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.

2031-05-19astronomy score per night — click a bar for that night2031-06-17

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-05-19 Mon	—	unknown	—	72.5° 13:20	5.38	2%	16.8°
2031-05-20 Tue	—	unknown	—	72.5° 13:20	5.33	0%	5.7°
2031-05-21 Wed	—	unknown	—	72.5° 13:15	5.28	0%	9.3°
2031-05-22 Thu	—	unknown	—	72.5° 13:10	5.23	2%	20.8°
2031-05-23 Fri	—	unknown	—	72.5° 13:05	5.18	6%	32.5°
2031-05-24 Sat	—	unknown	—	72.5° 13:00	5.14	12%	44.3°
2031-05-25 Sun	—	unknown	—	72.5° 13:00	5.09	18%	56.1°
2031-05-26 Mon	—	unknown	—	72.5° 12:55	5.05	26%	67.9°
2031-05-27 Tue	—	unknown	—	72.5° 12:50	5.0	35%	79.8°
2031-05-28 Wed	—	unknown	—	72.5° 12:45	4.96	45%	91.8°
2031-05-29 Thu	—	unknown	—	72.5° 12:40	4.92	55%	104.2°
2031-05-30 Fri	—	unknown	—	72.5° 12:40	4.88	65%	116.8°
2031-05-31 Sat	—	unknown	—	72.5° 12:35	4.84	74%	129.8°
2031-06-01 Sun	—	unknown	—	72.5° 12:30	4.8	83%	143.3°
2031-06-02 Mon	—	unknown	—	72.5° 12:25	4.77	91%	157.2°
2031-06-03 Tue	—	unknown	—	72.5° 12:25	4.73	96%	170.9°
2031-06-04 Wed	—	unknown	—	72.5° 12:20	4.7	100%	172.0°
2031-06-05 Thu	—	unknown	—	72.5° 12:15	4.67	100%	157.8°
2031-06-06 Fri	—	unknown	—	72.5° 12:10	4.64	97%	142.8°
2031-06-07 Sat	—	unknown	—	72.5° 12:05	4.61	91%	127.9°
2031-06-08 Sun	—	unknown	—	72.5° 12:00	4.59	83%	113.1°
2031-06-09 Mon	—	unknown	—	72.5° 11:55	4.56	74%	98.6°
2031-06-10 Tue	—	unknown	—	72.5° 11:50	4.54	63%	84.5°
2031-06-11 Wed	—	unknown	—	72.5° 11:45	4.52	52%	70.8°
2031-06-12 Thu	—	unknown	—	72.5° 11:45	4.5	41%	57.5°
2031-06-13 Fri	—	unknown	—	72.5° 11:40	4.48	31%	44.6°
2031-06-14 Sat	—	unknown	—	72.5° 11:35	4.47	22%	31.9°
2031-06-15 Sun	—	unknown	—	72.5° 11:30	4.46	14%	19.6°
2031-06-16 Mon	—	unknown	—	72.5° 11:30	4.44	8%	8.1°
2031-06-17 Tue	—	unknown	—	72.5° 11:25	4.44	4%	6.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-05-19&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.