11.51	81%	55.9°
2045-12-20 Wed	34	—	unknown	21:05–03:35 (marginal, 6.5 h)	42.9° 00:00	11.51	88%	46.6°
2045-12-21 Thu	20	—	unknown	23:55–03:10 (marginal, 3.25 h)	42.9° 23:55	11.51	94%	38.6°
2045-12-22 Fri	11	—	unknown	—	42.9° 23:50	11.51	98%	33.5°
2045-12-23 Sat	10	—	unknown	—	42.9° 23:45	11.5	100%	33.1°
2045-12-24 Sun	16	—	unknown	20:45–22:20 (marginal, 1.58 h)	42.9° 23:45	11.5	99%	37.9°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-12-13&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.