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: 12-25 (89), 12-26 (89), 12-27 (89), 12-28 (89), 01-11 (89) — by astronomy; check the weather when the night is within four days.

2041-12-25astronomy score per night — click a bar for that night2042-01-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2042-01-01 Wed	41	—	unknown	20:00–02:55 (marginal, 6.92 h)	42.9° 23:10	11.45	79%	45.4°
2042-01-02 Thu	25	—	unknown	20:30–02:35 (marginal, 6.08 h)	42.9° 23:10	11.44	87%	37.6°
2042-01-03 Fri	15	—	unknown	01:30–01:55 (marginal, 0.42 h)	42.9° 23:05	11.43	94%	33.0°
2042-01-04 Sat	11	—	unknown	—	42.9° 23:00	11.41	98%	33.0°
2042-01-05 Sun	14	—	unknown	20:15–20:20 (marginal, 0.08 h)	42.9° 22:55	11.4	100%	37.3°
2042-01-06 Mon	21	—	unknown	19:35–23:25 (marginal, 3.83 h)	42.9° 22:50	11.39	100%	44.5°
2042-01-07 Tue	34	—	unknown	19:15–01:40 (marginal, 6.42 h)	42.9° 22:50	11.37	97%	53.3°
2042-01-08 Wed	50	—	unknown	19:00–02:00 (marginal, 7.0 h)	42.9° 22:45	11.36	93%	62.8°
2042-01-09 Thu	82	—	unknown	19:25–23:00 (good, 3.58 h)	42.9° 22:40	11.34	88%	72.7°
2042-01-10 Fri	87	—	unknown	19:20–00:50 (good, 5.5 h)	42.9° 22:35	11.32	81%	82.7°
2042-01-11 Sat	89	—	unknown	19:20–01:25 (good, 6.08 h)	42.9° 22:30	11.3	73%	92.7°
2042-01-12 Sun	89	—	unknown	19:15–01:35 (good, 6.33 h)	42.9° 22:30	11.28	64%	102.6°
2042-01-13 Mon	89	—	unknown	19:10–01:35 (good, 6.42 h)	42.9° 22:25	11.26	55%	112.4°
2042-01-14 Tue	89	—	unknown	19:05–01:35 (good, 6.5 h)	42.9° 22:20	11.24	46%	122.0°
2042-01-15 Wed	89	—	unknown	19:05–01:35 (good, 6.5 h)	42.9° 22:15	11.22	36%	131.0°
2042-01-16 Thu	89	—	unknown	19:00–01:30 (good, 6.5 h)	42.9° 22:15	11.2	27%	139.0°
2042-01-17 Fri	89	—	unknown	19:00–01:30 (good, 6.5 h)	42.9° 22:10	11.18	18%	145.1°
2042-01-18 Sat	89	—	unknown	19:00–01:25 (good, 6.42 h)	42.9° 22:05	11.15	11%	147.5°
2042-01-19 Sun	89	—	unknown	19:00–01:20 (good, 6.33 h)	42.9° 22:00	11.13	5%	145.1°
2042-01-20 Mon	89	—	unknown	19:00–01:15 (good, 6.25 h)	42.9° 21:55	11.1	1%	138.4°
2042-01-21 Tue	89	—	unknown	19:00–01:10 (good, 6.17 h)	42.9° 21:55	11.08	0%	128.8°
2042-01-22 Wed	89	—	unknown	19:05–01:10 (good, 6.08 h)	42.9° 21:50	11.05	2%	117.6°
2042-01-23 Thu	89	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:45	11.03	6%	105.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-12-25&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.