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.

2041-05-19astronomy score per night — click a bar for that night2041-06-17

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2041-05-24 Fri	—	unknown	—	72.5° 13:00	5.11	28%	59.8°
2041-05-25 Sat	—	unknown	—	72.5° 12:55	5.07	18%	45.8°
2041-05-26 Sun	—	unknown	—	72.5° 12:55	5.02	10%	32.0°
2041-05-27 Mon	—	unknown	—	72.5° 12:50	4.98	5%	18.4°
2041-05-28 Tue	—	unknown	—	72.5° 12:45	4.94	1%	5.4°
2041-05-29 Wed	—	unknown	—	72.5° 12:40	4.9	0%	9.0°
2041-05-30 Thu	—	unknown	—	72.5° 12:35	4.86	1%	21.8°
2041-05-31 Fri	—	unknown	—	72.5° 12:35	4.82	4%	34.5°
2041-06-01 Sat	—	unknown	—	72.5° 12:30	4.78	9%	46.9°
2041-06-02 Sun	—	unknown	—	72.5° 12:25	4.75	16%	59.1°
2041-06-03 Mon	—	unknown	—	72.5° 12:20	4.71	23%	71.1°
2041-06-04 Tue	—	unknown	—	72.5° 12:15	4.68	32%	83.0°
2041-06-05 Wed	—	unknown	—	72.5° 12:15	4.65	41%	94.8°
2041-06-06 Thu	—	unknown	—	72.5° 12:10	4.62	50%	106.7°
2041-06-07 Fri	—	unknown	—	72.5° 12:05	4.6	60%	118.6°
2041-06-08 Sat	—	unknown	—	72.5° 12:00	4.57	69%	130.8°
2041-06-09 Sun	—	unknown	—	72.5° 11:55	4.55	78%	143.1°
2041-06-10 Mon	—	unknown	—	72.5° 11:50	4.53	86%	155.8°
2041-06-11 Tue	—	unknown	—	72.5° 11:45	4.51	92%	168.7°
2041-06-12 Wed	—	unknown	—	72.5° 11:40	4.49	97%	176.2°
2041-06-13 Thu	—	unknown	—	72.5° 11:40	4.47	100%	163.4°
2041-06-14 Fri	—	unknown	—	72.5° 11:35	4.46	100%	149.3°
2041-06-15 Sat	—	unknown	—	72.5° 11:30	4.45	97%	135.0°
2041-06-16 Sun	—	unknown	—	72.5° 11:25	4.44	92%	120.5°
2041-06-17 Mon	—	unknown	—	72.5° 11:20	4.43	84%	105.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-05-19&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.