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.

2042-05-18astronomy score per night — click a bar for that night2042-06-16

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-05-18 Sun	—	unknown	—	72.5° 13:25	5.41	0%	9.0°
2042-05-19 Mon	—	unknown	—	72.5° 13:20	5.36	0%	5.8°
2042-05-20 Tue	—	unknown	—	72.5° 13:15	5.31	3%	20.0°
2042-05-21 Wed	—	unknown	—	72.5° 13:15	5.26	8%	33.8°
2042-05-22 Thu	—	unknown	—	72.5° 13:10	5.22	15%	47.3°
2042-05-23 Fri	—	unknown	—	72.5° 13:05	5.17	23%	60.4°
2042-05-24 Sat	—	unknown	—	72.5° 13:00	5.12	32%	73.1°
2042-05-25 Sun	—	unknown	—	72.5° 12:55	5.08	42%	85.4°
2042-05-26 Mon	—	unknown	—	72.5° 12:55	5.03	52%	97.5°
2042-05-27 Tue	—	unknown	—	72.5° 12:50	4.99	61%	109.5°
2042-05-28 Wed	—	unknown	—	72.5° 12:45	4.95	70%	121.3°
2042-05-29 Thu	—	unknown	—	72.5° 12:40	4.91	78%	133.2°
2042-05-30 Fri	—	unknown	—	72.5° 12:40	4.87	86%	145.1°
2042-05-31 Sat	—	unknown	—	72.5° 12:35	4.83	92%	157.1°
2042-06-01 Sun	—	unknown	—	72.5° 12:30	4.79	96%	169.3°
2042-06-02 Mon	—	unknown	—	72.5° 12:25	4.76	99%	177.9°
2042-06-03 Tue	—	unknown	—	72.5° 12:20	4.72	100%	165.6°
2042-06-04 Wed	—	unknown	—	72.5° 12:20	4.69	99%	152.8°
2042-06-05 Thu	—	unknown	—	72.5° 12:15	4.66	95%	139.7°
2042-06-06 Fri	—	unknown	—	72.5° 12:10	4.63	90%	126.4°
2042-06-07 Sat	—	unknown	—	72.5° 12:05	4.6	82%	112.9°
2042-06-08 Sun	—	unknown	—	72.5° 12:00	4.58	73%	99.2°
2042-06-09 Mon	—	unknown	—	72.5° 11:55	4.55	62%	85.4°
2042-06-10 Tue	—	unknown	—	72.5° 11:50	4.53	51%	71.4°
2042-06-11 Wed	—	unknown	—	72.5° 11:45	4.51	40%	57.2°
2042-06-12 Thu	—	unknown	—	72.5° 11:45	4.49	29%	42.9°
2042-06-13 Fri	—	unknown	—	72.5° 11:40	4.48	19%	28.6°
2042-06-14 Sat	—	unknown	—	72.5° 11:35	4.46	11%	14.2°
2042-06-15 Sun	—	unknown	—	72.5° 11:30	4.45	5%	1.3°
2042-06-16 Mon	—	unknown	—	72.5° 11:25	4.44	1%	14.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-05-18&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.