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.

2039-05-11astronomy score per night — click a bar for that night2039-06-09

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-05-11 Wed	—	unknown	—	42.9° 15:40	5.8	83%	145.9°
2039-05-12 Thu	—	unknown	—	42.9° 15:40	5.75	74%	136.8°
2039-05-13 Fri	—	unknown	—	42.9° 15:35	5.69	63%	126.1°
2039-05-14 Sat	—	unknown	—	42.9° 15:30	5.64	52%	114.9°
2039-05-15 Sun	—	unknown	—	42.9° 15:25	5.59	42%	103.6°
2039-05-16 Mon	—	unknown	—	42.9° 15:20	5.53	32%	92.4°
2039-05-17 Tue	—	unknown	—	42.9° 15:20	5.48	23%	81.4°
2039-05-18 Wed	—	unknown	—	42.9° 15:15	5.43	15%	70.7°
2039-05-19 Thu	—	unknown	—	42.9° 15:10	5.38	9%	60.4°
2039-05-20 Fri	—	unknown	—	42.9° 15:05	5.33	4%	50.7°
2039-05-21 Sat	—	unknown	—	42.9° 15:00	5.28	1%	41.8°
2039-05-22 Sun	—	unknown	—	42.9° 15:00	5.23	0%	34.4°
2039-05-23 Mon	—	unknown	—	42.9° 14:55	5.18	1%	29.7°
2039-05-24 Tue	—	unknown	—	42.9° 14:50	5.13	3%	28.9°
2039-05-25 Wed	—	unknown	—	42.9° 14:45	5.09	7%	32.3°
2039-05-26 Thu	—	unknown	—	42.9° 14:45	5.04	13%	38.9°
2039-05-27 Fri	—	unknown	—	42.9° 14:40	5.0	20%	47.5°
2039-05-28 Sat	—	unknown	—	42.9° 14:35	4.96	28%	57.2°
2039-05-29 Sun	—	unknown	—	42.9° 14:30	4.92	38%	67.7°
2039-05-30 Mon	—	unknown	—	42.9° 14:25	4.88	48%	78.8°
2039-05-31 Tue	—	unknown	—	42.9° 14:25	4.84	59%	90.4°
2039-06-01 Wed	—	unknown	—	42.9° 14:20	4.8	69%	102.4°
2039-06-02 Thu	—	unknown	—	42.9° 14:15	4.77	79%	114.5°
2039-06-03 Fri	—	unknown	—	42.9° 14:10	4.73	88%	126.6°
2039-06-04 Sat	—	unknown	—	42.9° 14:05	4.7	95%	137.9°
2039-06-05 Sun	—	unknown	—	42.9° 14:05	4.67	99%	147.0°
2039-06-06 Mon	—	unknown	—	42.9° 14:00	4.64	100%	151.3°
2039-06-07 Tue	—	unknown	—	42.9° 13:55	4.61	98%	148.7°
2039-06-08 Wed	—	unknown	—	42.9° 13:50	4.58	93%	140.7°
2039-06-09 Thu	—	unknown	—	42.9° 13:50	4.56	86%	130.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-05-11&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.