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.

2045-04-27astronomy score per night — click a bar for that night2045-05-26

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-04-27 Thu	—	unknown	—	42.9° 16:35	6.57	87%	91.3°
2045-04-28 Fri	—	unknown	—	42.9° 16:30	6.51	94%	102.9°
2045-04-29 Sat	—	unknown	—	42.9° 16:25	6.46	98%	114.1°
2045-04-30 Sun	—	unknown	—	42.9° 16:25	6.4	100%	124.7°
2045-05-01 Mon	—	unknown	—	42.9° 16:20	6.34	99%	134.0°
2045-05-02 Tue	—	unknown	—	42.9° 16:15	6.28	97%	141.4°
2045-05-03 Wed	—	unknown	—	42.9° 16:10	6.22	92%	145.9°
2045-05-04 Thu	—	unknown	—	42.9° 16:05	6.17	86%	146.5°
2045-05-05 Fri	—	unknown	—	42.9° 16:05	6.11	78%	143.3°
2045-05-06 Sat	—	unknown	—	42.9° 16:00	6.05	70%	137.3°
2045-05-07 Sun	—	unknown	—	42.9° 15:55	6.0	61%	129.5°
2045-05-08 Mon	—	unknown	—	42.9° 15:50	5.94	52%	120.7°
2045-05-09 Tue	—	unknown	—	42.9° 15:50	5.88	42%	111.3°
2045-05-10 Wed	—	unknown	—	42.9° 15:45	5.83	33%	101.5°
2045-05-11 Thu	—	unknown	—	42.9° 15:40	5.77	24%	91.3°
2045-05-12 Fri	—	unknown	—	42.9° 15:35	5.72	16%	80.9°
2045-05-13 Sat	—	unknown	—	42.9° 15:30	5.66	10%	70.3°
2045-05-14 Sun	—	unknown	—	42.9° 15:30	5.61	4%	59.9°
2045-05-15 Mon	—	unknown	—	42.9° 15:25	5.56	1%	49.9°
2045-05-16 Tue	—	unknown	—	42.9° 15:20	5.5	0%	41.1°
2045-05-17 Wed	—	unknown	—	42.9° 15:15	5.45	2%	34.9°
2045-05-18 Thu	—	unknown	—	42.9° 15:10	5.4	6%	33.2°
2045-05-19 Fri	—	unknown	—	42.9° 15:10	5.35	13%	36.8°
2045-05-20 Sat	—	unknown	—	42.9° 15:05	5.3	22%	44.4°
2045-05-21 Sun	—	unknown	—	42.9° 15:00	5.25	32%	54.3°
2045-05-22 Mon	—	unknown	—	42.9° 14:55	5.2	43%	65.3°
2045-05-23 Tue	—	unknown	—	42.9° 14:55	5.16	55%	76.8°
2045-05-24 Wed	—	unknown	—	42.9° 14:50	5.11	66%	88.4°
2045-05-25 Thu	—	unknown	—	42.9° 14:45	5.06	76%	99.9°
2045-05-26 Fri	—	unknown	—	42.9° 14:40	5.02	84%	111.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-04-27&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.