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: 08-12 (100), 08-13 (100), 08-14 (100), 08-15 (100), 08-16 (100) — by astronomy; check the weather when the night is within four days.

2031-08-10astronomy score per night — click a bar for that night2031-09-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-08-10 Sun	90	—	unknown	22:45–04:40 (good, 5.92 h)	89.6° 04:50	6.34	41%	44.4°
2031-08-11 Mon	95	—	unknown	22:40–04:40 (good, 6.0 h)	89.7° 04:45	6.4	32%	53.1°
2031-08-12 Tue	100	—	unknown	22:35–04:45 (good, 6.17 h)	89.7° 04:40	6.46	23%	62.6°
2031-08-13 Wed	100	—	unknown	22:35–04:45 (good, 6.17 h)	89.6° 04:35	6.52	16%	72.4°
2031-08-14 Thu	100	—	unknown	22:30–04:45 (good, 6.25 h)	89.5° 04:30	6.57	10%	82.5°
2031-08-15 Fri	100	—	unknown	22:25–04:45 (good, 6.33 h)	89.6° 04:30	6.63	5%	92.6°
2031-08-16 Sat	100	—	unknown	22:20–04:50 (good, 6.5 h)	89.7° 04:25	6.69	2%	102.7°
2031-08-17 Sun	100	—	unknown	22:15–04:50 (good, 6.58 h)	89.7° 04:20	6.75	0%	112.8°
2031-08-18 Mon	100	—	unknown	22:15–04:50 (good, 6.58 h)	89.6° 04:15	6.8	1%	122.7°
2031-08-19 Tue	100	—	unknown	22:10–04:55 (good, 6.75 h)	89.5° 04:15	6.86	3%	132.0°
2031-08-20 Wed	100	—	unknown	22:05–04:55 (good, 6.83 h)	89.7° 04:10	6.92	7%	140.2°
2031-08-21 Thu	100	—	unknown	22:00–04:55 (good, 6.92 h)	89.7° 04:05	6.98	14%	146.3°
2031-08-22 Fri	100	—	unknown	21:55–05:00 (good, 7.08 h)	89.7° 04:00	7.03	21%	148.9°
2031-08-23 Sat	100	—	unknown	21:55–05:00 (good, 7.08 h)	89.5° 03:55	7.09	30%	146.7°
2031-08-24 Sun	100	—	unknown	21:55–05:00 (good, 7.08 h)	89.6° 03:55	7.15	41%	140.4°
2031-08-25 Mon	100	—	unknown	21:50–05:00 (good, 7.17 h)	89.7° 03:50	7.2	52%	131.3°
2031-08-26 Tue	100	—	unknown	21:50–05:05 (good, 7.25 h)	89.7° 03:45	7.26	63%	120.5°
2031-08-27 Wed	100	—	unknown	21:50–05:05 (good, 7.25 h)	89.6° 03:40	7.32	74%	108.8°
2031-08-28 Thu	100	—	unknown	22:00–05:05 (good, 7.08 h)	89.5° 03:35	7.37	83%	96.4°
2031-08-29 Fri	100	—	unknown	22:45–05:10 (good, 6.42 h)	89.6° 03:35	7.43	91%	83.8°
2031-08-30 Sat	74	—	unknown	00:35–05:10 (good, 4.58 h)	89.7° 03:30	7.49	97%	71.2°
2031-08-31 Sun	62	—	unknown	04:40–05:10 (good, 0.5 h)	89.7° 03:25	7.54	100%	59.0°
2031-09-01 Mon	46	—	unknown	21:35–05:10 (marginal, 7.58 h)	89.6° 03:20	7.6	99%	47.9°
2031-09-02 Tue	36	—	unknown	21:35–05:15 (marginal, 7.67 h)	89.5° 03:20	7.66	97%	38.6°
2031-09-03 Wed	39	—	unknown	21:30–05:15 (marginal, 7.75 h)	89.7° 03:15	7.71	92%	32.6°
2031-09-04 Thu	49	—	unknown	21:30–05:15 (marginal, 7.75 h)	89.7° 03:10	7.77	84%	31.4°
2031-09-05 Fri	83	—	unknown	21:30–22:00 (good, 0.5 h)	89.7° 03:05	7.82	76%	35.0°
2031-09-06 Sat	88	—	unknown	21:25–02:35 (good, 5.17 h)	89.5° 03:00	7.88	67%	41.9°
2031-09-07 Sun	93	—	unknown	21:25–05:20 (good, 7.92 h)	89.6° 03:00	7.93	57%	50.4°
2031-09-08 Mon	99	—	unknown	21:20–05:20 (good, 8.0 h)	89.7° 02:55	7.99	48%	59.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-08-10&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.