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.

2030-05-12astronomy score per night — click a bar for that night2030-06-10

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-05-12 Sun	—	unknown	—	72.5° 13:50	5.74	73%	110.2°
2030-05-13 Mon	—	unknown	—	72.5° 13:45	5.68	82%	124.2°
2030-05-14 Tue	—	unknown	—	72.5° 13:40	5.63	90%	138.7°
2030-05-15 Wed	—	unknown	—	72.5° 13:35	5.58	96%	153.5°
2030-05-16 Thu	—	unknown	—	72.5° 13:35	5.52	100%	168.5°
2030-05-17 Fri	—	unknown	—	72.5° 13:30	5.47	100%	175.2°
2030-05-18 Sat	—	unknown	—	72.5° 13:25	5.42	97%	160.6°
2030-05-19 Sun	—	unknown	—	72.5° 13:20	5.37	91%	145.7°
2030-05-20 Mon	—	unknown	—	72.5° 13:15	5.32	83%	131.1°
2030-05-21 Tue	—	unknown	—	72.5° 13:15	5.27	74%	116.9°
2030-05-22 Wed	—	unknown	—	72.5° 13:10	5.22	64%	103.2°
2030-05-23 Thu	—	unknown	—	72.5° 13:05	5.17	53%	89.9°
2030-05-24 Fri	—	unknown	—	72.5° 13:00	5.13	43%	77.1°
2030-05-25 Sat	—	unknown	—	72.5° 12:55	5.08	33%	64.5°
2030-05-26 Sun	—	unknown	—	72.5° 12:55	5.04	24%	52.3°
2030-05-27 Mon	—	unknown	—	72.5° 12:50	4.99	16%	40.2°
2030-05-28 Tue	—	unknown	—	72.5° 12:45	4.95	10%	28.3°
2030-05-29 Wed	—	unknown	—	72.5° 12:40	4.91	5%	16.5°
2030-05-30 Thu	—	unknown	—	72.5° 12:35	4.87	2%	5.2°
2030-05-31 Fri	—	unknown	—	72.5° 12:35	4.83	0%	7.8°
2030-06-01 Sat	—	unknown	—	72.5° 12:30	4.79	0%	19.4°
2030-06-02 Sun	—	unknown	—	72.5° 12:25	4.76	2%	31.2°
2030-06-03 Mon	—	unknown	—	72.5° 12:20	4.73	6%	43.2°
2030-06-04 Tue	—	unknown	—	72.5° 12:20	4.69	12%	55.3°
2030-06-05 Wed	—	unknown	—	72.5° 12:15	4.66	19%	67.6°
2030-06-06 Thu	—	unknown	—	72.5° 12:10	4.63	28%	80.1°
2030-06-07 Fri	—	unknown	—	72.5° 12:05	4.61	37%	92.9°
2030-06-08 Sat	—	unknown	—	72.5° 12:00	4.58	48%	106.0°
2030-06-09 Sun	—	unknown	—	72.5° 11:55	4.56	58%	119.4°
2030-06-10 Mon	—	unknown	—	72.5° 11:50	4.53	69%	133.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-05-12&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.