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: 11-18 (89), 11-19 (89), 12-02 (89), 12-03 (89), 12-04 (89) — by astronomy; check the weather when the night is within four days.

2026-11-18astronomy score per night — click a bar for that night2026-12-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-11-18 Wed	89	—	unknown	23:05–05:25 (good, 6.33 h)	42.9° 02:05	11.04	64%	99.6°
2026-11-19 Thu	89	—	unknown	23:15–05:20 (good, 6.08 h)	42.9° 02:00	11.07	74%	88.8°
2026-11-20 Fri	86	—	unknown	00:15–05:15 (good, 5.0 h)	42.9° 02:00	11.09	82%	77.7°
2026-11-21 Sat	81	—	unknown	03:00–05:15 (good, 2.25 h)	42.9° 01:55	11.12	90%	66.4°
2026-11-22 Sun	40	—	unknown	22:50–05:35 (marginal, 6.75 h)	42.9° 01:50	11.14	96%	55.3°
2026-11-23 Mon	24	—	unknown	00:40–05:15 (marginal, 4.58 h)	42.9° 01:45	11.17	99%	45.1°
2026-11-24 Tue	14	—	unknown	04:05–04:35 (marginal, 0.5 h)	42.9° 01:40	11.19	100%	37.0°
2026-11-25 Wed	11	—	unknown	—	42.9° 01:40	11.21	97%	33.1°
2026-11-26 Thu	17	—	unknown	22:40–00:20 (marginal, 1.67 h)	42.9° 01:35	11.23	92%	35.1°
2026-11-27 Fri	30	—	unknown	22:00–04:30 (marginal, 6.5 h)	42.9° 01:30	11.26	84%	41.9°
2026-11-28 Sat	49	—	unknown	21:40–04:50 (marginal, 7.17 h)	42.9° 01:25	11.28	75%	51.5°
2026-11-29 Sun	69	—	unknown	22:30–02:30 (good, 4.0 h)	42.9° 01:20	11.3	65%	62.2°
2026-11-30 Mon	85	—	unknown	22:05–04:10 (good, 6.08 h)	42.9° 01:20	11.31	54%	73.4°
2026-12-01 Tue	88	—	unknown	22:00–04:20 (good, 6.33 h)	42.9° 01:15	11.33	43%	84.6°
2026-12-02 Wed	89	—	unknown	21:55–04:20 (good, 6.42 h)	42.9° 01:10	11.35	33%	95.7°
2026-12-03 Thu	89	—	unknown	21:50–04:20 (good, 6.5 h)	42.9° 01:05	11.36	23%	106.4°
2026-12-04 Fri	89	—	unknown	21:50–04:20 (good, 6.5 h)	42.9° 01:05	11.38	16%	116.6°
2026-12-05 Sat	89	—	unknown	21:45–04:20 (good, 6.58 h)	42.9° 01:00	11.39	9%	126.1°
2026-12-06 Sun	89	—	unknown	21:40–04:15 (good, 6.58 h)	42.9° 00:55	11.41	4%	134.6°
2026-12-07 Mon	89	—	unknown	21:35–04:10 (good, 6.58 h)	42.9° 00:50	11.42	1%	141.5°
2026-12-08 Tue	89	—	unknown	21:35–04:05 (good, 6.5 h)	42.9° 00:45	11.43	0%	145.9°
2026-12-09 Wed	89	—	unknown	21:30–04:00 (good, 6.5 h)	42.9° 00:45	11.44	1%	146.9°
2026-12-10 Thu	89	—	unknown	21:25–04:00 (good, 6.58 h)	42.9° 00:40	11.45	3%	144.2°
2026-12-11 Fri	89	—	unknown	21:20–03:55 (good, 6.58 h)	42.9° 00:35	11.46	7%	138.6°
2026-12-12 Sat	89	—	unknown	21:15–03:50 (good, 6.58 h)	42.9° 00:30	11.47	13%	131.1°
2026-12-13 Sun	89	—	unknown	21:15–03:45 (good, 6.5 h)	42.9° 00:25	11.48	20%	122.4°
2026-12-14 Mon	89	—	unknown	21:10–03:40 (good, 6.5 h)	42.9° 00:25	11.49	28%	113.0°
2026-12-15 Tue	89	—	unknown	21:10–03:40 (good, 6.5 h)	42.9° 00:20	11.49	37%	103.0°
2026-12-16 Wed	89	—	unknown	21:15–03:35 (good, 6.33 h)	42.9° 00:15	11.5	47%	92.6°
2026-12-17 Thu	88	—	unknown	21:20–03:30 (good, 6.17 h)	42.9° 00:10	11.5	57%	81.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-11-18&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.