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

2040-11-09astronomy score per night — click a bar for that night2040-12-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-11-09 Fri	89	—	unknown	23:25–05:30 (good, 6.08 h)	42.9° 02:40	10.8	31%	134.4°
2040-11-10 Sat	89	—	unknown	23:20–05:35 (good, 6.25 h)	42.9° 02:35	10.83	42%	123.9°
2040-11-11 Sun	89	—	unknown	23:25–05:35 (good, 6.17 h)	42.9° 02:30	10.86	53%	112.4°
2040-11-12 Mon	89	—	unknown	23:25–05:35 (good, 6.17 h)	42.9° 02:25	10.89	64%	100.6°
2040-11-13 Tue	89	—	unknown	23:35–05:35 (good, 6.0 h)	42.9° 02:25	10.92	75%	88.8°
2040-11-14 Wed	88	—	unknown	00:25–05:35 (good, 5.17 h)	42.9° 02:20	10.95	84%	77.0°
2040-11-15 Thu	83	—	unknown	02:45–05:35 (good, 2.83 h)	42.9° 02:15	10.98	91%	65.6°
2040-11-16 Fri	48	—	unknown	23:10–05:40 (marginal, 6.5 h)	42.9° 02:10	11.0	96%	54.9°
2040-11-17 Sat	28	—	unknown	00:20–05:40 (marginal, 5.33 h)	42.9° 02:10	11.03	99%	45.2°
2040-11-18 Sun	17	—	unknown	03:05–05:15 (marginal, 2.17 h)	42.9° 02:05	11.06	100%	37.2°
2040-11-19 Mon	12	—	unknown	—	42.9° 02:00	11.08	99%	32.2°
2040-11-20 Tue	11	—	unknown	—	42.9° 01:55	11.11	95%	31.3°
2040-11-21 Wed	17	—	unknown	22:55–01:00 (marginal, 2.08 h)	42.9° 01:50	11.13	90%	34.5°
2040-11-22 Thu	28	—	unknown	22:25–04:45 (marginal, 6.33 h)	42.9° 01:50	11.16	84%	40.8°
2040-11-23 Fri	43	—	unknown	22:05–05:05 (marginal, 7.0 h)	42.9° 01:45	11.18	76%	48.9°
2040-11-24 Sat	61	—	unknown	23:00–00:55 (good, 1.92 h)	42.9° 01:40	11.2	68%	57.9°
2040-11-25 Sun	72	—	unknown	22:20–03:40 (good, 5.33 h)	42.9° 01:35	11.23	59%	67.5°
2040-11-26 Mon	85	—	unknown	22:20–04:25 (good, 6.08 h)	42.9° 01:30	11.25	50%	77.5°
2040-11-27 Tue	88	—	unknown	22:15–04:35 (good, 6.33 h)	42.9° 01:30	11.27	40%	87.8°
2040-11-28 Wed	89	—	unknown	22:10–04:35 (good, 6.42 h)	42.9° 01:25	11.29	31%	98.4°
2040-11-29 Thu	89	—	unknown	22:05–04:35 (good, 6.5 h)	42.9° 01:20	11.31	22%	109.0°
2040-11-30 Fri	89	—	unknown	22:00–04:35 (good, 6.58 h)	42.9° 01:15	11.32	14%	119.8°
2040-12-01 Sat	89	—	unknown	22:00–04:30 (good, 6.5 h)	42.9° 01:15	11.34	7%	130.2°
2040-12-02 Sun	89	—	unknown	21:55–04:30 (good, 6.58 h)	42.9° 01:10	11.36	2%	139.6°
2040-12-03 Mon	89	—	unknown	21:50–04:25 (good, 6.58 h)	42.9° 01:05	11.37	0%	146.6°
2040-12-04 Tue	89	—	unknown	21:45–04:20 (good, 6.58 h)	42.9° 01:00	11.39	1%	148.9°
2040-12-05 Wed	89	—	unknown	21:45–04:15 (good, 6.5 h)	42.9° 00:55	11.4	4%	145.4°
2040-12-06 Thu	89	—	unknown	21:40–04:10 (good, 6.5 h)	42.9° 00:55	11.42	10%	137.4°
2040-12-07 Fri	89	—	unknown	21:35–04:10 (good, 6.58 h)	42.9° 00:50	11.43	18%	126.9°
2040-12-08 Sat	89	—	unknown	21:30–04:05 (good, 6.58 h)	42.9° 00:45	11.44	27%	115.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-11-09&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.