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.

Best nights for Seven Sisters: 07-07 (1), 07-08 (1), 07-09 (1), 07-10 (1) — by astronomy; check the weather when the night is within four days.

2040-06-11astronomy score per night — click a bar for that night2040-07-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-06-11 Mon	0	—	unknown	—	72.5° 11:45	4.5	4%	45.6°
2040-06-12 Tue	0	—	unknown	—	72.5° 11:40	4.49	9%	57.3°
2040-06-13 Wed	0	—	unknown	—	72.5° 11:35	4.47	15%	69.1°
2040-06-14 Thu	0	—	unknown	—	72.5° 11:35	4.46	22%	80.9°
2040-06-15 Fri	0	—	unknown	—	72.5° 11:30	4.45	31%	92.9°
2040-06-16 Sat	0	—	unknown	—	72.5° 11:25	4.44	40%	105.0°
2040-06-17 Sun	0	—	unknown	—	72.5° 11:20	4.43	50%	117.4°
2040-06-18 Mon	0	—	unknown	—	72.5° 11:15	4.43	61%	130.1°
2040-06-19 Tue	0	—	unknown	—	72.5° 11:15	4.42	71%	143.2°
2040-06-20 Wed	0	—	unknown	—	72.5° 11:10	4.42	80%	156.6°
2040-06-21 Thu	0	—	unknown	—	72.5° 11:05	4.42	88%	170.1°
2040-06-22 Fri	0	—	unknown	—	72.5° 11:00	4.43	95%	172.8°
2040-06-23 Sat	0	—	unknown	—	72.5° 10:55	4.43	99%	158.9°
2040-06-24 Sun	0	—	unknown	—	72.5° 10:55	4.44	100%	144.0°
2040-06-25 Mon	0	—	unknown	—	72.5° 10:50	4.45	98%	128.9°
2040-06-26 Tue	0	—	unknown	—	72.5° 10:45	4.46	93%	113.8°
2040-06-27 Wed	0	—	unknown	—	72.5° 10:40	4.48	86%	99.0°
2040-06-28 Thu	0	—	unknown	—	72.5° 10:40	4.49	76%	84.5°
2040-06-29 Fri	0	—	unknown	—	72.5° 10:35	4.51	66%	70.4°
2040-06-30 Sat	0	—	unknown	—	72.5° 10:30	4.53	55%	56.8°
2040-07-01 Sun	0	—	unknown	—	72.5° 10:25	4.55	45%	43.6°
2040-07-02 Mon	0	—	unknown	—	72.5° 10:20	4.57	34%	30.8°
2040-07-03 Tue	0	—	unknown	—	72.5° 10:20	4.6	25%	18.4°
2040-07-04 Wed	0	—	unknown	—	72.5° 10:15	4.63	17%	7.1°
2040-07-05 Thu	0	—	unknown	—	72.5° 10:10	4.66	10%	8.0°
2040-07-06 Fri	0	—	unknown	—	72.5° 10:05	4.69	5%	19.2°
2040-07-07 Sat	1	—	unknown	—	72.5° 10:00	4.72	2%	30.9°
2040-07-08 Sun	1	—	unknown	—	72.5° 10:00	4.75	0%	42.6°
2040-07-09 Mon	1	—	unknown	—	72.5° 09:55	4.79	0%	54.4°
2040-07-10 Tue	1	—	unknown	—	72.5° 09:50	4.82	2%	66.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-06-11&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.