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.

2035-05-13astronomy score per night — click a bar for that night2035-06-11

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-05-13 Sun	—	unknown	—	72.5° 13:45	5.7	44%	77.0°
2035-05-14 Mon	—	unknown	—	72.5° 13:40	5.64	55%	90.4°
2035-05-15 Tue	—	unknown	—	72.5° 13:40	5.59	66%	103.5°
2035-05-16 Wed	—	unknown	—	72.5° 13:35	5.53	75%	116.3°
2035-05-17 Thu	—	unknown	—	72.5° 13:30	5.48	83%	128.8°
2035-05-18 Fri	—	unknown	—	72.5° 13:25	5.43	90%	140.9°
2035-05-19 Sat	—	unknown	—	72.5° 13:20	5.38	95%	152.7°
2035-05-20 Sun	—	unknown	—	72.5° 13:20	5.33	98%	163.6°
2035-05-21 Mon	—	unknown	—	72.5° 13:15	5.28	100%	170.8°
2035-05-22 Tue	—	unknown	—	72.5° 13:10	5.23	99%	166.4°
2035-05-23 Wed	—	unknown	—	72.5° 13:05	5.18	97%	156.2°
2035-05-24 Thu	—	unknown	—	72.5° 13:00	5.14	93%	145.1°
2035-05-25 Fri	—	unknown	—	72.5° 13:00	5.09	88%	133.6°
2035-05-26 Sat	—	unknown	—	72.5° 12:55	5.05	81%	121.9°
2035-05-27 Sun	—	unknown	—	72.5° 12:50	5.0	73%	110.1°
2035-05-28 Mon	—	unknown	—	72.5° 12:45	4.96	64%	98.1°
2035-05-29 Tue	—	unknown	—	72.5° 12:45	4.92	54%	85.8°
2035-05-30 Wed	—	unknown	—	72.5° 12:40	4.88	44%	73.2°
2035-05-31 Thu	—	unknown	—	72.5° 12:35	4.84	33%	60.3°
2035-06-01 Fri	—	unknown	—	72.5° 12:30	4.8	24%	46.9°
2035-06-02 Sat	—	unknown	—	72.5° 12:25	4.77	15%	33.3°
2035-06-03 Sun	—	unknown	—	72.5° 12:25	4.73	7%	19.7°
2035-06-04 Mon	—	unknown	—	72.5° 12:20	4.7	2%	9.4°
2035-06-05 Tue	—	unknown	—	72.5° 12:15	4.67	0%	15.3°
2035-06-06 Wed	—	unknown	—	72.5° 12:10	4.64	1%	29.0°
2035-06-07 Thu	—	unknown	—	72.5° 12:05	4.61	5%	43.6°
2035-06-08 Fri	—	unknown	—	72.5° 12:00	4.59	12%	58.2°
2035-06-09 Sat	—	unknown	—	72.5° 11:55	4.56	20%	72.6°
2035-06-10 Sun	—	unknown	—	72.5° 11:50	4.54	30%	86.5°
2035-06-11 Mon	—	unknown	—	72.5° 11:45	4.52	40%	100.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-05-13&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.