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.

2042-08-20astronomy score per night — click a bar for that night2042-09-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-08-20 Wed	—	unknown	—	50.1° 15:55	6.94	23%	20.3°
2042-08-21 Thu	—	unknown	—	50.1° 15:50	6.99	32%	32.0°
2042-08-22 Fri	—	unknown	—	50.1° 15:50	7.05	41%	43.8°
2042-08-23 Sat	—	unknown	—	50.1° 15:45	7.11	50%	55.8°
2042-08-24 Sun	—	unknown	—	50.1° 15:40	7.17	60%	68.1°
2042-08-25 Mon	—	unknown	—	50.1° 15:35	7.22	70%	80.7°
2042-08-26 Tue	—	unknown	—	50.1° 15:35	7.28	79%	93.7°
2042-08-27 Wed	—	unknown	—	50.1° 15:30	7.34	87%	107.1°
2042-08-28 Thu	—	unknown	—	50.1° 15:25	7.39	94%	120.9°
2042-08-29 Fri	—	unknown	—	50.1° 15:20	7.45	98%	135.2°
2042-08-30 Sat	—	unknown	—	50.1° 15:15	7.51	100%	149.7°
2042-08-31 Sun	—	unknown	—	50.1° 15:15	7.56	99%	164.4°
2042-09-01 Mon	—	unknown	—	50.1° 15:10	7.62	95%	176.4°
2042-09-02 Tue	—	unknown	—	50.1° 15:05	7.67	88%	164.9°
2042-09-03 Wed	—	unknown	—	50.1° 15:00	7.73	80%	150.4°
2042-09-04 Thu	—	unknown	—	50.1° 14:55	7.78	70%	136.0°
2042-09-05 Fri	—	unknown	—	50.1° 14:55	7.84	59%	121.9°
2042-09-06 Sat	—	unknown	—	50.1° 14:50	7.89	48%	108.2°
2042-09-07 Sun	—	unknown	—	50.1° 14:45	7.95	37%	94.7°
2042-09-08 Mon	—	unknown	—	50.1° 14:40	8.0	27%	81.6°
2042-09-09 Tue	—	unknown	—	50.1° 14:40	8.06	18%	68.8°
2042-09-10 Wed	—	unknown	—	50.1° 14:35	8.11	11%	56.1°
2042-09-11 Thu	—	unknown	—	50.1° 14:30	8.17	6%	43.7°
2042-09-12 Fri	—	unknown	—	50.1° 14:25	8.22	2%	31.5°
2042-09-13 Sat	—	unknown	—	50.1° 14:20	8.27	0%	19.5°
2042-09-14 Sun	—	unknown	—	50.1° 14:20	8.33	0%	8.1°
2042-09-15 Mon	—	unknown	—	50.1° 14:15	8.38	2%	6.0°
2042-09-16 Tue	—	unknown	—	50.1° 14:10	8.43	6%	16.9°
2042-09-17 Wed	—	unknown	—	50.1° 14:05	8.48	11%	28.6°
2042-09-18 Thu	—	unknown	—	50.1° 14:00	8.54	18%	40.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-08-20&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.