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: 12-21 (100), 12-22 (100), 12-23 (100), 12-24 (100), 12-25 (100) — by astronomy; check the weather when the night is within four days.

2027-12-21astronomy score per night — click a bar for that night2028-01-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-12-21 Tue	100	—	unknown	18:35–01:15 (good, 6.67 h)	89.7° 19:05	11.51	33%	150.7°
2027-12-22 Wed	100	—	unknown	18:35–01:10 (good, 6.58 h)	89.6° 19:00	11.51	24%	151.5°
2027-12-23 Thu	100	—	unknown	18:40–01:05 (good, 6.42 h)	89.5° 18:55	11.51	15%	147.0°
2027-12-24 Fri	100	—	unknown	18:40–01:00 (good, 6.33 h)	89.6° 18:55	11.5	8%	139.1°
2027-12-25 Sat	100	—	unknown	18:40–01:00 (good, 6.33 h)	89.7° 18:50	11.5	4%	129.6°
2027-12-26 Sun	100	—	unknown	18:40–00:55 (good, 6.25 h)	89.7° 18:45	11.5	1%	119.3°
2027-12-27 Mon	100	—	unknown	18:40–00:50 (good, 6.17 h)	89.6° 18:40	11.49	0%	108.7°
2027-12-28 Tue	100	—	unknown	18:40–00:45 (good, 6.08 h)	89.5° 18:40	11.49	1%	98.0°
2027-12-29 Wed	100	—	unknown	18:40–00:40 (good, 6.0 h)	89.6° 18:35	11.48	4%	87.3°
2027-12-30 Thu	100	—	unknown	18:40–00:40 (good, 6.0 h)	89.7° 18:30	11.47	9%	76.8°
2027-12-31 Fri	100	—	unknown	18:45–00:35 (good, 5.83 h)	89.7° 18:25	11.46	15%	66.5°
2028-01-01 Sat	96	—	unknown	18:45–00:30 (good, 5.75 h)	89.6° 18:20	11.45	22%	56.6°
2028-01-02 Sun	89	—	unknown	18:45–00:25 (good, 5.67 h)	89.5° 18:20	11.44	30%	47.1°
2028-01-03 Mon	81	—	unknown	18:45–00:25 (good, 5.67 h)	89.7° 18:15	11.43	39%	38.6°
2028-01-04 Tue	69	—	unknown	18:45–23:50 (good, 5.08 h)	89.7° 18:10	11.42	49%	31.8°
2028-01-05 Wed	51	—	unknown	18:45–00:45 (marginal, 6.0 h)	89.7° 18:05	11.41	58%	28.3°
2028-01-06 Thu	35	—	unknown	18:45–00:30 (marginal, 5.75 h)	89.5° 18:00	11.4	68%	29.6°
2028-01-07 Fri	27	—	unknown	18:50–00:10 (marginal, 5.33 h)	89.6° 18:00	11.38	78%	35.6°
2028-01-08 Sat	26	—	unknown	18:50–23:55 (marginal, 5.08 h)	89.7° 17:55	11.37	86%	44.7°
2028-01-09 Sun	31	—	unknown	18:50–23:50 (marginal, 5.0 h)	89.7° 17:50	11.35	93%	55.8°
2028-01-10 Mon	41	—	unknown	18:50–23:55 (marginal, 5.08 h)	89.6° 17:45	11.33	98%	68.1°
2028-01-11 Tue	56	—	unknown	18:50–21:00 (good, 2.17 h)	89.5° 17:45	11.31	100%	81.0°
2028-01-12 Wed	75	—	unknown	18:55–22:25 (good, 3.5 h)	89.6° 17:40	11.3	99%	94.3°
2028-01-13 Thu	100	—	unknown	18:55–23:20 (good, 4.42 h)	89.7° 17:35	11.28	95%	107.6°
2028-01-14 Fri	100	—	unknown	18:55–23:30 (good, 4.58 h)	89.7° 17:30	11.26	89%	120.4°
2028-01-15 Sat	100	—	unknown	18:55–23:25 (good, 4.5 h)	89.6° 17:25	11.24	80%	132.3°
2028-01-16 Sun	100	—	unknown	18:55–23:25 (good, 4.5 h)	89.5° 17:25	11.21	70%	142.6°
2028-01-17 Mon	100	—	unknown	19:00–23:30 (good, 4.5 h)	89.7° 17:20	11.19	60%	149.8°
2028-01-18 Tue	100	—	unknown	19:00–23:25 (good, 4.42 h)	89.7° 17:15	11.17	49%	151.9°
2028-01-19 Wed	100	—	unknown	19:00–23:20 (good, 4.33 h)	89.7° 17:10	11.14	38%	148.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-12-21&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.