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.

2031-06-04astronomy score per night — click a bar for that night2031-07-03

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-06-04 Wed	—	unknown	—	42.9° 14:05	4.7	100%	147.8°
2031-06-05 Thu	—	unknown	—	42.9° 14:05	4.67	100%	153.3°
2031-06-06 Fri	—	unknown	—	42.9° 14:00	4.64	97%	151.6°
2031-06-07 Sat	—	unknown	—	42.9° 13:55	4.61	91%	143.7°
2031-06-08 Sun	—	unknown	—	42.9° 13:50	4.59	83%	132.7°
2031-06-09 Mon	—	unknown	—	42.9° 13:45	4.56	74%	120.7°
2031-06-10 Tue	—	unknown	—	42.9° 13:45	4.54	63%	108.4°
2031-06-11 Wed	—	unknown	—	42.9° 13:40	4.52	52%	96.1°
2031-06-12 Thu	—	unknown	—	42.9° 13:35	4.5	41%	84.2°
2031-06-13 Fri	—	unknown	—	42.9° 13:30	4.48	31%	72.6°
2031-06-14 Sat	—	unknown	—	42.9° 13:30	4.47	22%	61.4°
2031-06-15 Sun	—	unknown	—	42.9° 13:25	4.46	14%	50.9°
2031-06-16 Mon	—	unknown	—	42.9° 13:20	4.44	8%	41.3°
2031-06-17 Tue	—	unknown	—	42.9° 13:15	4.44	4%	33.1°
2031-06-18 Wed	—	unknown	—	42.9° 13:10	4.43	1%	27.7°
2031-06-19 Thu	—	unknown	—	42.9° 13:10	4.43	0%	26.5°
2031-06-20 Fri	—	unknown	—	42.9° 13:05	4.42	1%	30.0°
2031-06-21 Sat	—	unknown	—	42.9° 13:00	4.42	4%	36.9°
2031-06-22 Sun	—	unknown	—	42.9° 12:55	4.42	8%	45.6°
2031-06-23 Mon	—	unknown	—	42.9° 12:50	4.43	14%	55.3°
2031-06-24 Tue	—	unknown	—	42.9° 12:50	4.43	21%	65.5°
2031-06-25 Wed	—	unknown	—	42.9° 12:45	4.44	30%	76.3°
2031-06-26 Thu	—	unknown	—	42.9° 12:40	4.45	39%	87.3°
2031-06-27 Fri	—	unknown	—	42.9° 12:35	4.46	49%	98.6°
2031-06-28 Sat	—	unknown	—	42.9° 12:35	4.48	60%	110.2°
2031-06-29 Sun	—	unknown	—	42.9° 12:30	4.5	70%	121.9°
2031-06-30 Mon	—	unknown	—	42.9° 12:25	4.51	80%	133.3°
2031-07-01 Tue	—	unknown	—	42.9° 12:20	4.53	88%	143.9°
2031-07-02 Wed	—	unknown	—	42.9° 12:15	4.56	95%	151.7°
2031-07-03 Thu	—	unknown	—	42.9° 12:15	4.58	99%	153.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-06-04&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.