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.

2037-08-20astronomy score per night — click a bar for that night2037-09-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-08-20 Thu	—	unknown	—	50.2° 15:55	6.95	79%	87.4°
2037-08-21 Fri	—	unknown	—	50.2° 15:50	7.01	86%	100.0°
2037-08-22 Sat	—	unknown	—	50.1° 15:45	7.06	92%	112.4°
2037-08-23 Sun	—	unknown	—	50.2° 15:45	7.12	97%	124.6°
2037-08-24 Mon	—	unknown	—	50.2° 15:40	7.18	99%	136.7°
2037-08-25 Tue	—	unknown	—	50.2° 15:35	7.24	100%	148.7°
2037-08-26 Wed	—	unknown	—	50.1° 15:30	7.29	99%	160.6°
2037-08-27 Thu	—	unknown	—	50.1° 15:30	7.35	96%	172.4°
2037-08-28 Fri	—	unknown	—	50.2° 15:25	7.41	91%	175.8°
2037-08-29 Sat	—	unknown	—	50.2° 15:20	7.46	85%	163.9°
2037-08-30 Sun	—	unknown	—	50.2° 15:15	7.52	78%	152.0°
2037-08-31 Mon	—	unknown	—	50.1° 15:10	7.57	69%	139.9°
2037-09-01 Tue	—	unknown	—	50.1° 15:10	7.63	60%	127.7°
2037-09-02 Wed	—	unknown	—	50.2° 15:05	7.69	50%	115.1°
2037-09-03 Thu	—	unknown	—	50.2° 15:00	7.74	40%	102.2°
2037-09-04 Fri	—	unknown	—	50.2° 14:55	7.8	29%	88.9°
2037-09-05 Sat	—	unknown	—	50.1° 14:50	7.85	20%	75.2°
2037-09-06 Sun	—	unknown	—	50.1° 14:50	7.91	12%	60.9°
2037-09-07 Mon	—	unknown	—	50.2° 14:45	7.96	5%	46.2°
2037-09-08 Tue	—	unknown	—	50.2° 14:40	8.02	1%	31.2°
2037-09-09 Wed	—	unknown	—	50.1° 14:35	8.07	0%	16.0°
2037-09-10 Thu	—	unknown	—	50.1° 14:35	8.12	2%	0.7°
2037-09-11 Fri	—	unknown	—	50.2° 14:30	8.18	7%	14.4°
2037-09-12 Sat	—	unknown	—	50.2° 14:25	8.23	15%	29.2°
2037-09-13 Sun	—	unknown	—	50.2° 14:20	8.28	24%	43.6°
2037-09-14 Mon	—	unknown	—	50.1° 14:15	8.34	34%	57.6°
2037-09-15 Tue	—	unknown	—	50.1° 14:15	8.39	45%	71.1°
2037-09-16 Wed	—	unknown	—	50.2° 14:10	8.44	55%	84.2°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-08-20&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.