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: 01-01 (100), 01-02 (100), 01-03 (100), 01-04 (100), 01-05 (100) — by astronomy; check the weather when the night is within four days.

2039-12-23astronomy score per night — click a bar for that night2040-01-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-12-23 Fri	60	—	unknown	21:40–21:45 (good, 0.08 h)	89.5° 19:00	11.51	65%	38.4°
2039-12-24 Sat	44	—	unknown	18:40–01:25 (marginal, 6.75 h)	89.7° 18:55	11.5	74%	37.0°
2039-12-25 Sun	35	—	unknown	18:40–01:10 (marginal, 6.5 h)	89.8° 18:50	11.5	82%	39.1°
2039-12-26 Mon	33	—	unknown	18:40–00:50 (marginal, 6.17 h)	89.7° 18:45	11.5	89%	43.9°
2039-12-27 Tue	34	—	unknown	18:40–00:40 (marginal, 6.0 h)	89.6° 18:40	11.49	94%	50.7°
2039-12-28 Wed	41	—	unknown	18:40–00:35 (marginal, 5.92 h)	89.6° 18:40	11.49	98%	58.6°
2039-12-29 Thu	51	—	unknown	18:40–19:10 (good, 0.5 h)	89.7° 18:35	11.48	100%	67.4°
2039-12-30 Fri	65	—	unknown	18:40–21:15 (good, 2.58 h)	89.8° 18:30	11.47	100%	76.5°
2039-12-31 Sat	77	—	unknown	18:45–22:25 (good, 3.67 h)	89.7° 18:25	11.46	98%	86.0°
2040-01-01 Sun	100	—	unknown	18:45–23:30 (good, 4.75 h)	89.5° 18:20	11.45	95%	95.5°
2040-01-02 Mon	100	—	unknown	18:45–00:05 (good, 5.33 h)	89.6° 18:20	11.44	90%	105.1°
2040-01-03 Tue	100	—	unknown	18:45–00:10 (good, 5.42 h)	89.8° 18:15	11.43	83%	114.5°
2040-01-04 Wed	100	—	unknown	18:45–00:10 (good, 5.42 h)	89.8° 18:10	11.42	75%	123.5°
2040-01-05 Thu	100	—	unknown	18:45–00:10 (good, 5.42 h)	89.7° 18:05	11.41	66%	131.6°
2040-01-06 Fri	100	—	unknown	18:45–00:05 (good, 5.33 h)	89.5° 18:05	11.39	56%	138.3°
2040-01-07 Sat	100	—	unknown	18:50–00:05 (good, 5.25 h)	89.7° 18:00	11.38	45%	142.4°
2040-01-08 Sun	100	—	unknown	18:50–00:05 (good, 5.25 h)	89.8° 17:55	11.36	34%	142.6°
2040-01-09 Mon	100	—	unknown	18:50–00:00 (good, 5.17 h)	89.8° 17:50	11.35	24%	138.6°
2040-01-10 Tue	100	—	unknown	18:50–23:55 (good, 5.08 h)	89.6° 17:45	11.33	15%	131.1°
2040-01-11 Wed	100	—	unknown	18:50–23:50 (good, 5.0 h)	89.6° 17:45	11.31	7%	121.2°
2040-01-12 Thu	100	—	unknown	18:55–23:50 (good, 4.92 h)	89.7° 17:40	11.29	2%	109.9°
2040-01-13 Fri	100	—	unknown	18:55–23:45 (good, 4.83 h)	89.8° 17:35	11.27	0%	98.0°
2040-01-14 Sat	100	—	unknown	18:55–23:40 (good, 4.75 h)	89.7° 17:30	11.25	1%	85.9°
2040-01-15 Sun	100	—	unknown	18:55–23:35 (good, 4.67 h)	89.5° 17:25	11.23	5%	74.1°
2040-01-16 Mon	100	—	unknown	18:55–23:30 (good, 4.58 h)	89.6° 17:25	11.21	11%	63.0°
2040-01-17 Tue	93	—	unknown	19:00–23:30 (good, 4.5 h)	89.8° 17:20	11.19	19%	53.1°
2040-01-18 Wed	86	—	unknown	19:00–23:25 (good, 4.42 h)	89.8° 17:15	11.17	28%	44.9°
2040-01-19 Thu	71	—	unknown	19:00–23:05 (good, 4.08 h)	89.7° 17:10	11.14	38%	39.3°
2040-01-20 Fri	54	—	unknown	19:00–22:45 (good, 3.75 h)	89.5° 17:05	11.12	48%	36.9°
2040-01-21 Sat	41	—	unknown	19:25–19:55 (good, 0.5 h)	89.7° 17:05	11.09	58%	38.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-12-23&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.