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.

2040-12-18astronomy score per night — click a bar for that night2041-01-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-12-18 Tue	62	—	unknown	18:35–19:45 (good, 1.17 h)	89.8° 19:15	11.51	100%	67.0°
2040-12-19 Wed	73	—	unknown	18:35–22:05 (good, 3.5 h)	89.8° 19:10	11.51	98%	76.6°
2040-12-20 Thu	81	—	unknown	18:35–23:15 (good, 4.67 h)	89.7° 19:05	11.51	94%	86.3°
2040-12-21 Fri	100	—	unknown	18:35–00:25 (good, 5.83 h)	89.5° 19:05	11.51	89%	95.9°
2040-12-22 Sat	100	—	unknown	18:35–00:45 (good, 6.17 h)	89.7° 19:00	11.51	83%	105.5°
2040-12-23 Sun	100	—	unknown	18:40–00:50 (good, 6.17 h)	89.8° 18:55	11.5	75%	114.8°
2040-12-24 Mon	100	—	unknown	18:40–00:50 (good, 6.17 h)	89.8° 18:50	11.5	67%	123.6°
2040-12-25 Tue	100	—	unknown	18:40–00:50 (good, 6.17 h)	89.6° 18:45	11.5	58%	131.7°
2040-12-26 Wed	100	—	unknown	18:40–00:50 (good, 6.17 h)	89.6° 18:45	11.49	48%	138.6°
2040-12-27 Thu	100	—	unknown	18:40–00:50 (good, 6.17 h)	89.7° 18:40	11.49	38%	143.2°
2040-12-28 Fri	100	—	unknown	18:40–00:45 (good, 6.08 h)	89.8° 18:35	11.48	28%	144.4°
2040-12-29 Sat	100	—	unknown	18:40–00:40 (good, 6.0 h)	89.7° 18:30	11.47	19%	141.5°
2040-12-30 Sun	100	—	unknown	18:40–00:35 (good, 5.92 h)	89.6° 18:25	11.47	11%	135.0°
2040-12-31 Mon	100	—	unknown	18:45–00:30 (good, 5.75 h)	89.6° 18:25	11.46	5%	125.8°
2041-01-01 Tue	100	—	unknown	18:45–00:30 (good, 5.75 h)	89.8° 18:20	11.45	1%	114.9°
2041-01-02 Wed	100	—	unknown	18:45–00:25 (good, 5.67 h)	89.8° 18:15	11.44	0%	103.1°
2041-01-03 Thu	100	—	unknown	18:45–00:20 (good, 5.58 h)	89.7° 18:10	11.42	2%	90.8°
2041-01-04 Fri	100	—	unknown	18:45–00:15 (good, 5.5 h)	89.5° 18:05	11.41	7%	78.5°
2041-01-05 Sat	100	—	unknown	18:45–00:10 (good, 5.42 h)	89.7° 18:05	11.4	14%	66.7°
2041-01-06 Sun	94	—	unknown	18:50–00:10 (good, 5.33 h)	89.8° 18:00	11.38	24%	55.7°
2041-01-07 Mon	84	—	unknown	18:50–00:05 (good, 5.25 h)	89.8° 17:55	11.37	34%	46.3°
2041-01-08 Tue	74	—	unknown	18:50–23:40 (good, 4.83 h)	89.6° 17:50	11.35	45%	39.3°
2041-01-09 Wed	56	—	unknown	18:50–22:05 (good, 3.25 h)	89.5° 17:50	11.34	56%	35.7°
2041-01-10 Thu	40	—	unknown	18:50–00:15 (marginal, 5.42 h)	89.7° 17:45	11.32	66%	36.2°
2041-01-11 Fri	31	—	unknown	18:55–00:00 (marginal, 5.08 h)	89.8° 17:40	11.3	75%	40.5°
2041-01-12 Sat	29	—	unknown	18:55–23:45 (marginal, 4.83 h)	89.7° 17:35	11.28	83%	47.3°
2041-01-13 Sun	30	—	unknown	18:55–23:35 (marginal, 4.67 h)	89.6° 17:30	11.26	90%	55.5°
2041-01-14 Mon	35	—	unknown	18:55–23:35 (marginal, 4.67 h)	89.6° 17:30	11.24	95%	64.6°
2041-01-15 Tue	43	—	unknown	18:55–19:40 (good, 0.75 h)	89.8° 17:25	11.22	98%	74.1°
2041-01-16 Wed	54	—	unknown	18:55–20:55 (good, 2.0 h)	89.8° 17:20	11.2	100%	83.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-18&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.