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: 08-20 (100), 08-31 (100), 09-01 (100), 09-02 (100), 09-03 (100) — by astronomy; check the weather when the night is within four days.

2040-08-20astronomy score per night — click a bar for that night2040-09-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-08-20 Mon	100	—	unknown	23:05–04:55 (good, 5.83 h)	89.7° 04:05	6.96	97%	84.1°
2040-08-21 Tue	70	—	unknown	00:40–04:55 (good, 4.25 h)	89.5° 04:00	7.02	100%	72.1°
2040-08-22 Wed	60	—	unknown	21:55–05:35 (marginal, 7.67 h)	89.6° 04:00	7.08	99%	60.6°
2040-08-23 Thu	48	—	unknown	21:50–05:00 (marginal, 7.17 h)	89.8° 03:55	7.14	96%	50.3°
2040-08-24 Fri	48	—	unknown	21:50–05:00 (marginal, 7.17 h)	89.8° 03:50	7.19	91%	42.1°
2040-08-25 Sat	75	—	unknown	21:50–22:10 (good, 0.33 h)	89.7° 03:45	7.25	84%	37.0°
2040-08-26 Sun	82	—	unknown	21:45–22:35 (good, 0.83 h)	89.5° 03:45	7.31	75%	36.0°
2040-08-27 Mon	86	—	unknown	21:45–02:50 (good, 5.08 h)	89.7° 03:40	7.36	65%	39.0°
2040-08-28 Tue	90	—	unknown	21:40–05:05 (good, 7.42 h)	89.8° 03:35	7.42	55%	44.9°
2040-08-29 Wed	94	—	unknown	21:40–05:10 (good, 7.5 h)	89.8° 03:30	7.48	46%	52.6°
2040-08-30 Thu	99	—	unknown	21:40–05:10 (good, 7.5 h)	89.6° 03:25	7.53	36%	61.2°
2040-08-31 Fri	100	—	unknown	21:35–05:10 (good, 7.58 h)	89.6° 03:25	7.59	27%	70.3°
2040-09-01 Sat	100	—	unknown	21:35–05:15 (good, 7.67 h)	89.7° 03:20	7.65	19%	79.7°
2040-09-02 Sun	100	—	unknown	21:30–05:15 (good, 7.75 h)	89.8° 03:15	7.7	12%	89.3°
2040-09-03 Mon	100	—	unknown	21:30–05:15 (good, 7.75 h)	89.7° 03:10	7.76	7%	98.9°
2040-09-04 Tue	100	—	unknown	21:30–05:15 (good, 7.75 h)	89.6° 03:05	7.81	3%	108.5°
2040-09-05 Wed	100	—	unknown	21:25–05:20 (good, 7.92 h)	89.6° 03:05	7.87	1%	117.8°
2040-09-06 Thu	100	—	unknown	21:25–05:20 (good, 7.92 h)	89.8° 03:00	7.92	0%	126.6°
2040-09-07 Fri	100	—	unknown	21:20–05:20 (good, 8.0 h)	89.8° 02:55	7.98	2%	134.6°
2040-09-08 Sat	100	—	unknown	21:20–05:20 (good, 8.0 h)	89.7° 02:50	8.03	5%	140.7°
2040-09-09 Sun	100	—	unknown	21:20–05:25 (good, 8.08 h)	89.5° 02:45	8.08	11%	144.0°
2040-09-10 Mon	100	—	unknown	21:15–05:25 (good, 8.17 h)	89.7° 02:45	8.14	18%	143.5°
2040-09-11 Tue	100	—	unknown	21:15–05:25 (good, 8.17 h)	89.8° 02:40	8.19	27%	139.1°
2040-09-12 Wed	100	—	unknown	21:10–05:25 (good, 8.25 h)	89.8° 02:35	8.25	37%	131.7°
2040-09-13 Thu	100	—	unknown	21:10–05:30 (good, 8.33 h)	89.6° 02:30	8.3	48%	122.3°
2040-09-14 Fri	100	—	unknown	21:10–05:30 (good, 8.33 h)	89.5° 02:30	8.35	60%	111.8°
2040-09-15 Sat	100	—	unknown	21:05–05:30 (good, 8.42 h)	89.7° 02:25	8.4	70%	100.5°
2040-09-16 Sun	100	—	unknown	21:05–05:30 (good, 8.42 h)	89.8° 02:20	8.46	80%	88.7°
2040-09-17 Mon	100	—	unknown	21:25–05:35 (good, 8.17 h)	89.7° 02:15	8.51	89%	76.9°
2040-09-18 Tue	99	—	unknown	23:30–05:35 (good, 6.08 h)	89.6° 02:10	8.56	95%	65.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-08-20&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.