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: 11-12 (89), 11-13 (89), 11-14 (89), 11-15 (89), 11-16 (89) — by astronomy; check the weather when the night is within four days.

2039-11-09astronomy score per night — click a bar for that night2039-12-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-11-09 Wed	81	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:40	10.77	42%	69.3°
2039-11-10 Thu	86	—	unknown	23:25–05:30 (good, 6.08 h)	42.9° 02:40	10.8	33%	80.2°
2039-11-11 Fri	88	—	unknown	23:20–05:35 (good, 6.25 h)	42.9° 02:35	10.83	23%	91.6°
2039-11-12 Sat	89	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:30	10.87	15%	103.4°
2039-11-13 Sun	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:25	10.9	8%	115.4°
2039-11-14 Mon	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:20	10.93	3%	127.2°
2039-11-15 Tue	89	—	unknown	23:05–05:35 (good, 6.5 h)	42.9° 02:20	10.95	0%	138.1°
2039-11-16 Wed	89	—	unknown	23:00–05:35 (good, 6.58 h)	42.9° 02:15	10.98	1%	146.8°
2039-11-17 Thu	89	—	unknown	22:55–05:30 (good, 6.58 h)	42.9° 02:10	11.01	4%	150.6°
2039-11-18 Fri	89	—	unknown	22:55–05:25 (good, 6.5 h)	42.9° 02:05	11.04	10%	147.7°
2039-11-19 Sat	89	—	unknown	22:50–05:20 (good, 6.5 h)	42.9° 02:05	11.06	19%	139.8°
2039-11-20 Sun	89	—	unknown	22:45–05:20 (good, 6.58 h)	42.9° 02:00	11.09	29%	129.5°
2039-11-21 Mon	89	—	unknown	22:40–05:15 (good, 6.58 h)	42.9° 01:55	11.12	39%	118.1°
2039-11-22 Tue	89	—	unknown	22:45–05:10 (good, 6.42 h)	42.9° 01:50	11.14	50%	106.6°
2039-11-23 Wed	89	—	unknown	22:50–05:05 (good, 6.25 h)	42.9° 01:45	11.16	61%	95.0°
2039-11-24 Thu	89	—	unknown	22:55–05:00 (good, 6.08 h)	42.9° 01:45	11.19	71%	83.7°
2039-11-25 Fri	87	—	unknown	00:00–05:00 (good, 5.0 h)	42.9° 01:40	11.21	80%	72.8°
2039-11-26 Sat	83	—	unknown	02:25–04:55 (good, 2.5 h)	42.9° 01:35	11.23	87%	62.2°
2039-11-27 Sun	46	—	unknown	22:30–05:20 (marginal, 6.83 h)	42.9° 01:30	11.25	93%	52.2°
2039-11-28 Mon	28	—	unknown	23:35–05:00 (marginal, 5.42 h)	42.9° 01:25	11.27	97%	43.2°
2039-11-29 Tue	17	—	unknown	02:25–04:35 (marginal, 2.17 h)	42.9° 01:25	11.29	99%	35.7°
2039-11-30 Wed	11	—	unknown	—	42.9° 01:20	11.31	100%	30.7°
2039-12-01 Thu	9	—	unknown	—	42.9° 01:15	11.33	99%	29.6°
2039-12-02 Fri	13	—	unknown	—	42.9° 01:10	11.35	96%	32.6°
2039-12-03 Sat	22	—	unknown	21:55–02:20 (marginal, 4.42 h)	42.9° 01:10	11.36	91%	38.8°
2039-12-04 Sun	35	—	unknown	21:30–04:10 (marginal, 6.67 h)	42.9° 01:05	11.38	85%	46.9°
2039-12-05 Mon	52	—	unknown	21:15–04:25 (marginal, 7.17 h)	42.9° 01:00	11.39	77%	56.2°
2039-12-06 Tue	67	—	unknown	22:05–02:00 (good, 3.92 h)	42.9° 00:55	11.41	69%	66.2°
2039-12-07 Wed	84	—	unknown	21:40–03:40 (good, 6.0 h)	42.9° 00:50	11.42	59%	76.7°
2039-12-08 Thu	88	—	unknown	21:35–03:50 (good, 6.25 h)	42.9° 00:50	11.43	49%	87.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-11-09&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.