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.

2043-09-18astronomy score per night — click a bar for that night2043-10-17

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-09-18 Fri	—	unknown	—	50.1° 14:05	8.52	100%	167.4°
2043-09-19 Sat	—	unknown	—	50.1° 14:00	8.57	99%	174.0°
2043-09-20 Sun	—	unknown	—	50.1° 13:55	8.63	95%	162.0°
2043-09-21 Mon	—	unknown	—	50.1° 13:50	8.68	89%	147.8°
2043-09-22 Tue	—	unknown	—	50.1° 13:50	8.73	81%	133.4°
2043-09-23 Wed	—	unknown	—	50.1° 13:45	8.78	71%	119.0°
2043-09-24 Thu	—	unknown	—	50.1° 13:40	8.83	60%	104.8°
2043-09-25 Fri	—	unknown	—	50.1° 13:35	8.88	48%	90.8°
2043-09-26 Sat	—	unknown	—	50.1° 13:30	8.93	37%	77.0°
2043-09-27 Sun	—	unknown	—	50.1° 13:30	8.98	27%	63.4°
2043-09-28 Mon	—	unknown	—	50.1° 13:25	9.03	18%	50.0°
2043-09-29 Tue	—	unknown	—	50.1° 13:20	9.08	10%	36.9°
2043-09-30 Wed	—	unknown	—	50.1° 13:15	9.13	5%	24.1°
2043-10-01 Thu	—	unknown	—	50.1° 13:10	9.17	2%	12.0°
2043-10-02 Fri	—	unknown	—	50.1° 13:10	9.22	0%	5.6°
2043-10-03 Sat	—	unknown	—	50.1° 13:05	9.27	1%	15.2°
2043-10-04 Sun	—	unknown	—	50.1° 13:00	9.32	3%	26.9°
2043-10-05 Mon	—	unknown	—	50.1° 12:55	9.36	7%	38.8°
2043-10-06 Tue	—	unknown	—	50.1° 12:55	9.41	13%	50.6°
2043-10-07 Wed	—	unknown	—	50.1° 12:50	9.46	20%	62.4°
2043-10-08 Thu	—	unknown	—	50.1° 12:45	9.5	28%	74.1°
2043-10-09 Fri	—	unknown	—	50.1° 12:40	9.55	37%	85.9°
2043-10-10 Sat	—	unknown	—	50.1° 12:35	9.59	46%	97.8°
2043-10-11 Sun	—	unknown	—	50.1° 12:35	9.64	56%	110.0°
2043-10-12 Mon	—	unknown	—	50.1° 12:30	9.68	66%	122.4°
2043-10-13 Tue	—	unknown	—	50.1° 12:25	9.73	75%	135.1°
2043-10-14 Wed	—	unknown	—	50.1° 12:20	9.77	84%	148.2°
2043-10-15 Thu	—	unknown	—	50.1° 12:15	9.82	91%	161.6°
2043-10-16 Fri	—	unknown	—	50.1° 12:15	9.86	96%	173.7°
2043-10-17 Sat	—	unknown	—	50.1° 12:10	9.9	100%	167.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-09-18&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.