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.

2031-06-20astronomy score per night — click a bar for that night2031-07-19

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2031-07-04 Fri	—	unknown	—	42.9° 12:10	4.6	100%	147.6°
2031-07-05 Sat	—	unknown	—	42.9° 12:05	4.63	98%	137.4°
2031-07-06 Sun	—	unknown	—	42.9° 12:00	4.66	93%	125.3°
2031-07-07 Mon	—	unknown	—	42.9° 11:55	4.69	86%	112.6°
2031-07-08 Tue	—	unknown	—	42.9° 11:50	4.72	77%	99.9°
2031-07-09 Wed	—	unknown	—	42.9° 11:45	4.76	66%	87.5°
2031-07-10 Thu	—	unknown	—	42.9° 11:40	4.79	56%	75.5°
2031-07-11 Fri	—	unknown	—	42.9° 11:40	4.83	45%	64.0°
2031-07-12 Sat	—	unknown	—	42.9° 11:35	4.87	36%	53.2°
2031-07-13 Sun	—	unknown	—	42.9° 11:30	4.91	26%	43.3°
2031-07-14 Mon	—	unknown	—	42.9° 11:25	4.95	18%	34.8°
2031-07-15 Tue	—	unknown	—	42.9° 11:20	4.99	12%	28.6°
2031-07-16 Wed	—	unknown	—	42.9° 11:20	5.03	6%	26.3°
2031-07-17 Thu	—	unknown	—	42.9° 11:15	5.08	2%	28.8°
2031-07-18 Fri	—	unknown	—	42.9° 11:10	5.12	0%	35.0°
2031-07-19 Sat	—	unknown	—	42.9° 11:05	5.17	0%	43.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-06-20&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.