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), 12-10 (89), 12-11 (89), 12-12 (89), 12-13 (89) — by astronomy; check the weather when the night is within four days.

2039-11-30astronomy score per night — click a bar for that night2039-12-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-11-30 Wed	11	—	unknown	—	42.9° 01:20	11.31	100%	30.7°
2039-12-01 Thu	9	—	unknown	—	42.9° 01:15	11.33	99%	29.6°
2039-12-02 Fri	13	—	unknown	—	42.9° 01:10	11.35	96%	32.6°
2039-12-03 Sat	22	—	unknown	21:55–02:20 (marginal, 4.42 h)	42.9° 01:10	11.36	91%	38.8°
2039-12-04 Sun	35	—	unknown	21:30–04:10 (marginal, 6.67 h)	42.9° 01:05	11.38	85%	46.9°
2039-12-05 Mon	52	—	unknown	21:15–04:25 (marginal, 7.17 h)	42.9° 01:00	11.39	77%	56.2°
2039-12-06 Tue	67	—	unknown	22:05–02:00 (good, 3.92 h)	42.9° 00:55	11.41	69%	66.2°
2039-12-07 Wed	84	—	unknown	21:40–03:40 (good, 6.0 h)	42.9° 00:50	11.42	59%	76.7°
2039-12-08 Thu	88	—	unknown	21:35–03:50 (good, 6.25 h)	42.9° 00:50	11.43	49%	87.6°
2039-12-09 Fri	89	—	unknown	21:30–03:55 (good, 6.42 h)	42.9° 00:45	11.44	39%	98.9°
2039-12-10 Sat	89	—	unknown	21:25–03:55 (good, 6.5 h)	42.9° 00:40	11.45	29%	110.5°
2039-12-11 Sun	89	—	unknown	21:20–03:55 (good, 6.58 h)	42.9° 00:35	11.46	19%	122.1°
2039-12-12 Mon	89	—	unknown	21:20–03:50 (good, 6.5 h)	42.9° 00:30	11.47	11%	133.3°
2039-12-13 Tue	89	—	unknown	21:15–03:50 (good, 6.58 h)	42.9° 00:30	11.48	5%	143.1°
2039-12-14 Wed	89	—	unknown	21:10–03:45 (good, 6.58 h)	42.9° 00:25	11.48	1%	149.5°
2039-12-15 Thu	89	—	unknown	21:05–03:40 (good, 6.58 h)	42.9° 00:20	11.49	0%	149.8°
2039-12-16 Fri	89	—	unknown	21:00–03:35 (good, 6.58 h)	42.9° 00:15	11.5	2%	143.6°
2039-12-17 Sat	89	—	unknown	21:00–03:30 (good, 6.5 h)	42.9° 00:15	11.5	8%	133.7°
2039-12-18 Sun	89	—	unknown	20:55–03:30 (good, 6.58 h)	42.9° 00:10	11.5	15%	122.2°
2039-12-19 Mon	89	—	unknown	20:55–03:25 (good, 6.5 h)	42.9° 00:05	11.51	24%	110.2°
2039-12-20 Tue	89	—	unknown	20:55–03:20 (good, 6.42 h)	42.9° 00:00	11.51	34%	98.3°
2039-12-21 Wed	89	—	unknown	20:55–03:15 (good, 6.33 h)	42.9° 23:55	11.51	45%	86.6°
2039-12-22 Thu	88	—	unknown	21:05–03:10 (good, 6.08 h)	42.9° 23:55	11.51	55%	75.4°
2039-12-23 Fri	84	—	unknown	22:05–03:10 (good, 5.08 h)	42.9° 23:50	11.51	65%	64.6°
2039-12-24 Sat	67	—	unknown	01:05–02:30 (good, 1.42 h)	42.9° 23:45	11.5	74%	54.5°
2039-12-25 Sun	41	—	unknown	20:35–03:25 (marginal, 6.83 h)	42.9° 23:40	11.5	82%	45.2°
2039-12-26 Mon	26	—	unknown	21:20–03:05 (marginal, 5.75 h)	42.9° 23:35	11.5	89%	37.3°
2039-12-27 Tue	16	—	unknown	01:20–02:35 (marginal, 1.25 h)	42.9° 23:35	11.49	94%	31.6°
2039-12-28 Wed	10	—	unknown	—	42.9° 23:30	11.49	98%	29.5°
2039-12-29 Thu	10	—	unknown	—	42.9° 23:25	11.48	100%	31.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-11-30&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.