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.

2037-09-17astronomy score per night — click a bar for that night2037-10-16

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-09-17 Thu	—	unknown	—	50.2° 14:05	8.49	65%	96.9°
2037-09-18 Fri	—	unknown	—	50.2° 14:00	8.55	74%	109.4°
2037-09-19 Sat	—	unknown	—	50.1° 13:55	8.6	82%	121.6°
2037-09-20 Sun	—	unknown	—	50.1° 13:55	8.65	89%	133.7°
2037-09-21 Mon	—	unknown	—	50.2° 13:50	8.7	94%	145.6°
2037-09-22 Tue	—	unknown	—	50.2° 13:45	8.75	98%	157.5°
2037-09-23 Wed	—	unknown	—	50.1° 13:40	8.8	100%	169.3°
2037-09-24 Thu	—	unknown	—	50.1° 13:40	8.85	100%	178.8°
2037-09-25 Fri	—	unknown	—	50.2° 13:35	8.9	98%	167.0°
2037-09-26 Sat	—	unknown	—	50.2° 13:30	8.95	94%	155.1°
2037-09-27 Sun	—	unknown	—	50.2° 13:25	9.0	89%	143.0°
2037-09-28 Mon	—	unknown	—	50.1° 13:20	9.05	83%	130.9°
2037-09-29 Tue	—	unknown	—	50.1° 13:20	9.1	75%	118.6°
2037-09-30 Wed	—	unknown	—	50.2° 13:15	9.15	66%	106.0°
2037-10-01 Thu	—	unknown	—	50.2° 13:10	9.2	55%	93.2°
2037-10-02 Fri	—	unknown	—	50.2° 13:05	9.24	45%	80.0°
2037-10-03 Sat	—	unknown	—	50.1° 13:00	9.29	34%	66.3°
2037-10-04 Sun	—	unknown	—	50.1° 13:00	9.34	24%	52.3°
2037-10-05 Mon	—	unknown	—	50.2° 12:55	9.38	15%	37.8°
2037-10-06 Tue	—	unknown	—	50.2° 12:50	9.43	7%	22.9°
2037-10-07 Wed	—	unknown	—	50.1° 12:45	9.48	2%	7.8°
2037-10-08 Thu	—	unknown	—	50.1° 12:45	9.52	0%	7.4°
2037-10-09 Fri	—	unknown	—	50.1° 12:40	9.57	1%	22.6°
2037-10-10 Sat	—	unknown	—	50.2° 12:35	9.61	5%	37.5°
2037-10-11 Sun	—	unknown	—	50.2° 12:30	9.66	11%	52.1°
2037-10-12 Mon	—	unknown	—	50.1° 12:25	9.7	20%	66.3°
2037-10-13 Tue	—	unknown	—	50.1° 12:25	9.75	29%	79.9°
2037-10-14 Wed	—	unknown	—	50.2° 12:20	9.79	39%	93.1°
2037-10-15 Thu	—	unknown	—	50.2° 12:15	9.84	49%	105.9°
2037-10-16 Fri	—	unknown	—	50.1° 12:10	9.88	59%	118.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-09-17&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.