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 Andromeda Galaxy: 12-28 (100), 12-29 (100), 12-30 (100), 12-31 (100), 01-01 (100) — by astronomy; check the weather when the night is within four days.

2042-12-18astronomy score per night — click a bar for that night2043-01-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-12-18 Thu	93	—	unknown	18:35–01:25 (good, 6.83 h)	89.7° 19:15	11.5	38%	55.4°
2042-12-19 Fri	85	—	unknown	18:35–01:20 (good, 6.75 h)	89.5° 19:10	11.51	49%	45.4°
2042-12-20 Sat	65	—	unknown	18:35–00:45 (good, 6.17 h)	89.7° 19:10	11.51	60%	37.2°
2042-12-21 Sun	47	—	unknown	18:35–01:40 (marginal, 7.08 h)	89.8° 19:05	11.51	71%	32.5°
2042-12-22 Mon	32	—	unknown	18:35–01:15 (marginal, 6.67 h)	89.8° 19:00	11.51	81%	33.1°
2042-12-23 Tue	27	—	unknown	18:40–00:55 (marginal, 6.25 h)	89.6° 18:55	11.51	89%	38.9°
2042-12-24 Wed	31	—	unknown	18:40–00:40 (marginal, 6.0 h)	89.5° 18:55	11.5	95%	48.1°
2042-12-25 Thu	42	—	unknown	18:40–00:40 (marginal, 6.0 h)	89.7° 18:50	11.5	99%	59.0°
2042-12-26 Fri	59	—	unknown	18:40–20:00 (good, 1.33 h)	89.8° 18:45	11.5	100%	70.6°
2042-12-27 Sat	75	—	unknown	18:40–22:15 (good, 3.58 h)	89.7° 18:40	11.49	98%	82.4°
2042-12-28 Sun	100	—	unknown	18:40–23:40 (good, 5.0 h)	89.6° 18:35	11.48	94%	94.0°
2042-12-29 Mon	100	—	unknown	18:40–00:20 (good, 5.67 h)	89.6° 18:35	11.48	88%	105.3°
2042-12-30 Tue	100	—	unknown	18:40–00:25 (good, 5.75 h)	89.8° 18:30	11.47	80%	115.9°
2042-12-31 Wed	100	—	unknown	18:45–00:25 (good, 5.67 h)	89.8° 18:25	11.46	72%	125.8°
2043-01-01 Thu	100	—	unknown	18:45–00:25 (good, 5.67 h)	89.7° 18:20	11.45	62%	134.6°
2043-01-02 Fri	100	—	unknown	18:45–00:25 (good, 5.67 h)	89.5° 18:15	11.44	53%	141.8°
2043-01-03 Sat	100	—	unknown	18:45–00:20 (good, 5.58 h)	89.6° 18:15	11.43	44%	146.6°
2043-01-04 Sun	100	—	unknown	18:45–00:20 (good, 5.58 h)	89.8° 18:10	11.42	34%	148.0°
2043-01-05 Mon	100	—	unknown	18:45–00:15 (good, 5.5 h)	89.8° 18:05	11.4	26%	145.6°
2043-01-06 Tue	100	—	unknown	18:50–00:10 (good, 5.33 h)	89.6° 18:00	11.39	18%	140.0°
2043-01-07 Wed	100	—	unknown	18:50–00:05 (good, 5.25 h)	89.5° 18:00	11.38	11%	132.2°
2043-01-08 Thu	100	—	unknown	18:50–00:05 (good, 5.25 h)	89.7° 17:55	11.36	6%	123.1°
2043-01-09 Fri	100	—	unknown	18:50–00:00 (good, 5.17 h)	89.8° 17:50	11.34	2%	113.0°
2043-01-10 Sat	100	—	unknown	18:50–23:55 (good, 5.08 h)	89.7° 17:45	11.33	0%	102.3°
2043-01-11 Sun	100	—	unknown	18:50–23:50 (good, 5.0 h)	89.6° 17:40	11.31	1%	91.2°
2043-01-12 Mon	100	—	unknown	18:55–23:45 (good, 4.83 h)	89.6° 17:40	11.29	3%	79.9°
2043-01-13 Tue	100	—	unknown	18:55–23:45 (good, 4.83 h)	89.7° 17:35	11.27	8%	68.6°
2043-01-14 Wed	96	—	unknown	18:55–23:40 (good, 4.75 h)	89.8° 17:30	11.25	15%	57.5°
2043-01-15 Thu	89	—	unknown	18:55–23:35 (good, 4.67 h)	89.7° 17:25	11.23	24%	47.2°
2043-01-16 Fri	81	—	unknown	18:55–23:30 (good, 4.58 h)	89.5° 17:20	11.21	34%	38.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-12-18&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.