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.

2041-06-13astronomy score per night — click a bar for that night2041-07-12

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-06-13 Thu	—	unknown	—	42.9° 13:30	4.47	100%	148.0°
2041-06-14 Fri	—	unknown	—	42.9° 13:25	4.46	100%	146.8°
2041-06-15 Sat	—	unknown	—	42.9° 13:20	4.45	97%	140.7°
2041-06-16 Sun	—	unknown	—	42.9° 13:20	4.44	92%	131.4°
2041-06-17 Mon	—	unknown	—	42.9° 13:15	4.43	84%	120.4°
2041-06-18 Tue	—	unknown	—	42.9° 13:10	4.43	74%	108.6°
2041-06-19 Wed	—	unknown	—	42.9° 13:05	4.42	64%	96.5°
2041-06-20 Thu	—	unknown	—	42.9° 13:00	4.42	52%	84.4°
2041-06-21 Fri	—	unknown	—	42.9° 13:00	4.42	41%	72.6°
2041-06-22 Sat	—	unknown	—	42.9° 12:55	4.43	30%	61.4°
2041-06-23 Sun	—	unknown	—	42.9° 12:50	4.43	21%	50.9°
2041-06-24 Mon	—	unknown	—	42.9° 12:45	4.44	13%	41.8°
2041-06-25 Tue	—	unknown	—	42.9° 12:45	4.45	7%	35.1°
2041-06-26 Wed	—	unknown	—	42.9° 12:40	4.46	2%	31.9°
2041-06-27 Thu	—	unknown	—	42.9° 12:35	4.47	0%	33.1°
2041-06-28 Fri	—	unknown	—	42.9° 12:30	4.49	0%	38.2°
2041-06-29 Sat	—	unknown	—	42.9° 12:25	4.5	2%	45.6°
2041-06-30 Sun	—	unknown	—	42.9° 12:25	4.52	6%	54.4°
2041-07-01 Mon	—	unknown	—	42.9° 12:20	4.55	11%	63.8°
2041-07-02 Tue	—	unknown	—	42.9° 12:15	4.57	18%	73.6°
2041-07-03 Wed	—	unknown	—	42.9° 12:10	4.59	26%	83.5°
2041-07-04 Thu	—	unknown	—	42.9° 12:05	4.62	34%	93.6°
2041-07-05 Fri	—	unknown	—	42.9° 12:00	4.65	44%	103.7°
2041-07-06 Sat	—	unknown	—	42.9° 12:00	4.68	53%	113.8°
2041-07-07 Sun	—	unknown	—	42.9° 11:50	4.71	63%	123.7°
2041-07-08 Mon	—	unknown	—	42.9° 11:50	4.74	73%	133.0°
2041-07-09 Tue	—	unknown	—	42.9° 11:45	4.78	82%	141.2°
2041-07-10 Wed	—	unknown	—	42.9° 11:40	4.81	89%	146.8°
2041-07-11 Thu	—	unknown	—	42.9° 11:35	4.85	95%	147.9°
2041-07-12 Fri	—	unknown	—	42.9° 11:30	4.89	99%	143.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-06-13&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.