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: 11-21 (100), 11-22 (100), 11-23 (100), 11-24 (100), 11-25 (100) — by astronomy; check the weather when the night is within four days.

2040-11-16astronomy score per night — click a bar for that night2040-12-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-11-16 Fri	39	—	unknown	18:40–03:30 (marginal, 8.83 h)	89.8° 21:20	11.0	96%	35.6°
2040-11-17 Sat	39	—	unknown	18:40–00:35 (marginal, 5.92 h)	89.7° 21:15	11.03	99%	38.1°
2040-11-18 Sun	47	—	unknown	18:35–01:20 (marginal, 6.75 h)	89.5° 21:10	11.06	100%	43.9°
2040-11-19 Mon	62	—	unknown	18:35–18:55 (good, 0.33 h)	89.6° 21:10	11.08	99%	51.7°
2040-11-20 Tue	70	—	unknown	18:35–20:45 (good, 2.17 h)	89.8° 21:05	11.11	95%	60.5°
2040-11-21 Wed	100	—	unknown	18:35–23:20 (good, 4.75 h)	89.8° 21:00	11.13	90%	69.9°
2040-11-22 Thu	100	—	unknown	18:35–00:55 (good, 6.33 h)	89.6° 20:55	11.16	84%	79.5°
2040-11-23 Fri	100	—	unknown	18:35–02:15 (good, 7.67 h)	89.5° 20:55	11.18	76%	89.2°
2040-11-24 Sat	100	—	unknown	18:35–02:35 (good, 8.0 h)	89.7° 20:50	11.2	68%	98.8°
2040-11-25 Sun	100	—	unknown	18:35–02:40 (good, 8.08 h)	89.8° 20:45	11.23	59%	108.3°
2040-11-26 Mon	100	—	unknown	18:35–02:45 (good, 8.17 h)	89.7° 20:40	11.25	50%	117.5°
2040-11-27 Tue	100	—	unknown	18:35–02:40 (good, 8.08 h)	89.6° 20:35	11.27	40%	126.2°
2040-11-28 Wed	100	—	unknown	18:35–02:40 (good, 8.08 h)	89.6° 20:35	11.29	31%	134.1°
2040-11-29 Thu	100	—	unknown	18:35–02:40 (good, 8.08 h)	89.7° 20:30	11.31	22%	140.5°
2040-11-30 Fri	100	—	unknown	18:35–02:35 (good, 8.0 h)	89.8° 20:25	11.32	14%	144.0°
2040-12-01 Sat	100	—	unknown	18:35–02:30 (good, 7.92 h)	89.7° 20:20	11.34	7%	143.6°
2040-12-02 Sun	100	—	unknown	18:35–02:25 (good, 7.83 h)	89.5° 20:15	11.36	2%	139.0°
2040-12-03 Mon	100	—	unknown	18:35–02:20 (good, 7.75 h)	89.6° 20:15	11.37	0%	131.1°
2040-12-04 Tue	100	—	unknown	18:35–02:20 (good, 7.75 h)	89.8° 20:10	11.39	1%	121.1°
2040-12-05 Wed	100	—	unknown	18:35–02:15 (good, 7.67 h)	89.8° 20:05	11.4	4%	109.9°
2040-12-06 Thu	100	—	unknown	18:35–02:10 (good, 7.58 h)	89.7° 20:00	11.42	10%	98.1°
2040-12-07 Fri	100	—	unknown	18:35–02:05 (good, 7.5 h)	89.5° 20:00	11.43	18%	86.1°
2040-12-08 Sat	100	—	unknown	18:35–02:05 (good, 7.5 h)	89.7° 19:55	11.44	27%	74.4°
2040-12-09 Sun	100	—	unknown	18:35–02:00 (good, 7.42 h)	89.8° 19:50	11.45	38%	63.3°
2040-12-10 Mon	90	—	unknown	18:35–01:55 (good, 7.33 h)	89.8° 19:45	11.46	49%	53.1°
2040-12-11 Tue	82	—	unknown	18:35–01:50 (good, 7.25 h)	89.6° 19:40	11.47	60%	44.4°
2040-12-12 Wed	57	—	unknown	18:35–02:20 (marginal, 7.75 h)	89.6° 19:40	11.48	71%	38.3°
2040-12-13 Thu	42	—	unknown	18:35–02:05 (marginal, 7.5 h)	89.7° 19:35	11.48	80%	35.6°
2040-12-14 Fri	34	—	unknown	18:35–01:40 (marginal, 7.08 h)	89.8° 19:30	11.49	88%	37.0°
2040-12-15 Sat	32	—	unknown	18:35–01:20 (marginal, 6.75 h)	89.7° 19:25	11.49	94%	42.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-11-16&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.