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: 12-15 (89), 12-16 (89), 12-17 (89), 12-18 (89), 12-19 (89) — by astronomy; check the weather when the night is within four days.

2041-12-02astronomy score per night — click a bar for that night2041-12-31

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-12-02 Mon	87	—	unknown	22:55–04:30 (good, 5.58 h)	42.9° 01:10	11.35	73%	75.1°
2041-12-03 Tue	82	—	unknown	01:20–04:25 (good, 3.08 h)	42.9° 01:05	11.37	83%	63.5°
2041-12-04 Wed	43	—	unknown	21:55–04:50 (marginal, 6.92 h)	42.9° 01:00	11.38	90%	52.5°
2041-12-05 Thu	26	—	unknown	23:20–04:30 (marginal, 5.17 h)	42.9° 01:00	11.4	96%	42.9°
2041-12-06 Fri	15	—	unknown	02:50–03:50 (marginal, 1.0 h)	42.9° 00:55	11.41	99%	35.7°
2041-12-07 Sat	10	—	unknown	—	42.9° 00:50	11.42	100%	32.5°
2041-12-08 Sun	12	—	unknown	—	42.9° 00:45	11.44	98%	34.1°
2041-12-09 Mon	19	—	unknown	21:35–00:45 (marginal, 3.17 h)	42.9° 00:40	11.45	94%	39.6°
2041-12-10 Tue	32	—	unknown	21:05–03:35 (marginal, 6.5 h)	42.9° 00:40	11.46	89%	47.6°
2041-12-11 Wed	48	—	unknown	20:50–03:55 (marginal, 7.08 h)	42.9° 00:35	11.47	82%	56.6°
2041-12-12 Thu	67	—	unknown	21:40–01:00 (good, 3.33 h)	42.9° 00:30	11.47	74%	66.3°
2041-12-13 Fri	84	—	unknown	21:10–02:55 (good, 5.75 h)	42.9° 00:25	11.48	65%	76.1°
2041-12-14 Sat	88	—	unknown	21:10–03:20 (good, 6.17 h)	42.9° 00:25	11.49	56%	86.1°
2041-12-15 Sun	89	—	unknown	21:05–03:25 (good, 6.33 h)	42.9° 00:20	11.49	47%	96.1°
2041-12-16 Mon	89	—	unknown	21:00–03:25 (good, 6.42 h)	42.9° 00:15	11.5	37%	106.0°
2041-12-17 Tue	89	—	unknown	20:55–03:25 (good, 6.5 h)	42.9° 00:10	11.5	28%	115.9°
2041-12-18 Wed	89	—	unknown	20:55–03:25 (good, 6.5 h)	42.9° 00:05	11.5	20%	125.4°
2041-12-19 Thu	89	—	unknown	20:50–03:20 (good, 6.5 h)	42.9° 00:05	11.51	13%	134.3°
2041-12-20 Fri	89	—	unknown	20:45–03:20 (good, 6.58 h)	42.9° 00:00	11.51	7%	141.9°
2041-12-21 Sat	89	—	unknown	20:40–03:15 (good, 6.58 h)	42.9° 23:55	11.51	2%	146.7°
2041-12-22 Sun	89	—	unknown	20:35–03:10 (good, 6.58 h)	42.9° 23:50	11.51	0%	147.2°
2041-12-23 Mon	89	—	unknown	20:35–03:05 (good, 6.5 h)	42.9° 23:45	11.51	1%	142.9°
2041-12-24 Tue	89	—	unknown	20:30–03:00 (good, 6.5 h)	42.9° 23:45	11.5	3%	134.9°
2041-12-25 Wed	89	—	unknown	20:25–03:00 (good, 6.58 h)	42.9° 23:40	11.5	9%	124.8°
2041-12-26 Thu	89	—	unknown	20:20–02:55 (good, 6.58 h)	42.9° 23:35	11.49	16%	113.5°
2041-12-27 Fri	89	—	unknown	20:20–02:50 (good, 6.5 h)	42.9° 23:30	11.49	26%	101.7°
2041-12-28 Sat	89	—	unknown	20:25–02:45 (good, 6.33 h)	42.9° 23:25	11.48	36%	89.7°
2041-12-29 Sun	88	—	unknown	20:30–02:45 (good, 6.25 h)	42.9° 23:25	11.48	48%	77.7°
2041-12-30 Mon	84	—	unknown	21:00–02:40 (good, 5.67 h)	42.9° 23:20	11.47	59%	66.2°
2041-12-31 Tue	62	—	unknown	23:50–02:05 (good, 2.25 h)	42.9° 23:15	11.46	70%	55.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-12-02&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.