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: 12-25 (100), 12-26 (100), 12-27 (100), 12-28 (100), 12-29 (100) — by astronomy; check the weather when the night is within four days.

2026-12-18astronomy score per night — click a bar for that night2027-01-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-12-18 Fri	55	—	unknown	18:35–01:55 (marginal, 7.33 h)	89.7° 19:15	11.5	67%	30.8°
2026-12-19 Sat	36	—	unknown	18:35–01:35 (marginal, 7.0 h)	89.5° 19:10	11.51	77%	28.7°
2026-12-20 Sun	26	—	unknown	18:35–01:10 (marginal, 6.58 h)	89.5° 19:10	11.51	86%	32.6°
2026-12-21 Mon	27	—	unknown	18:35–00:50 (marginal, 6.25 h)	89.7° 19:05	11.51	93%	41.1°
2026-12-22 Tue	36	—	unknown	18:35–00:45 (marginal, 6.17 h)	89.7° 19:00	11.51	98%	52.3°
2026-12-23 Wed	52	—	unknown	18:40–18:55 (good, 0.25 h)	89.6° 18:55	11.51	100%	64.8°
2026-12-24 Thu	72	—	unknown	18:40–21:50 (good, 3.17 h)	89.5° 18:50	11.5	99%	78.0°
2026-12-25 Fri	100	—	unknown	18:40–23:30 (good, 4.83 h)	89.6° 18:50	11.5	95%	91.4°
2026-12-26 Sat	100	—	unknown	18:40–00:30 (good, 5.83 h)	89.7° 18:45	11.5	88%	104.4°
2026-12-27 Sun	100	—	unknown	18:40–00:35 (good, 5.92 h)	89.7° 18:40	11.49	79%	116.9°
2026-12-28 Mon	100	—	unknown	18:40–00:35 (good, 5.92 h)	89.6° 18:35	11.49	70%	128.5°
2026-12-29 Tue	100	—	unknown	18:40–00:35 (good, 5.92 h)	89.5° 18:35	11.48	59%	138.7°
2026-12-30 Wed	100	—	unknown	18:40–00:35 (good, 5.92 h)	89.6° 18:30	11.47	48%	146.6°
2026-12-31 Thu	100	—	unknown	18:45–00:35 (good, 5.83 h)	89.7° 18:25	11.46	38%	151.0°
2027-01-01 Fri	100	—	unknown	18:45–00:30 (good, 5.75 h)	89.7° 18:20	11.45	29%	150.6°
2027-01-02 Sat	100	—	unknown	18:45–00:25 (good, 5.67 h)	89.5° 18:15	11.44	20%	145.8°
2027-01-03 Sun	100	—	unknown	18:45–00:20 (good, 5.58 h)	89.5° 18:15	11.43	13%	138.4°
2027-01-04 Mon	100	—	unknown	18:45–00:20 (good, 5.58 h)	89.7° 18:10	11.42	8%	129.5°
2027-01-05 Tue	100	—	unknown	18:45–00:15 (good, 5.5 h)	89.7° 18:05	11.41	3%	119.8°
2027-01-06 Wed	100	—	unknown	18:50–00:10 (good, 5.33 h)	89.6° 18:00	11.39	1%	109.8°
2027-01-07 Thu	100	—	unknown	18:50–00:05 (good, 5.25 h)	89.5° 17:55	11.38	0%	99.5°
2027-01-08 Fri	100	—	unknown	18:50–00:00 (good, 5.17 h)	89.6° 17:55	11.36	1%	89.1°
2027-01-09 Sat	100	—	unknown	18:50–00:00 (good, 5.17 h)	89.7° 17:50	11.35	4%	78.7°
2027-01-10 Sun	100	—	unknown	18:50–23:55 (good, 5.08 h)	89.7° 17:45	11.33	8%	68.3°
2027-01-11 Mon	97	—	unknown	18:50–23:50 (good, 5.0 h)	89.6° 17:40	11.31	14%	58.1°
2027-01-12 Tue	91	—	unknown	18:55–23:45 (good, 4.83 h)	89.5° 17:40	11.29	22%	48.3°
2027-01-13 Wed	84	—	unknown	18:55–23:40 (good, 4.75 h)	89.6° 17:35	11.27	31%	39.3°
2027-01-14 Thu	70	—	unknown	18:55–23:20 (good, 4.42 h)	89.7° 17:30	11.25	40%	32.1°
2027-01-15 Fri	52	—	unknown	18:55–21:55 (good, 3.0 h)	89.7° 17:25	11.23	51%	28.6°
2027-01-16 Sat	36	—	unknown	18:55–23:55 (marginal, 5.0 h)	89.5° 17:20	11.21	62%	30.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-12-18&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.