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.

2045-04-27astronomy score per night — click a bar for that night2045-05-26

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-04-27 Thu	—	unknown	—	79.2° 12:35	6.57	87%	139.5°
2045-04-28 Fri	—	unknown	—	79.2° 12:30	6.51	94%	151.9°
2045-04-29 Sat	—	unknown	—	79.2° 12:25	6.46	98%	162.0°
2045-04-30 Sun	—	unknown	—	79.2° 12:25	6.4	100%	164.8°
2045-05-01 Mon	—	unknown	—	79.2° 12:20	6.34	99%	157.9°
2045-05-02 Tue	—	unknown	—	79.2° 12:15	6.28	97%	147.2°
2045-05-03 Wed	—	unknown	—	79.2° 12:10	6.22	92%	135.6°
2045-05-04 Thu	—	unknown	—	79.2° 12:05	6.17	86%	123.9°
2045-05-05 Fri	—	unknown	—	79.2° 12:00	6.11	78%	112.2°
2045-05-06 Sat	—	unknown	—	79.2° 11:55	6.05	70%	100.6°
2045-05-07 Sun	—	unknown	—	79.2° 11:50	6.0	61%	89.1°
2045-05-08 Mon	—	unknown	—	79.2° 11:45	5.94	52%	77.7°
2045-05-09 Tue	—	unknown	—	79.2° 11:45	5.88	42%	66.2°
2045-05-10 Wed	—	unknown	—	79.2° 11:40	5.83	33%	54.8°
2045-05-11 Thu	—	unknown	—	79.2° 11:35	5.77	24%	43.3°
2045-05-12 Fri	—	unknown	—	79.2° 11:30	5.72	16%	32.0°
2045-05-13 Sat	—	unknown	—	79.2° 11:25	5.66	10%	21.6°
2045-05-14 Sun	—	unknown	—	79.2° 11:25	5.61	4%	15.0°
2045-05-15 Mon	—	unknown	—	79.2° 11:20	5.56	1%	18.3°
2045-05-16 Tue	—	unknown	—	79.2° 11:15	5.5	0%	28.5°
2045-05-17 Wed	—	unknown	—	79.2° 11:10	5.45	2%	41.1°
2045-05-18 Thu	—	unknown	—	79.2° 11:10	5.4	6%	54.5°
2045-05-19 Fri	—	unknown	—	79.2° 11:05	5.35	13%	68.3°
2045-05-20 Sat	—	unknown	—	79.2° 11:00	5.3	22%	82.2°
2045-05-21 Sun	—	unknown	—	79.2° 10:55	5.25	32%	96.1°
2045-05-22 Mon	—	unknown	—	79.2° 10:50	5.2	43%	109.8°
2045-05-23 Tue	—	unknown	—	79.2° 10:50	5.16	55%	123.3°
2045-05-24 Wed	—	unknown	—	79.2° 10:45	5.11	66%	136.5°
2045-05-25 Thu	—	unknown	—	79.2° 10:40	5.06	76%	148.9°
2045-05-26 Fri	—	unknown	—	79.2° 10:35	5.02	84%	159.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-04-27&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.