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.

2038-05-21astronomy score per night — click a bar for that night2038-06-19

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-05-21 Fri	—	unknown	—	42.9° 15:00	5.27	87%	145.0°
2038-05-22 Sat	—	unknown	—	42.9° 14:55	5.22	78%	135.5°
2038-05-23 Sun	—	unknown	—	42.9° 14:55	5.17	69%	124.9°
2038-05-24 Mon	—	unknown	—	42.9° 14:50	5.12	59%	114.0°
2038-05-25 Tue	—	unknown	—	42.9° 14:45	5.08	49%	103.1°
2038-05-26 Wed	—	unknown	—	42.9° 14:40	5.03	40%	92.3°
2038-05-27 Thu	—	unknown	—	42.9° 14:40	4.99	31%	81.7°
2038-05-28 Fri	—	unknown	—	42.9° 14:35	4.95	22%	71.2°
2038-05-29 Sat	—	unknown	—	42.9° 14:30	4.91	15%	61.0°
2038-05-30 Sun	—	unknown	—	42.9° 14:25	4.87	9%	51.1°
2038-05-31 Mon	—	unknown	—	42.9° 14:20	4.83	4%	41.8°
2038-06-01 Tue	—	unknown	—	42.9° 14:20	4.79	1%	33.8°
2038-06-02 Wed	—	unknown	—	42.9° 14:15	4.76	0%	28.4°
2038-06-03 Thu	—	unknown	—	42.9° 14:10	4.72	1%	27.2°
2038-06-04 Fri	—	unknown	—	42.9° 14:05	4.69	4%	31.0°
2038-06-05 Sat	—	unknown	—	42.9° 14:00	4.66	8%	38.6°
2038-06-06 Sun	—	unknown	—	42.9° 14:00	4.63	15%	48.3°
2038-06-07 Mon	—	unknown	—	42.9° 13:55	4.6	23%	59.1°
2038-06-08 Tue	—	unknown	—	42.9° 13:50	4.58	33%	70.8°
2038-06-09 Wed	—	unknown	—	42.9° 13:45	4.55	44%	82.9°
2038-06-10 Thu	—	unknown	—	42.9° 13:45	4.53	55%	95.3°
2038-06-11 Fri	—	unknown	—	42.9° 13:40	4.51	66%	107.9°
2038-06-12 Sat	—	unknown	—	42.9° 13:35	4.49	77%	120.4°
2038-06-13 Sun	—	unknown	—	42.9° 13:30	4.48	86%	132.4°
2038-06-14 Mon	—	unknown	—	42.9° 13:25	4.46	93%	143.1°
2038-06-15 Tue	—	unknown	—	42.9° 13:25	4.45	98%	150.9°
2038-06-16 Wed	—	unknown	—	42.9° 13:20	4.44	100%	152.8°
2038-06-17 Thu	—	unknown	—	42.9° 13:15	4.43	99%	148.2°
2038-06-18 Fri	—	unknown	—	42.9° 13:10	4.43	96%	139.5°
2038-06-19 Sat	—	unknown	—	42.9° 13:05	4.42	90%	129.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-05-21&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.