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: 08-21 (100), 08-22 (100), 08-23 (100), 08-24 (100), 08-25 (100) — by astronomy; check the weather when the night is within four days.

2041-08-20astronomy score per night — click a bar for that night2041-09-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-08-20 Tue	99	—	unknown	22:05–04:55 (good, 6.83 h)	89.6° 04:05	6.95	28%	60.3°
2041-08-21 Wed	100	—	unknown	22:00–04:55 (good, 6.92 h)	89.6° 04:05	7.01	20%	70.1°
2041-08-22 Thu	100	—	unknown	21:55–05:00 (good, 7.08 h)	89.8° 04:00	7.07	12%	80.0°
2041-08-23 Fri	100	—	unknown	21:55–05:00 (good, 7.08 h)	89.8° 03:55	7.12	7%	89.9°
2041-08-24 Sat	100	—	unknown	21:50–05:00 (good, 7.17 h)	89.7° 03:50	7.18	3%	99.8°
2041-08-25 Sun	100	—	unknown	21:50–05:05 (good, 7.25 h)	89.5° 03:45	7.24	1%	109.5°
2041-08-26 Mon	100	—	unknown	21:45–05:05 (good, 7.33 h)	89.7° 03:45	7.29	0%	118.8°
2041-08-27 Tue	100	—	unknown	21:45–05:05 (good, 7.33 h)	89.8° 03:40	7.35	2%	127.5°
2041-08-28 Wed	100	—	unknown	21:45–05:05 (good, 7.33 h)	89.8° 03:35	7.41	5%	135.3°
2041-08-29 Thu	100	—	unknown	21:40–05:10 (good, 7.5 h)	89.6° 03:30	7.46	9%	141.6°
2041-08-30 Fri	100	—	unknown	21:40–05:10 (good, 7.5 h)	89.5° 03:30	7.52	16%	145.3°
2041-08-31 Sat	100	—	unknown	21:35–05:10 (good, 7.58 h)	89.7° 03:25	7.58	23%	145.6°
2041-09-01 Sun	100	—	unknown	21:35–05:15 (good, 7.67 h)	89.8° 03:20	7.63	32%	142.1°
2041-09-02 Mon	100	—	unknown	21:35–05:15 (good, 7.67 h)	89.7° 03:15	7.69	42%	135.7°
2041-09-03 Tue	100	—	unknown	21:30–05:15 (good, 7.75 h)	89.6° 03:10	7.74	52%	127.1°
2041-09-04 Wed	100	—	unknown	21:30–05:15 (good, 7.75 h)	89.6° 03:10	7.8	63%	117.1°
2041-09-05 Thu	100	—	unknown	21:25–05:20 (good, 7.92 h)	89.8° 03:05	7.85	73%	106.1°
2041-09-06 Fri	100	—	unknown	21:25–05:20 (good, 7.92 h)	89.8° 03:00	7.91	83%	94.4°
2041-09-07 Sat	100	—	unknown	21:40–05:20 (good, 7.67 h)	89.7° 02:55	7.96	91%	82.2°
2041-09-08 Sun	100	—	unknown	23:35–05:20 (good, 5.75 h)	89.5° 02:50	8.02	96%	70.0°
2041-09-09 Mon	64	—	unknown	04:30–05:25 (good, 0.92 h)	89.7° 02:50	8.07	100%	58.1°
2041-09-10 Tue	52	—	unknown	21:15–05:25 (marginal, 8.17 h)	89.8° 02:45	8.13	100%	47.3°
2041-09-11 Wed	45	—	unknown	21:15–05:25 (marginal, 8.17 h)	89.8° 02:40	8.18	96%	38.9°
2041-09-12 Thu	49	—	unknown	21:15–05:25 (marginal, 8.17 h)	89.6° 02:35	8.23	91%	34.4°
2041-09-13 Fri	82	—	unknown	21:10–21:25 (good, 0.25 h)	89.5° 02:35	8.29	83%	35.1°
2041-09-14 Sat	86	—	unknown	21:10–00:45 (good, 3.58 h)	89.7° 02:30	8.34	74%	40.4°
2041-09-15 Sun	91	—	unknown	21:05–04:30 (good, 7.42 h)	89.8° 02:25	8.39	63%	48.3°
2041-09-16 Mon	96	—	unknown	21:05–05:30 (good, 8.42 h)	89.7° 02:20	8.44	53%	57.6°
2041-09-17 Tue	100	—	unknown	21:05–05:35 (good, 8.5 h)	89.6° 02:15	8.5	43%	67.4°
2041-09-18 Wed	100	—	unknown	21:00–05:35 (good, 8.58 h)	89.6° 02:15	8.55	33%	77.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-08-20&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.