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.

2042-05-20astronomy score per night — click a bar for that night2042-06-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-05-20 Tue	—	unknown	—	42.9° 15:05	5.31	3%	33.0°
2042-05-21 Wed	—	unknown	—	42.9° 15:00	5.26	8%	35.0°
2042-05-22 Thu	—	unknown	—	42.9° 14:55	5.22	15%	41.1°
2042-05-23 Fri	—	unknown	—	42.9° 14:55	5.17	23%	49.4°
2042-05-24 Sat	—	unknown	—	42.9° 14:50	5.12	32%	58.7°
2042-05-25 Sun	—	unknown	—	42.9° 14:45	5.08	42%	68.5°
2042-05-26 Mon	—	unknown	—	42.9° 14:40	5.03	52%	78.5°
2042-05-27 Tue	—	unknown	—	42.9° 14:40	4.99	61%	88.5°
2042-05-28 Wed	—	unknown	—	42.9° 14:35	4.95	70%	98.4°
2042-05-29 Thu	—	unknown	—	42.9° 14:30	4.91	78%	108.2°
2042-05-30 Fri	—	unknown	—	42.9° 14:25	4.87	86%	117.8°
2042-05-31 Sat	—	unknown	—	42.9° 14:20	4.83	92%	127.0°
2042-06-01 Sun	—	unknown	—	42.9° 14:20	4.79	96%	135.4°
2042-06-02 Mon	—	unknown	—	42.9° 14:15	4.76	99%	142.2°
2042-06-03 Tue	—	unknown	—	42.9° 14:10	4.72	100%	146.4°
2042-06-04 Wed	—	unknown	—	42.9° 14:05	4.69	99%	146.6°
2042-06-05 Thu	—	unknown	—	42.9° 14:00	4.66	95%	142.6°
2042-06-06 Fri	—	unknown	—	42.9° 14:00	4.63	90%	135.2°
2042-06-07 Sat	—	unknown	—	42.9° 13:55	4.6	82%	125.9°
2042-06-08 Sun	—	unknown	—	42.9° 13:50	4.58	73%	115.3°
2042-06-09 Mon	—	unknown	—	42.9° 13:45	4.55	62%	104.0°
2042-06-10 Tue	—	unknown	—	42.9° 13:45	4.53	51%	92.3°
2042-06-11 Wed	—	unknown	—	42.9° 13:40	4.51	40%	80.4°
2042-06-12 Thu	—	unknown	—	42.9° 13:35	4.49	29%	68.6°
2042-06-13 Fri	—	unknown	—	42.9° 13:30	4.48	19%	57.3°
2042-06-14 Sat	—	unknown	—	42.9° 13:25	4.46	11%	46.9°
2042-06-15 Sun	—	unknown	—	42.9° 13:25	4.45	5%	38.5°
2042-06-16 Mon	—	unknown	—	42.9° 13:20	4.44	1%	33.6°
2042-06-17 Tue	—	unknown	—	42.9° 13:15	4.43	0%	33.6°
2042-06-18 Wed	—	unknown	—	42.9° 13:10	4.43	2%	38.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-05-20&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.