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.

2031-07-13astronomy score per night — click a bar for that night2031-08-11

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-07-13 Sun	—	unknown	—	42.9° 11:30	4.91	26%	43.3°
2031-07-14 Mon	—	unknown	—	42.9° 11:25	4.95	18%	34.8°
2031-07-15 Tue	—	unknown	—	42.9° 11:20	4.99	12%	28.6°
2031-07-16 Wed	—	unknown	—	42.9° 11:20	5.03	6%	26.3°
2031-07-17 Thu	—	unknown	—	42.9° 11:15	5.08	2%	28.8°
2031-07-18 Fri	—	unknown	—	42.9° 11:10	5.12	0%	35.0°
2031-07-19 Sat	—	unknown	—	42.9° 11:05	5.17	0%	43.4°
2031-07-20 Sun	—	unknown	—	42.9° 11:00	5.21	2%	52.9°
2031-07-21 Mon	—	unknown	—	42.9° 11:00	5.26	5%	63.1°
2031-07-22 Tue	—	unknown	—	42.9° 10:55	5.31	10%	73.7°
2031-07-23 Wed	—	unknown	—	42.9° 10:50	5.36	17%	84.7°
2031-07-24 Thu	—	unknown	—	42.9° 10:45	5.41	25%	95.8°
2031-07-25 Fri	—	unknown	—	42.9° 10:45	5.46	34%	107.1°
2031-07-26 Sat	—	unknown	—	42.9° 10:40	5.51	45%	118.5°
2031-07-27 Sun	—	unknown	—	42.9° 10:35	5.57	55%	129.8°
2031-07-28 Mon	—	unknown	—	42.9° 10:30	5.62	66%	140.5°
2031-07-29 Tue	—	unknown	—	42.9° 10:25	5.67	77%	149.3°
2031-07-30 Wed	—	unknown	—	42.9° 10:25	5.73	86%	153.7°
2031-07-31 Thu	—	unknown	—	42.9° 10:20	5.78	93%	150.9°
2031-08-01 Fri	—	unknown	—	42.9° 10:15	5.84	98%	142.3°
2031-08-02 Sat	—	unknown	—	42.9° 10:10	5.89	100%	130.8°
2031-08-03 Sun	—	unknown	—	42.9° 10:05	5.95	99%	118.1°
2031-08-04 Mon	—	unknown	—	42.9° 10:05	6.0	95%	105.1°
2031-08-05 Tue	—	unknown	—	42.9° 10:00	6.06	88%	92.1°
2031-08-06 Wed	—	unknown	—	42.9° 09:55	6.12	80%	79.6°
2031-08-07 Thu	—	unknown	—	42.9° 09:50	6.17	71%	67.6°
2031-08-08 Fri	—	unknown	—	42.9° 09:50	6.23	61%	56.3°
2031-08-09 Sat	—	unknown	—	42.9° 09:45	6.29	51%	45.8°
2031-08-10 Sun	—	unknown	—	42.9° 09:40	6.34	41%	36.7°
2031-08-11 Mon	—	unknown	—	42.9° 09:35	6.4	32%	29.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-07-13&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.