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.

2037-05-11astronomy score per night — click a bar for that night2037-06-09

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-05-11 Mon	—	unknown	—	72.5° 13:50	5.78	11%	47.4°
2037-05-12 Tue	—	unknown	—	72.5° 13:45	5.72	6%	35.5°
2037-05-13 Wed	—	unknown	—	72.5° 13:45	5.67	2%	23.6°
2037-05-14 Thu	—	unknown	—	72.5° 13:40	5.61	0%	12.7°
2037-05-15 Fri	—	unknown	—	72.5° 13:35	5.56	1%	9.2°
2037-05-16 Sat	—	unknown	—	72.5° 13:30	5.51	3%	18.6°
2037-05-17 Sun	—	unknown	—	72.5° 13:30	5.46	8%	31.1°
2037-05-18 Mon	—	unknown	—	72.5° 13:25	5.4	15%	44.3°
2037-05-19 Tue	—	unknown	—	72.5° 13:20	5.35	24%	57.8°
2037-05-20 Wed	—	unknown	—	72.5° 13:15	5.3	34%	71.5°
2037-05-21 Thu	—	unknown	—	72.5° 13:10	5.25	45%	85.4°
2037-05-22 Fri	—	unknown	—	72.5° 13:10	5.21	56%	99.4°
2037-05-23 Sat	—	unknown	—	72.5° 13:05	5.16	68%	113.4°
2037-05-24 Sun	—	unknown	—	72.5° 13:00	5.11	78%	127.5°
2037-05-25 Mon	—	unknown	—	72.5° 12:55	5.07	87%	141.5°
2037-05-26 Tue	—	unknown	—	72.5° 12:50	5.02	93%	155.1°
2037-05-27 Wed	—	unknown	—	72.5° 12:50	4.98	98%	167.4°
2037-05-28 Thu	—	unknown	—	72.5° 12:45	4.94	100%	170.4°
2037-05-29 Fri	—	unknown	—	72.5° 12:40	4.9	99%	160.0°
2037-05-30 Sat	—	unknown	—	72.5° 12:35	4.86	96%	147.5°
2037-05-31 Sun	—	unknown	—	72.5° 12:35	4.82	92%	134.9°
2037-06-01 Mon	—	unknown	—	72.5° 12:30	4.78	85%	122.5°
2037-06-02 Tue	—	unknown	—	72.5° 12:25	4.75	77%	110.3°
2037-06-03 Wed	—	unknown	—	72.5° 12:20	4.72	69%	98.3°
2037-06-04 Thu	—	unknown	—	72.5° 12:15	4.68	60%	86.5°
2037-06-05 Fri	—	unknown	—	72.5° 12:15	4.65	50%	74.7°
2037-06-06 Sat	—	unknown	—	72.5° 12:10	4.62	41%	63.0°
2037-06-07 Sun	—	unknown	—	72.5° 12:05	4.6	32%	51.3°
2037-06-08 Mon	—	unknown	—	72.5° 12:00	4.57	23%	39.5°
2037-06-09 Tue	—	unknown	—	72.5° 11:55	4.55	15%	27.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-05-11&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.