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: 01-09 (89), 01-10 (89), 01-11 (89), 01-12 (89), 01-13 (89) — by astronomy; check the weather when the night is within four days.

2045-01-09astronomy score per night — click a bar for that night2045-02-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-01-09 Mon	89	—	unknown	19:25–01:50 (good, 6.42 h)	42.9° 22:40	11.33	52%	109.5°
2045-01-10 Tue	89	—	unknown	19:20–01:55 (good, 6.58 h)	42.9° 22:35	11.32	42%	119.8°
2045-01-11 Wed	89	—	unknown	19:15–01:50 (good, 6.58 h)	42.9° 22:30	11.3	32%	129.1°
2045-01-12 Thu	89	—	unknown	19:15–01:45 (good, 6.5 h)	42.9° 22:30	11.28	23%	137.2°
2045-01-13 Fri	89	—	unknown	19:10–01:45 (good, 6.58 h)	42.9° 22:25	11.26	16%	143.2°
2045-01-14 Sat	89	—	unknown	19:05–01:40 (good, 6.58 h)	42.9° 22:20	11.24	9%	146.3°
2045-01-15 Sun	89	—	unknown	19:00–01:35 (good, 6.58 h)	42.9° 22:15	11.22	5%	145.7°
2045-01-16 Mon	89	—	unknown	19:00–01:30 (good, 6.5 h)	42.9° 22:10	11.19	2%	141.8°
2045-01-17 Tue	89	—	unknown	19:00–01:25 (good, 6.42 h)	42.9° 22:10	11.17	0%	135.4°
2045-01-18 Wed	89	—	unknown	19:00–01:25 (good, 6.42 h)	42.9° 22:05	11.15	0%	127.5°
2045-01-19 Thu	89	—	unknown	19:00–01:20 (good, 6.33 h)	42.9° 22:00	11.12	3%	118.6°
2045-01-20 Fri	89	—	unknown	19:00–01:15 (good, 6.25 h)	42.9° 21:55	11.1	7%	109.1°
2045-01-21 Sat	89	—	unknown	19:05–01:10 (good, 6.08 h)	42.9° 21:50	11.07	12%	99.2°
2045-01-22 Sun	89	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:50	11.05	19%	89.1°
2045-01-23 Mon	88	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:45	11.02	27%	78.8°
2045-01-24 Tue	83	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:40	10.99	37%	68.5°
2045-01-25 Wed	70	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:35	10.96	47%	58.4°
2045-01-26 Thu	56	—	unknown	22:05–00:10 (good, 2.08 h)	42.9° 21:35	10.93	58%	48.8°
2045-01-27 Fri	37	—	unknown	19:10–01:10 (marginal, 6.0 h)	42.9° 21:30	10.9	68%	40.4°
2045-01-28 Sat	23	—	unknown	19:10–00:45 (marginal, 5.58 h)	42.9° 21:25	10.87	78%	34.8°
2045-01-29 Sun	14	—	unknown	19:10–20:30 (marginal, 1.33 h)	42.9° 21:20	10.84	87%	33.8°
2045-01-30 Mon	14	—	unknown	19:10–20:45 (marginal, 1.58 h)	42.9° 21:15	10.81	94%	38.3°
2045-01-31 Tue	20	—	unknown	19:15–22:55 (marginal, 3.67 h)	42.9° 21:15	10.78	99%	46.8°
2045-02-01 Wed	31	—	unknown	19:15–00:10 (marginal, 4.92 h)	42.9° 21:10	10.74	100%	57.7°
2045-02-02 Thu	46	—	unknown	19:15–19:40 (good, 0.42 h)	42.9° 21:05	10.71	98%	69.6°
2045-02-03 Fri	81	—	unknown	19:15–22:40 (good, 3.42 h)	42.9° 21:00	10.68	94%	81.9°
2045-02-04 Sat	89	—	unknown	19:20–23:50 (good, 4.5 h)	42.9° 20:55	10.64	87%	93.9°
2045-02-05 Sun	89	—	unknown	19:20–00:00 (good, 4.67 h)	42.9° 20:55	10.61	78%	105.6°
2045-02-06 Mon	89	—	unknown	19:20–00:00 (good, 4.67 h)	42.9° 20:50	10.57	69%	116.5°
2045-02-07 Tue	89	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.54	59%	126.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-01-09&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.