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.

2045-04-15astronomy score per night — click a bar for that night2045-05-14

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-04-15 Sat	—	unknown	—	72.6° 15:35	7.27	2%	49.9°
2045-04-16 Sun	—	unknown	—	72.6° 15:30	7.21	0%	37.0°
2045-04-17 Mon	—	unknown	—	72.6° 15:25	7.15	1%	23.8°
2045-04-18 Tue	—	unknown	—	72.6° 15:20	7.1	3%	10.3°
2045-04-19 Wed	—	unknown	—	72.6° 15:20	7.04	8%	3.5°
2045-04-20 Thu	—	unknown	—	72.6° 15:15	6.98	15%	17.3°
2045-04-21 Fri	—	unknown	—	72.6° 15:10	6.92	24%	31.2°
2045-04-22 Sat	—	unknown	—	72.6° 15:05	6.86	35%	45.3°
2045-04-23 Sun	—	unknown	—	72.6° 15:00	6.81	46%	59.4°
2045-04-24 Mon	—	unknown	—	72.6° 15:00	6.75	57%	73.6°
2045-04-25 Tue	—	unknown	—	72.6° 14:55	6.69	68%	87.8°
2045-04-26 Wed	—	unknown	—	72.6° 14:50	6.63	78%	101.9°
2045-04-27 Thu	—	unknown	—	72.6° 14:45	6.57	87%	116.0°
2045-04-28 Fri	—	unknown	—	72.6° 14:45	6.51	94%	130.0°
2045-04-29 Sat	—	unknown	—	72.6° 14:40	6.46	98%	143.8°
2045-04-30 Sun	—	unknown	—	72.6° 14:35	6.4	100%	157.3°
2045-05-01 Mon	—	unknown	—	72.6° 14:30	6.34	99%	170.6°
2045-05-02 Tue	—	unknown	—	72.6° 14:25	6.28	97%	176.2°
2045-05-03 Wed	—	unknown	—	72.6° 14:25	6.22	92%	163.5°
2045-05-04 Thu	—	unknown	—	72.6° 14:20	6.17	86%	151.1°
2045-05-05 Fri	—	unknown	—	72.6° 14:15	6.11	78%	138.9°
2045-05-06 Sat	—	unknown	—	72.6° 14:10	6.05	70%	126.9°
2045-05-07 Sun	—	unknown	—	72.6° 14:05	6.0	61%	115.0°
2045-05-08 Mon	—	unknown	—	72.6° 14:05	5.94	52%	103.1°
2045-05-09 Tue	—	unknown	—	72.6° 14:00	5.88	42%	91.2°
2045-05-10 Wed	—	unknown	—	72.6° 13:55	5.83	33%	79.2°
2045-05-11 Thu	—	unknown	—	72.6° 13:50	5.77	24%	67.0°
2045-05-12 Fri	—	unknown	—	72.6° 13:50	5.72	16%	54.6°
2045-05-13 Sat	—	unknown	—	72.6° 13:45	5.66	10%	41.8°
2045-05-14 Sun	—	unknown	—	72.6° 13:40	5.61	4%	28.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-04-15&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.