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.

2043-05-20astronomy score per night — click a bar for that night2043-06-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-05-20 Wed	—	unknown	—	72.5° 13:20	5.33	92%	146.8°
2043-05-21 Thu	—	unknown	—	72.6° 13:15	5.28	96%	158.6°
2043-05-22 Fri	—	unknown	—	72.6° 13:10	5.23	99%	170.5°
2043-05-23 Sat	—	unknown	—	72.6° 13:05	5.18	100%	177.7°
2043-05-24 Sun	—	unknown	—	72.5° 13:00	5.13	99%	165.8°
2043-05-25 Mon	—	unknown	—	72.5° 13:00	5.09	96%	153.8°
2043-05-26 Tue	—	unknown	—	72.6° 12:55	5.04	92%	141.7°
2043-05-27 Wed	—	unknown	—	72.6° 12:50	5.0	86%	129.4°
2043-05-28 Thu	—	unknown	—	72.5° 12:45	4.96	78%	117.0°
2043-05-29 Fri	—	unknown	—	72.5° 12:45	4.92	69%	104.3°
2043-05-30 Sat	—	unknown	—	72.6° 12:40	4.88	59%	91.4°
2043-05-31 Sun	—	unknown	—	72.6° 12:35	4.84	49%	78.1°
2043-06-01 Mon	—	unknown	—	72.6° 12:30	4.8	38%	64.4°
2043-06-02 Tue	—	unknown	—	72.5° 12:25	4.76	27%	50.4°
2043-06-03 Wed	—	unknown	—	72.5° 12:25	4.73	17%	35.9°
2043-06-04 Thu	—	unknown	—	72.6° 12:20	4.7	9%	21.1°
2043-06-05 Fri	—	unknown	—	72.6° 12:15	4.67	4%	6.0°
2043-06-06 Sat	—	unknown	—	72.6° 12:10	4.64	1%	9.1°
2043-06-07 Sun	—	unknown	—	72.5° 12:05	4.61	0%	24.2°
2043-06-08 Mon	—	unknown	—	72.6° 12:00	4.58	4%	39.0°
2043-06-09 Tue	—	unknown	—	72.6° 12:00	4.56	9%	53.5°
2043-06-10 Wed	—	unknown	—	72.5° 11:50	4.54	16%	67.6°
2043-06-11 Thu	—	unknown	—	72.5° 11:50	4.52	25%	81.2°
2043-06-12 Fri	—	unknown	—	72.6° 11:45	4.5	35%	94.4°
2043-06-13 Sat	—	unknown	—	72.6° 11:40	4.48	45%	107.1°
2043-06-14 Sun	—	unknown	—	72.6° 11:35	4.47	55%	119.6°
2043-06-15 Mon	—	unknown	—	72.5° 11:30	4.45	64%	131.7°
2043-06-16 Tue	—	unknown	—	72.5° 11:30	4.44	73%	143.7°
2043-06-17 Wed	—	unknown	—	72.6° 11:25	4.43	81%	155.6°
2043-06-18 Thu	—	unknown	—	72.6° 11:20	4.43	88%	167.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-05-20&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.