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.

2041-04-24astronomy score per night — click a bar for that night2041-05-23

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-04-24 Wed	—	unknown	—	79.2° 12:45	6.75	36%	75.1°
2041-04-25 Thu	—	unknown	—	79.2° 12:40	6.69	26%	61.8°
2041-04-26 Fri	—	unknown	—	79.2° 12:40	6.63	16%	48.8°
2041-04-27 Sat	—	unknown	—	79.2° 12:35	6.57	8%	36.5°
2041-04-28 Sun	—	unknown	—	79.2° 12:30	6.52	3%	26.1°
2041-04-29 Mon	—	unknown	—	79.2° 12:25	6.46	0%	20.5°
2041-04-30 Tue	—	unknown	—	79.2° 12:20	6.4	0%	23.2°
2041-05-01 Wed	—	unknown	—	79.2° 12:20	6.34	2%	31.9°
2041-05-02 Thu	—	unknown	—	79.2° 12:15	6.28	7%	42.6°
2041-05-03 Fri	—	unknown	—	79.2° 12:10	6.23	13%	54.0°
2041-05-04 Sat	—	unknown	—	79.2° 12:05	6.17	21%	65.5°
2041-05-05 Sun	—	unknown	—	79.2° 12:00	6.11	29%	77.0°
2041-05-06 Mon	—	unknown	—	79.2° 11:55	6.05	38%	88.3°
2041-05-07 Tue	—	unknown	—	79.2° 11:50	6.0	48%	99.4°
2041-05-08 Wed	—	unknown	—	79.2° 11:45	5.94	57%	110.5°
2041-05-09 Thu	—	unknown	—	79.2° 11:45	5.89	66%	121.4°
2041-05-10 Fri	—	unknown	—	79.2° 11:40	5.83	75%	132.1°
2041-05-11 Sat	—	unknown	—	79.2° 11:35	5.77	83%	142.5°
2041-05-12 Sun	—	unknown	—	79.2° 11:30	5.72	90%	151.9°
2041-05-13 Mon	—	unknown	—	79.2° 11:25	5.67	95%	158.4°
2041-05-14 Tue	—	unknown	—	79.2° 11:25	5.61	99%	158.9°
2041-05-15 Wed	—	unknown	—	79.2° 11:20	5.56	100%	152.4°
2041-05-16 Thu	—	unknown	—	79.2° 11:15	5.51	99%	142.2°
2041-05-17 Fri	—	unknown	—	79.2° 11:10	5.45	96%	130.4°
2041-05-18 Sat	—	unknown	—	79.2° 11:10	5.4	90%	117.7°
2041-05-19 Sun	—	unknown	—	79.2° 11:05	5.35	82%	104.6°
2041-05-20 Mon	—	unknown	—	79.2° 11:00	5.3	72%	91.4°
2041-05-21 Tue	—	unknown	—	79.2° 10:55	5.25	62%	78.1°
2041-05-22 Wed	—	unknown	—	79.2° 10:50	5.2	50%	64.9°
2041-05-23 Thu	—	unknown	—	79.2° 10:50	5.16	39%	52.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-24&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.