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: 12-20 (89), 12-21 (89), 12-22 (89), 12-23 (89), 12-24 (89) — by astronomy; check the weather when the night is within four days.

2046-12-09astronomy score per night — click a bar for that night2047-01-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2046-12-09 Sun	44	—	unknown	21:35–04:30 (marginal, 6.92 h)	42.9° 00:45	11.44	88%	54.8°
2046-12-10 Mon	29	—	unknown	22:00–04:15 (marginal, 6.25 h)	42.9° 00:40	11.45	94%	45.8°
2046-12-11 Tue	18	—	unknown	01:30–03:45 (marginal, 2.25 h)	42.9° 00:35	11.46	98%	38.2°
2046-12-12 Wed	11	—	unknown	—	42.9° 00:30	11.47	100%	32.9°
2046-12-13 Thu	10	—	unknown	—	42.9° 00:30	11.48	100%	31.5°
2046-12-14 Fri	15	—	unknown	21:35–22:15 (marginal, 0.67 h)	42.9° 00:25	11.49	98%	34.7°
2046-12-15 Sat	25	—	unknown	20:55–02:10 (marginal, 5.25 h)	42.9° 00:20	11.49	93%	41.6°
2046-12-16 Sun	42	—	unknown	20:35–03:25 (marginal, 6.83 h)	42.9° 00:15	11.5	87%	50.9°
2046-12-17 Mon	72	—	unknown	21:30–23:40 (good, 2.17 h)	42.9° 00:10	11.5	78%	61.5°
2046-12-18 Tue	85	—	unknown	20:55–02:20 (good, 5.42 h)	42.9° 00:10	11.5	69%	72.9°
2046-12-19 Wed	88	—	unknown	20:50–03:00 (good, 6.17 h)	42.9° 00:05	11.51	58%	84.7°
2046-12-20 Thu	89	—	unknown	20:45–03:10 (good, 6.42 h)	42.9° 00:00	11.51	46%	96.7°
2046-12-21 Fri	89	—	unknown	20:40–03:10 (good, 6.5 h)	42.9° 23:55	11.51	35%	108.7°
2046-12-22 Sat	89	—	unknown	20:40–03:10 (good, 6.5 h)	42.9° 23:50	11.51	25%	120.4°
2046-12-23 Sun	89	—	unknown	20:35–03:05 (good, 6.5 h)	42.9° 23:50	11.51	15%	131.3°
2046-12-24 Mon	89	—	unknown	20:30–03:05 (good, 6.58 h)	42.9° 23:45	11.5	8%	140.6°
2046-12-25 Tue	89	—	unknown	20:25–03:00 (good, 6.58 h)	42.9° 23:40	11.5	3%	147.0°
2046-12-26 Wed	89	—	unknown	20:20–02:55 (good, 6.58 h)	42.9° 23:35	11.5	0%	148.5°
2046-12-27 Thu	89	—	unknown	20:20–02:50 (good, 6.5 h)	42.9° 23:35	11.49	0%	144.8°
2046-12-28 Fri	89	—	unknown	20:15–02:50 (good, 6.58 h)	42.9° 23:30	11.48	3%	137.5°
2046-12-29 Sat	89	—	unknown	20:10–02:45 (good, 6.58 h)	42.9° 23:25	11.48	7%	128.3°
2046-12-30 Sun	89	—	unknown	20:10–02:40 (good, 6.5 h)	42.9° 23:20	11.47	13%	118.4°
2046-12-31 Mon	89	—	unknown	20:05–02:35 (good, 6.5 h)	42.9° 23:15	11.46	20%	108.1°
2047-01-01 Tue	89	—	unknown	20:05–02:30 (good, 6.42 h)	42.9° 23:15	11.45	29%	97.8°
2047-01-02 Wed	89	—	unknown	20:05–02:30 (good, 6.42 h)	42.9° 23:10	11.44	38%	87.6°
2047-01-03 Thu	86	—	unknown	20:15–02:25 (good, 6.17 h)	42.9° 23:05	11.43	47%	77.5°
2047-01-04 Fri	82	—	unknown	20:40–02:20 (good, 5.67 h)	42.9° 23:00	11.42	57%	67.6°
2047-01-05 Sat	63	—	unknown	22:45–01:50 (good, 3.08 h)	42.9° 22:55	11.4	66%	58.0°
2047-01-06 Sun	47	—	unknown	19:35–02:40 (marginal, 7.08 h)	42.9° 22:55	11.39	75%	48.9°
2047-01-07 Mon	31	—	unknown	19:55–02:25 (marginal, 6.5 h)	42.9° 22:50	11.37	83%	40.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2046-12-09&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.