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.

2039-06-17astronomy score per night — click a bar for that night2039-07-16

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-06-17 Fri	—	unknown	—	42.9° 13:15	4.44	12%	43.8°
2039-06-18 Sat	—	unknown	—	42.9° 13:10	4.43	7%	36.0°
2039-06-19 Sun	—	unknown	—	42.9° 13:10	4.42	3%	30.5°
2039-06-20 Mon	—	unknown	—	42.9° 13:05	4.42	1%	28.6°
2039-06-21 Tue	—	unknown	—	42.9° 13:00	4.42	0%	31.1°
2039-06-22 Wed	—	unknown	—	42.9° 12:55	4.42	1%	37.1°
2039-06-23 Thu	—	unknown	—	42.9° 12:55	4.43	4%	45.3°
2039-06-24 Fri	—	unknown	—	42.9° 12:50	4.43	10%	54.8°
2039-06-25 Sat	—	unknown	—	42.9° 12:45	4.44	16%	65.2°
2039-06-26 Sun	—	unknown	—	42.9° 12:40	4.45	24%	76.1°
2039-06-27 Mon	—	unknown	—	42.9° 12:35	4.47	34%	87.4°
2039-06-28 Tue	—	unknown	—	42.9° 12:35	4.48	44%	99.0°
2039-06-29 Wed	—	unknown	—	42.9° 12:30	4.5	55%	110.7°
2039-06-30 Thu	—	unknown	—	42.9° 12:25	4.51	66%	122.5°
2039-07-01 Fri	—	unknown	—	42.9° 12:20	4.53	77%	133.8°
2039-07-02 Sat	—	unknown	—	42.9° 12:15	4.56	86%	143.7°
2039-07-03 Sun	—	unknown	—	42.9° 12:15	4.58	93%	150.2°
2039-07-04 Mon	—	unknown	—	42.9° 12:10	4.61	98%	150.7°
2039-07-05 Tue	—	unknown	—	42.9° 12:05	4.63	100%	144.7°
2039-07-06 Wed	—	unknown	—	42.9° 12:00	4.66	99%	134.9°
2039-07-07 Thu	—	unknown	—	42.9° 11:55	4.69	95%	123.4°
2039-07-08 Fri	—	unknown	—	42.9° 11:50	4.73	89%	111.5°
2039-07-09 Sat	—	unknown	—	42.9° 11:45	4.76	81%	99.6°
2039-07-10 Sun	—	unknown	—	42.9° 11:40	4.79	72%	87.9°
2039-07-11 Mon	—	unknown	—	42.9° 11:40	4.83	62%	76.7°
2039-07-12 Tue	—	unknown	—	42.9° 11:35	4.87	52%	65.9°
2039-07-13 Wed	—	unknown	—	42.9° 11:30	4.91	42%	55.7°
2039-07-14 Thu	—	unknown	—	42.9° 11:25	4.95	33%	46.3°
2039-07-15 Fri	—	unknown	—	42.9° 11:20	4.99	24%	38.0°
2039-07-16 Sat	—	unknown	—	42.9° 11:20	5.03	17%	31.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-06-17&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.