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.

2037-05-10astronomy score per night — click a bar for that night2037-06-08

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-05-10 Sun	—	unknown	—	42.9° 15:45	5.83	18%	80.8°
2037-05-11 Mon	—	unknown	—	42.9° 15:40	5.78	11%	70.0°
2037-05-12 Tue	—	unknown	—	42.9° 15:35	5.72	6%	59.3°
2037-05-13 Wed	—	unknown	—	42.9° 15:30	5.67	2%	48.8°
2037-05-14 Thu	—	unknown	—	42.9° 15:30	5.61	0%	38.9°
2037-05-15 Fri	—	unknown	—	42.9° 15:25	5.56	1%	30.6°
2037-05-16 Sat	—	unknown	—	42.9° 15:20	5.51	3%	25.8°
2037-05-17 Sun	—	unknown	—	42.9° 15:15	5.46	8%	27.0°
2037-05-18 Mon	—	unknown	—	42.9° 15:10	5.4	15%	33.6°
2037-05-19 Tue	—	unknown	—	42.9° 15:10	5.35	24%	43.4°
2037-05-20 Wed	—	unknown	—	42.9° 15:05	5.3	34%	54.8°
2037-05-21 Thu	—	unknown	—	42.9° 15:00	5.25	45%	67.0°
2037-05-22 Fri	—	unknown	—	42.9° 14:55	5.21	56%	79.7°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-05-10&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.