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: 12-09 (89), 12-22 (89), 12-23 (89), 12-24 (89), 12-25 (89) — by astronomy; check the weather when the night is within four days.

2043-12-09astronomy score per night — click a bar for that night2044-01-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-12-09 Wed	89	—	unknown	21:45–04:05 (good, 6.33 h)	42.9° 00:45	11.44	53%	91.5°
2043-12-10 Thu	88	—	unknown	21:55–04:00 (good, 6.08 h)	42.9° 00:40	11.45	64%	80.3°
2043-12-11 Fri	83	—	unknown	23:20–03:55 (good, 4.58 h)	42.9° 00:35	11.46	74%	68.9°
2043-12-12 Sat	54	—	unknown	21:15–04:25 (marginal, 7.17 h)	42.9° 00:30	11.47	83%	57.7°
2043-12-13 Sun	33	—	unknown	21:40–04:05 (marginal, 6.42 h)	42.9° 00:30	11.48	91%	47.2°
2043-12-14 Mon	18	—	unknown	01:00–03:35 (marginal, 2.58 h)	42.9° 00:25	11.49	97%	38.6°
2043-12-15 Tue	11	—	unknown	—	42.9° 00:20	11.49	100%	34.0°
2043-12-16 Wed	12	—	unknown	—	42.9° 00:15	11.5	99%	35.1°
2043-12-17 Thu	20	—	unknown	21:00–00:30 (marginal, 3.5 h)	42.9° 00:15	11.5	96%	41.3°
2043-12-18 Fri	36	—	unknown	20:35–03:10 (marginal, 6.58 h)	42.9° 00:10	11.5	90%	50.6°
2043-12-19 Sat	56	—	unknown	20:20–03:30 (marginal, 7.17 h)	42.9° 00:05	11.51	82%	61.2°
2043-12-20 Sun	83	—	unknown	20:45–01:40 (good, 4.92 h)	42.9° 00:00	11.51	73%	72.2°
2043-12-21 Mon	87	—	unknown	20:45–02:50 (good, 6.08 h)	42.9° 23:55	11.51	63%	83.2°
2043-12-22 Tue	89	—	unknown	20:40–02:55 (good, 6.25 h)	42.9° 23:55	11.51	53%	94.0°
2043-12-23 Wed	89	—	unknown	20:35–03:00 (good, 6.42 h)	42.9° 23:50	11.51	43%	104.4°
2043-12-24 Thu	89	—	unknown	20:30–03:00 (good, 6.5 h)	42.9° 23:45	11.5	33%	114.3°
2043-12-25 Fri	89	—	unknown	20:25–03:00 (good, 6.58 h)	42.9° 23:40	11.5	25%	123.6°
2043-12-26 Sat	89	—	unknown	20:25–02:55 (good, 6.5 h)	42.9° 23:35	11.5	17%	132.0°
2043-12-27 Sun	89	—	unknown	20:20–02:55 (good, 6.58 h)	42.9° 23:35	11.49	11%	139.1°
2043-12-28 Mon	89	—	unknown	20:15–02:50 (good, 6.58 h)	42.9° 23:30	11.49	6%	144.2°
2043-12-29 Tue	89	—	unknown	20:10–02:45 (good, 6.58 h)	42.9° 23:25	11.48	2%	146.3°
2043-12-30 Wed	89	—	unknown	20:05–02:40 (good, 6.58 h)	42.9° 23:20	11.47	0%	144.8°
2043-12-31 Thu	89	—	unknown	20:05–02:35 (good, 6.5 h)	42.9° 23:20	11.46	0%	140.1°
2044-01-01 Fri	89	—	unknown	20:00–02:35 (good, 6.58 h)	42.9° 23:15	11.45	2%	133.0°
2044-01-02 Sat	89	—	unknown	19:55–02:30 (good, 6.58 h)	42.9° 23:10	11.44	6%	124.4°
2044-01-03 Sun	89	—	unknown	19:55–02:25 (good, 6.5 h)	42.9° 23:05	11.43	11%	114.9°
2044-01-04 Mon	89	—	unknown	19:50–02:20 (good, 6.5 h)	42.9° 23:00	11.42	18%	104.8°
2044-01-05 Tue	89	—	unknown	19:50–02:15 (good, 6.42 h)	42.9° 23:00	11.41	27%	94.2°
2044-01-06 Wed	88	—	unknown	19:55–02:15 (good, 6.33 h)	42.9° 22:55	11.39	37%	83.3°
2044-01-07 Thu	85	—	unknown	20:00–02:10 (good, 6.17 h)	42.9° 22:50	11.38	47%	72.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-12-09&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.