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.

2037-04-24astronomy score per night — click a bar for that night2037-05-23

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-04-24 Fri	—	unknown	—	79.2° 12:45	6.75	70%	113.1°
2037-04-25 Sat	—	unknown	—	79.1° 12:40	6.69	80%	125.8°
2037-04-26 Sun	—	unknown	—	79.2° 12:40	6.64	89%	138.0°
2037-04-27 Mon	—	unknown	—	79.2° 12:35	6.58	95%	148.5°
2037-04-28 Tue	—	unknown	—	79.2° 12:30	6.52	99%	155.0°
2037-04-29 Wed	—	unknown	—	79.2° 12:25	6.46	100%	154.3°
2037-04-30 Thu	—	unknown	—	79.1° 12:20	6.4	98%	147.1°
2037-05-01 Fri	—	unknown	—	79.2° 12:20	6.34	94%	136.9°
2037-05-02 Sat	—	unknown	—	79.2° 12:15	6.29	88%	125.7°
2037-05-03 Sun	—	unknown	—	79.2° 12:10	6.23	80%	114.2°
2037-05-04 Mon	—	unknown	—	79.2° 12:05	6.17	72%	102.8°
2037-05-05 Tue	—	unknown	—	79.2° 12:00	6.11	62%	91.5°
2037-05-06 Wed	—	unknown	—	79.2° 11:55	6.06	53%	80.5°
2037-05-07 Thu	—	unknown	—	79.2° 11:50	6.0	43%	69.7°
2037-05-08 Fri	—	unknown	—	79.2° 11:45	5.94	34%	59.2°
2037-05-09 Sat	—	unknown	—	79.2° 11:45	5.89	25%	49.0°
2037-05-10 Sun	—	unknown	—	79.2° 11:40	5.83	18%	39.5°
2037-05-11 Mon	—	unknown	—	79.2° 11:35	5.78	11%	31.2°
2037-05-12 Tue	—	unknown	—	79.2° 11:30	5.72	6%	25.5°
2037-05-13 Wed	—	unknown	—	79.1° 11:25	5.67	2%	24.8°
2037-05-14 Thu	—	unknown	—	79.2° 11:25	5.61	0%	29.6°
2037-05-15 Fri	—	unknown	—	79.2° 11:20	5.56	1%	38.1°
2037-05-16 Sat	—	unknown	—	79.2° 11:15	5.51	3%	48.5°
2037-05-17 Sun	—	unknown	—	79.2° 11:10	5.46	8%	60.0°
2037-05-18 Mon	—	unknown	—	79.1° 11:10	5.4	15%	72.1°
2037-05-19 Tue	—	unknown	—	79.2° 11:05	5.35	24%	84.6°
2037-05-20 Wed	—	unknown	—	79.2° 11:00	5.3	34%	97.2°
2037-05-21 Thu	—	unknown	—	79.2° 10:55	5.25	45%	109.9°
2037-05-22 Fri	—	unknown	—	79.2° 10:50	5.21	56%	122.5°
2037-05-23 Sat	—	unknown	—	79.2° 10:50	5.16	68%	134.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-04-24&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.