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.

2042-09-09astronomy score per night — click a bar for that night2042-10-08

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2042-09-19 Fri	—	unknown	—	50.1° 14:00	8.59	25%	52.2°
2042-09-20 Sat	—	unknown	—	50.1° 13:55	8.64	34%	64.2°
2042-09-21 Sun	—	unknown	—	50.1° 13:50	8.69	44%	76.4°
2042-09-22 Mon	—	unknown	—	50.1° 13:45	8.74	54%	88.9°
2042-09-23 Tue	—	unknown	—	50.1° 13:45	8.79	64%	101.8°
2042-09-24 Wed	—	unknown	—	50.1° 13:40	8.84	74%	115.1°
2042-09-25 Thu	—	unknown	—	50.1° 13:35	8.89	83%	128.9°
2042-09-26 Fri	—	unknown	—	50.1° 13:30	8.94	91%	143.1°
2042-09-27 Sat	—	unknown	—	50.1° 13:25	8.99	96%	157.7°
2042-09-28 Sun	—	unknown	—	50.1° 13:25	9.04	100%	172.1°
2042-09-29 Mon	—	unknown	—	50.1° 13:20	9.09	100%	171.0°
2042-09-30 Tue	—	unknown	—	50.1° 13:15	9.14	97%	156.3°
2042-10-01 Wed	—	unknown	—	50.1° 13:10	9.19	91%	141.3°
2042-10-02 Thu	—	unknown	—	50.1° 13:05	9.23	83%	126.6°
2042-10-03 Fri	—	unknown	—	50.1° 13:05	9.28	73%	112.3°
2042-10-04 Sat	—	unknown	—	50.1° 13:00	9.33	63%	98.4°
2042-10-05 Sun	—	unknown	—	50.1° 12:55	9.38	52%	84.9°
2042-10-06 Mon	—	unknown	—	50.1° 12:50	9.42	41%	71.9°
2042-10-07 Tue	—	unknown	—	50.1° 12:50	9.47	32%	59.1°
2042-10-08 Wed	—	unknown	—	50.1° 12:45	9.51	23%	46.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-09-09&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.