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: 12-08 (89), 12-09 (89), 12-10 (89), 12-25 (89), 12-26 (89) — by astronomy; check the weather when the night is within four days.

2040-12-08astronomy score per night — click a bar for that night2041-01-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-12-08 Sat	89	—	unknown	21:30–04:05 (good, 6.58 h)	42.9° 00:45	11.44	27%	115.3°
2040-12-09 Sun	89	—	unknown	21:35–04:00 (good, 6.42 h)	42.9° 00:40	11.45	38%	103.3°
2040-12-10 Mon	89	—	unknown	21:35–03:55 (good, 6.33 h)	42.9° 00:35	11.46	49%	91.4°
2040-12-11 Tue	88	—	unknown	21:45–03:50 (good, 6.08 h)	42.9° 00:35	11.47	60%	79.6°
2040-12-12 Wed	85	—	unknown	22:50–03:50 (good, 5.0 h)	42.9° 00:30	11.48	71%	68.2°
2040-12-13 Thu	73	—	unknown	02:00–03:10 (good, 1.17 h)	42.9° 00:25	11.48	80%	57.5°
2040-12-14 Fri	39	—	unknown	21:20–04:05 (marginal, 6.75 h)	42.9° 00:20	11.49	88%	47.6°
2040-12-15 Sat	25	—	unknown	23:00–03:45 (marginal, 4.75 h)	42.9° 00:20	11.49	94%	39.2°
2040-12-16 Sun	14	—	unknown	02:30–03:05 (marginal, 0.58 h)	42.9° 00:15	11.5	98%	33.3°
2040-12-17 Mon	10	—	unknown	—	42.9° 00:10	11.5	100%	31.1°
2040-12-18 Tue	11	—	unknown	—	42.9° 00:05	11.51	100%	33.1°
2040-12-19 Wed	17	—	unknown	21:05–22:50 (marginal, 1.75 h)	42.9° 00:00	11.51	98%	38.6°
2040-12-20 Thu	27	—	unknown	20:30–02:25 (marginal, 5.92 h)	42.9° 00:00	11.51	94%	46.2°
2040-12-21 Fri	41	—	unknown	20:15–03:05 (marginal, 6.83 h)	42.9° 23:55	11.51	89%	55.1°
2040-12-22 Sat	59	—	unknown	21:30–22:05 (good, 0.58 h)	42.9° 23:50	11.51	83%	64.5°
2040-12-23 Sun	82	—	unknown	20:30–01:20 (good, 4.83 h)	42.9° 23:45	11.5	75%	74.4°
2040-12-24 Mon	87	—	unknown	20:30–02:30 (good, 6.0 h)	42.9° 23:40	11.5	67%	84.5°
2040-12-25 Tue	89	—	unknown	20:25–02:40 (good, 6.25 h)	42.9° 23:40	11.5	58%	94.8°
2040-12-26 Wed	89	—	unknown	20:20–02:45 (good, 6.42 h)	42.9° 23:35	11.49	48%	105.2°
2040-12-27 Thu	89	—	unknown	20:15–02:45 (good, 6.5 h)	42.9° 23:30	11.49	38%	115.6°
2040-12-28 Fri	89	—	unknown	20:10–02:45 (good, 6.58 h)	42.9° 23:25	11.48	28%	125.9°
2040-12-29 Sat	89	—	unknown	20:10–02:40 (good, 6.5 h)	42.9° 23:25	11.47	19%	135.7°
2040-12-30 Sun	89	—	unknown	20:05–02:40 (good, 6.58 h)	42.9° 23:20	11.47	11%	143.8°
2040-12-31 Mon	89	—	unknown	20:00–02:35 (good, 6.58 h)	42.9° 23:15	11.46	5%	148.5°
2041-01-01 Tue	89	—	unknown	19:55–02:30 (good, 6.58 h)	42.9° 23:10	11.45	1%	147.6°
2041-01-02 Wed	89	—	unknown	19:55–02:25 (good, 6.5 h)	42.9° 23:05	11.44	0%	141.2°
2041-01-03 Thu	89	—	unknown	19:50–02:20 (good, 6.5 h)	42.9° 23:05	11.42	2%	131.2°
2041-01-04 Fri	89	—	unknown	19:45–02:20 (good, 6.58 h)	42.9° 23:00	11.41	7%	119.6°
2041-01-05 Sat	89	—	unknown	19:45–02:15 (good, 6.5 h)	42.9° 22:55	11.4	14%	107.3°
2041-01-06 Sun	89	—	unknown	19:40–02:10 (good, 6.5 h)	42.9° 22:50	11.38	24%	94.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-08&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.