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.

2027-08-27astronomy score per night — click a bar for that night2027-09-25

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-08-27 Fri	—	unknown	—	50.2° 15:30	7.32	20%	84.3°
2027-08-28 Sat	—	unknown	—	50.2° 15:25	7.37	11%	69.8°
2027-08-29 Sun	—	unknown	—	50.2° 15:20	7.43	5%	55.0°
2027-08-30 Mon	—	unknown	—	50.2° 15:20	7.49	1%	40.3°
2027-08-31 Tue	—	unknown	—	50.2° 15:15	7.54	0%	25.9°
2027-09-01 Wed	—	unknown	—	50.2° 15:10	7.6	2%	13.1°
2027-09-02 Thu	—	unknown	—	50.2° 15:05	7.65	7%	10.3°
2027-09-03 Fri	—	unknown	—	50.2° 15:00	7.71	14%	21.1°
2027-09-04 Sat	—	unknown	—	50.2° 15:00	7.76	22%	33.9°
2027-09-05 Sun	—	unknown	—	50.2° 14:55	7.82	32%	46.7°
2027-09-06 Mon	—	unknown	—	50.2° 14:50	7.87	42%	59.2°
2027-09-07 Tue	—	unknown	—	50.2° 14:45	7.93	52%	71.5°
2027-09-08 Wed	—	unknown	—	50.2° 14:40	7.98	61%	83.5°
2027-09-09 Thu	—	unknown	—	50.2° 14:40	8.04	70%	95.3°
2027-09-10 Fri	—	unknown	—	50.2° 14:35	8.09	79%	107.0°
2027-09-11 Sat	—	unknown	—	50.2° 14:30	8.15	86%	118.7°
2027-09-12 Sun	—	unknown	—	50.2° 14:25	8.2	92%	130.3°
2027-09-13 Mon	—	unknown	—	50.2° 14:25	8.25	96%	141.9°
2027-09-14 Tue	—	unknown	—	50.2° 14:20	8.31	99%	153.4°
2027-09-15 Wed	—	unknown	—	50.2° 14:15	8.36	100%	164.3°
2027-09-16 Thu	—	unknown	—	50.2° 14:10	8.41	99%	171.0°
2027-09-17 Fri	—	unknown	—	50.2° 14:05	8.46	96%	165.1°
2027-09-18 Sat	—	unknown	—	50.2° 14:05	8.52	91%	153.9°
2027-09-19 Sun	—	unknown	—	50.2° 14:00	8.57	84%	141.6°
2027-09-20 Mon	—	unknown	—	50.2° 13:55	8.62	76%	128.8°
2027-09-21 Tue	—	unknown	—	50.2° 13:50	8.67	66%	115.7°
2027-09-22 Wed	—	unknown	—	50.2° 13:45	8.72	56%	102.3°
2027-09-23 Thu	—	unknown	—	50.2° 13:45	8.77	44%	88.6°
2027-09-24 Fri	—	unknown	—	50.2° 13:40	8.82	33%	74.6°
2027-09-25 Sat	—	unknown	—	50.2° 13:35	8.87	23%	60.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-27&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.