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.

2031-05-04astronomy score per night — click a bar for that night2031-06-02

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-05-04 Sun	—	unknown	—	72.5° 14:20	6.2	94%	135.3°
2031-05-05 Mon	—	unknown	—	72.5° 14:15	6.14	98%	149.1°
2031-05-06 Tue	—	unknown	—	72.5° 14:15	6.09	100%	163.2°
2031-05-07 Wed	—	unknown	—	72.5° 14:10	6.03	99%	175.4°
2031-05-08 Thu	—	unknown	—	72.5° 14:05	5.97	96%	166.2°
2031-05-09 Fri	—	unknown	—	72.5° 14:00	5.92	89%	151.8°
2031-05-10 Sat	—	unknown	—	72.5° 13:55	5.86	81%	137.3°
2031-05-11 Sun	—	unknown	—	72.5° 13:55	5.81	71%	122.8°
2031-05-12 Mon	—	unknown	—	72.5° 13:50	5.75	60%	108.6°
2031-05-13 Tue	—	unknown	—	72.5° 13:45	5.7	48%	94.7°
2031-05-14 Wed	—	unknown	—	72.5° 13:40	5.64	38%	81.0°
2031-05-15 Thu	—	unknown	—	72.5° 13:35	5.59	27%	67.7°
2031-05-16 Fri	—	unknown	—	72.5° 13:35	5.54	18%	54.5°
2031-05-17 Sat	—	unknown	—	72.5° 13:30	5.48	11%	41.7°
2031-05-18 Sun	—	unknown	—	72.5° 13:25	5.43	6%	29.0°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-05-04&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.