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: 12-22 (89), 12-23 (89), 12-24 (89), 12-25 (89), 12-26 (89) — by astronomy; check the weather when the night is within four days.

2043-12-21astronomy score per night — click a bar for that night2044-01-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2044-01-08 Fri	74	—	unknown	21:05–02:05 (good, 5.0 h)	42.9° 22:45	11.36	58%	61.4°
2044-01-09 Sat	54	—	unknown	19:15–02:30 (marginal, 7.25 h)	42.9° 22:40	11.35	69%	51.0°
2044-01-10 Sun	34	—	unknown	19:35–02:15 (marginal, 6.67 h)	42.9° 22:40	11.33	80%	41.8°
2044-01-11 Mon	20	—	unknown	21:55–01:45 (marginal, 3.83 h)	42.9° 22:35	11.31	88%	35.4°
2044-01-12 Tue	12	—	unknown	—	42.9° 22:30	11.29	95%	33.9°
2044-01-13 Wed	14	—	unknown	19:40–20:15 (marginal, 0.58 h)	42.9° 22:25	11.27	99%	37.9°
2044-01-14 Thu	23	—	unknown	19:05–23:25 (marginal, 4.33 h)	42.9° 22:25	11.25	100%	46.0°
2044-01-15 Fri	37	—	unknown	18:55–01:20 (marginal, 6.42 h)	42.9° 22:20	11.23	98%	56.3°
2044-01-16 Sat	73	—	unknown	19:00–19:30 (good, 0.5 h)	42.9° 22:15	11.21	94%	67.4°
2044-01-17 Sun	86	—	unknown	19:00–23:45 (good, 4.75 h)	42.9° 22:10	11.19	87%	78.8°
2044-01-18 Mon	89	—	unknown	19:00–00:55 (good, 5.92 h)	42.9° 22:05	11.17	79%	90.0°
2044-01-19 Tue	89	—	unknown	19:00–01:05 (good, 6.08 h)	42.9° 22:05	11.14	70%	100.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-12-21&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.