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.

2041-04-24astronomy score per night — click a bar for that night2041-05-23

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-04-24 Wed	—	unknown	—	72.5° 15:00	6.75	36%	99.0°
2041-04-25 Thu	—	unknown	—	72.5° 14:55	6.69	26%	84.7°
2041-04-26 Fri	—	unknown	—	72.5° 14:50	6.63	16%	70.3°
2041-04-27 Sat	—	unknown	—	72.5° 14:45	6.57	8%	56.0°
2041-04-28 Sun	—	unknown	—	72.5° 14:45	6.52	3%	41.7°
2041-04-29 Mon	—	unknown	—	72.5° 14:40	6.46	0%	27.6°
2041-04-30 Tue	—	unknown	—	72.5° 14:35	6.4	0%	13.8°
2041-05-01 Wed	—	unknown	—	72.5° 14:30	6.34	2%	2.8°
2041-05-02 Thu	—	unknown	—	72.5° 14:25	6.28	7%	13.6°
2041-05-03 Fri	—	unknown	—	72.5° 14:25	6.23	13%	26.4°
2041-05-04 Sat	—	unknown	—	72.5° 14:20	6.17	21%	38.9°
2041-05-05 Sun	—	unknown	—	72.5° 14:15	6.11	29%	51.2°
2041-05-06 Mon	—	unknown	—	72.5° 14:10	6.05	38%	63.2°
2041-05-07 Tue	—	unknown	—	72.5° 14:05	6.0	48%	75.1°
2041-05-08 Wed	—	unknown	—	72.5° 14:05	5.94	57%	86.9°
2041-05-09 Thu	—	unknown	—	72.5° 14:00	5.89	66%	98.8°
2041-05-10 Fri	—	unknown	—	72.5° 13:55	5.83	75%	110.7°
2041-05-11 Sat	—	unknown	—	72.5° 13:50	5.77	83%	122.8°
2041-05-12 Sun	—	unknown	—	72.5° 13:50	5.72	90%	135.2°
2041-05-13 Mon	—	unknown	—	72.5° 13:45	5.67	95%	147.8°
2041-05-14 Tue	—	unknown	—	72.5° 13:40	5.61	99%	160.6°
2041-05-15 Wed	—	unknown	—	72.5° 13:35	5.56	100%	173.5°
2041-05-16 Thu	—	unknown	—	72.5° 13:30	5.51	99%	171.9°
2041-05-17 Fri	—	unknown	—	72.5° 13:30	5.45	96%	158.5°
2041-05-18 Sat	—	unknown	—	72.5° 13:25	5.4	90%	144.6°
2041-05-19 Sun	—	unknown	—	72.5° 13:20	5.35	82%	130.5°
2041-05-20 Mon	—	unknown	—	72.5° 13:15	5.3	72%	116.4°
2041-05-21 Tue	—	unknown	—	72.5° 13:10	5.25	62%	102.2°
2041-05-22 Wed	—	unknown	—	72.5° 13:10	5.2	50%	88.1°
2041-05-23 Thu	—	unknown	—	72.5° 13:05	5.16	39%	73.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-24&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.