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.

2027-06-12astronomy score per night — click a bar for that night2027-07-11

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-06-12 Sat	—	unknown	—	42.9° 13:35	4.5	66%	102.9°
2027-06-13 Sun	—	unknown	—	42.9° 13:30	4.48	76%	113.8°
2027-06-14 Mon	—	unknown	—	42.9° 13:30	4.47	84%	124.0°
2027-06-15 Tue	—	unknown	—	42.9° 13:25	4.45	91%	133.2°
2027-06-16 Wed	—	unknown	—	42.9° 13:20	4.44	96%	140.8°
2027-06-17 Thu	—	unknown	—	42.9° 13:15	4.44	99%	145.9°
2027-06-18 Fri	—	unknown	—	42.9° 13:10	4.43	100%	147.5°
2027-06-19 Sat	—	unknown	—	42.9° 13:10	4.42	99%	145.2°
2027-06-20 Sun	—	unknown	—	42.9° 13:05	4.42	97%	139.7°
2027-06-21 Mon	—	unknown	—	42.9° 13:00	4.42	92%	132.3°
2027-06-22 Tue	—	unknown	—	42.9° 12:55	4.42	87%	123.7°
2027-06-23 Wed	—	unknown	—	42.9° 12:50	4.43	80%	114.3°
2027-06-24 Thu	—	unknown	—	42.9° 12:50	4.43	72%	104.5°
2027-06-25 Fri	—	unknown	—	42.9° 12:45	4.44	62%	94.4°
2027-06-26 Sat	—	unknown	—	42.9° 12:40	4.45	53%	84.1°
2027-06-27 Sun	—	unknown	—	42.9° 12:35	4.46	43%	73.5°
2027-06-28 Mon	—	unknown	—	42.9° 12:35	4.48	32%	63.0°
2027-06-29 Tue	—	unknown	—	42.9° 12:30	4.49	23%	52.7°
2027-06-30 Wed	—	unknown	—	42.9° 12:25	4.51	14%	43.2°
2027-07-01 Thu	—	unknown	—	42.9° 12:20	4.53	7%	35.8°
2027-07-02 Fri	—	unknown	—	42.9° 12:15	4.55	2%	32.6°
2027-07-03 Sat	—	unknown	—	42.9° 12:15	4.58	0%	35.1°
2027-07-04 Sun	—	unknown	—	42.9° 12:10	4.6	1%	42.5°
2027-07-05 Mon	—	unknown	—	42.9° 12:05	4.63	5%	52.8°
2027-07-06 Tue	—	unknown	—	42.9° 12:00	4.66	11%	64.4°
2027-07-07 Wed	—	unknown	—	42.9° 11:55	4.69	20%	76.4°
2027-07-08 Thu	—	unknown	—	42.9° 11:50	4.72	30%	88.4°
2027-07-09 Fri	—	unknown	—	42.9° 11:45	4.76	41%	100.0°
2027-07-10 Sat	—	unknown	—	42.9° 11:40	4.79	52%	111.2°
2027-07-11 Sun	—	unknown	—	42.9° 11:40	4.83	62%	121.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-06-12&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.