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.

2034-05-18astronomy score per night — click a bar for that night2034-06-16

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2034-05-18 Thu	—	unknown	—	42.9° 15:15	5.42	1%	27.2°
2034-05-19 Fri	—	unknown	—	42.9° 15:10	5.37	5%	23.7°
2034-05-20 Sat	—	unknown	—	42.9° 15:05	5.32	11%	28.1°
2034-05-21 Sun	—	unknown	—	42.9° 15:00	5.27	20%	37.3°
2034-05-22 Mon	—	unknown	—	42.9° 14:55	5.22	29%	48.4°
2034-05-23 Tue	—	unknown	—	42.9° 14:55	5.17	39%	59.8°
2034-05-24 Wed	—	unknown	—	42.9° 14:50	5.13	49%	71.4°
2034-05-25 Thu	—	unknown	—	42.9° 14:45	5.08	59%	82.7°
2034-05-26 Fri	—	unknown	—	42.9° 14:40	5.04	69%	93.9°
2034-05-27 Sat	—	unknown	—	42.9° 14:40	4.99	77%	104.9°
2034-05-28 Sun	—	unknown	—	42.9° 14:35	4.95	85%	115.6°
2034-05-29 Mon	—	unknown	—	42.9° 14:30	4.91	91%	126.1°
2034-05-30 Tue	—	unknown	—	42.9° 14:25	4.87	95%	136.1°
2034-05-31 Wed	—	unknown	—	42.9° 14:20	4.83	98%	145.2°
2034-06-01 Thu	—	unknown	—	42.9° 14:20	4.79	100%	152.5°
2034-06-02 Fri	—	unknown	—	42.9° 14:15	4.76	99%	156.2°
2034-06-03 Sat	—	unknown	—	42.9° 14:10	4.72	97%	154.4°
2034-06-04 Sun	—	unknown	—	42.9° 14:05	4.69	93%	148.0°
2034-06-05 Mon	—	unknown	—	42.9° 14:00	4.66	87%	138.8°
2034-06-06 Tue	—	unknown	—	42.9° 14:00	4.63	79%	128.2°
2034-06-07 Wed	—	unknown	—	42.9° 13:55	4.61	70%	116.9°
2034-06-08 Thu	—	unknown	—	42.9° 13:50	4.58	60%	104.9°
2034-06-09 Fri	—	unknown	—	42.9° 13:45	4.56	49%	92.6°
2034-06-10 Sat	—	unknown	—	42.9° 13:45	4.53	38%	79.8°
2034-06-11 Sun	—	unknown	—	42.9° 13:40	4.51	27%	66.9°
2034-06-12 Mon	—	unknown	—	42.9° 13:35	4.5	17%	54.0°
2034-06-13 Tue	—	unknown	—	42.9° 13:30	4.48	9%	41.6°
2034-06-14 Wed	—	unknown	—	42.9° 13:25	4.47	4%	30.8°
2034-06-15 Thu	—	unknown	—	42.9° 13:25	4.45	1%	24.3°
2034-06-16 Fri	—	unknown	—	42.9° 13:20	4.44	0%	25.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2034-05-18&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.