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: 12-07 (89), 12-08 (89), 12-09 (89), 12-10 (89), 12-11 (89) — by astronomy; check the weather when the night is within four days.

2031-11-23astronomy score per night — click a bar for that night2031-12-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-11-23 Sun	88	—	unknown	23:05–05:05 (good, 6.0 h)	42.9° 01:45	11.16	75%	84.9°
2031-11-24 Mon	85	—	unknown	00:40–05:00 (good, 4.33 h)	42.9° 01:45	11.19	83%	72.9°
2031-11-25 Tue	69	—	unknown	04:35–05:00 (good, 0.42 h)	42.9° 01:40	11.21	90%	61.2°
2031-11-26 Wed	36	—	unknown	22:45–05:20 (marginal, 6.58 h)	42.9° 01:35	11.23	96%	50.1°
2031-11-27 Thu	22	—	unknown	01:15–04:55 (marginal, 3.67 h)	42.9° 01:30	11.25	99%	40.0°
2031-11-28 Fri	13	—	unknown	04:10–04:15 (marginal, 0.08 h)	42.9° 01:25	11.27	100%	31.7°
2031-11-29 Sat	10	—	unknown	—	42.9° 01:25	11.29	99%	26.5°
2031-11-30 Sun	12	—	unknown	—	42.9° 01:20	11.31	96%	26.2°
2031-12-01 Mon	18	—	unknown	22:10–00:25 (marginal, 2.25 h)	42.9° 01:15	11.33	92%	30.7°
2031-12-02 Tue	30	—	unknown	21:40–04:05 (marginal, 6.42 h)	42.9° 01:10	11.34	86%	38.3°
2031-12-03 Wed	46	—	unknown	21:25–04:25 (marginal, 7.0 h)	42.9° 01:10	11.36	79%	47.4°
2031-12-04 Thu	71	—	unknown	22:20–01:00 (good, 2.67 h)	42.9° 01:05	11.38	70%	57.2°
2031-12-05 Fri	84	—	unknown	21:45–03:15 (good, 5.5 h)	42.9° 01:00	11.39	62%	67.6°
2031-12-06 Sat	87	—	unknown	21:40–03:50 (good, 6.17 h)	42.9° 00:55	11.4	52%	78.2°
2031-12-07 Sun	89	—	unknown	21:40–04:00 (good, 6.33 h)	42.9° 00:50	11.42	42%	89.2°
2031-12-08 Mon	89	—	unknown	21:35–04:00 (good, 6.42 h)	42.9° 00:50	11.43	33%	100.5°
2031-12-09 Tue	89	—	unknown	21:30–04:00 (good, 6.5 h)	42.9° 00:45	11.44	23%	112.0°
2031-12-10 Wed	89	—	unknown	21:25–04:00 (good, 6.58 h)	42.9° 00:40	11.45	15%	123.6°
2031-12-11 Thu	89	—	unknown	21:20–03:55 (good, 6.58 h)	42.9° 00:35	11.46	8%	134.9°
2031-12-12 Fri	89	—	unknown	21:20–03:50 (good, 6.5 h)	42.9° 00:30	11.47	3%	145.3°
2031-12-13 Sat	89	—	unknown	21:15–03:45 (good, 6.5 h)	42.9° 00:30	11.48	0%	152.7°
2031-12-14 Sun	89	—	unknown	21:10–03:45 (good, 6.58 h)	42.9° 00:25	11.48	0%	153.8°
2031-12-15 Mon	89	—	unknown	21:05–03:40 (good, 6.58 h)	42.9° 00:20	11.49	4%	147.7°
2031-12-16 Tue	89	—	unknown	21:00–03:35 (good, 6.58 h)	42.9° 00:15	11.5	10%	137.4°
2031-12-17 Wed	89	—	unknown	21:00–03:30 (good, 6.5 h)	42.9° 00:15	11.5	18%	125.4°
2031-12-18 Thu	89	—	unknown	21:00–03:30 (good, 6.5 h)	42.9° 00:10	11.5	27%	112.8°
2031-12-19 Fri	89	—	unknown	21:00–03:25 (good, 6.42 h)	42.9° 00:05	11.51	38%	100.1°
2031-12-20 Sat	89	—	unknown	21:05–03:20 (good, 6.25 h)	42.9° 00:00	11.51	49%	87.6°
2031-12-21 Sun	86	—	unknown	21:15–03:15 (good, 6.0 h)	42.9° 23:55	11.51	60%	75.4°
2031-12-22 Mon	81	—	unknown	23:00–03:10 (good, 4.17 h)	42.9° 23:55	11.51	70%	63.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-11-23&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.