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.

2037-05-23astronomy score per night — click a bar for that night2037-06-21

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-05-23 Sat	—	unknown	—	42.9° 14:50	5.16	68%	92.5°
2037-05-24 Sun	—	unknown	—	42.9° 14:50	5.11	78%	105.4°
2037-05-25 Mon	—	unknown	—	42.9° 14:45	5.07	87%	118.0°
2037-05-26 Tue	—	unknown	—	42.9° 14:40	5.02	93%	130.2°
2037-05-27 Wed	—	unknown	—	42.9° 14:35	4.98	98%	141.2°
2037-05-28 Thu	—	unknown	—	42.9° 14:35	4.94	100%	150.0°
2037-05-29 Fri	—	unknown	—	42.9° 14:30	4.9	99%	154.3°
2037-05-30 Sat	—	unknown	—	42.9° 14:25	4.86	96%	152.5°
2037-05-31 Sun	—	unknown	—	42.9° 14:20	4.82	92%	145.8°
2037-06-01 Mon	—	unknown	—	42.9° 14:15	4.78	85%	136.7°
2037-06-02 Tue	—	unknown	—	42.9° 14:15	4.75	77%	126.6°
2037-06-03 Wed	—	unknown	—	42.9° 14:10	4.72	69%	116.2°
2037-06-04 Thu	—	unknown	—	42.9° 14:05	4.68	60%	105.6°
2037-06-05 Fri	—	unknown	—	42.9° 14:00	4.65	50%	94.9°
2037-06-06 Sat	—	unknown	—	42.9° 13:55	4.62	41%	84.2°
2037-06-07 Sun	—	unknown	—	42.9° 13:55	4.6	32%	73.5°
2037-06-08 Mon	—	unknown	—	42.9° 13:50	4.57	23%	62.8°
2037-06-09 Tue	—	unknown	—	42.9° 13:45	4.55	15%	52.2°
2037-06-10 Wed	—	unknown	—	42.9° 13:40	4.53	9%	42.1°
2037-06-11 Thu	—	unknown	—	42.9° 13:40	4.51	4%	33.1°
2037-06-12 Fri	—	unknown	—	42.9° 13:35	4.49	1%	26.8°
2037-06-13 Sat	—	unknown	—	42.9° 13:30	4.47	0%	26.0°
2037-06-14 Sun	—	unknown	—	42.9° 13:25	4.46	2%	31.3°
2037-06-15 Mon	—	unknown	—	42.9° 13:20	4.45	6%	40.7°
2037-06-16 Tue	—	unknown	—	42.9° 13:20	4.44	13%	52.0°
2037-06-17 Wed	—	unknown	—	42.9° 13:15	4.43	21%	64.2°
2037-06-18 Thu	—	unknown	—	42.9° 13:10	4.43	32%	76.9°
2037-06-19 Fri	—	unknown	—	42.9° 13:05	4.42	43%	89.8°
2037-06-20 Sat	—	unknown	—	42.9° 13:00	4.42	54%	102.5°
2037-06-21 Sun	—	unknown	—	42.9° 13:00	4.42	65%	115.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-05-23&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.