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.

2028-09-21astronomy score per night — click a bar for that night2028-10-20

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-09-21 Thu	—	unknown	—	50.2° 13:50	8.71	14%	39.0°
2028-09-22 Fri	—	unknown	—	50.2° 13:45	8.76	23%	52.8°
2028-09-23 Sat	—	unknown	—	50.2° 13:40	8.81	33%	66.3°
2028-09-24 Sun	—	unknown	—	50.2° 13:35	8.86	44%	79.3°
2028-09-25 Mon	—	unknown	—	50.2° 13:35	8.91	54%	92.0°
2028-09-26 Tue	—	unknown	—	50.2° 13:30	8.96	64%	104.3°
2028-09-27 Wed	—	unknown	—	50.2° 13:25	9.01	73%	116.3°
2028-09-28 Thu	—	unknown	—	50.2° 13:20	9.06	81%	128.2°
2028-09-29 Fri	—	unknown	—	50.2° 13:15	9.11	88%	139.7°
2028-09-30 Sat	—	unknown	—	50.2° 13:15	9.16	93%	151.1°
2028-10-01 Sun	—	unknown	—	50.2° 13:10	9.2	97%	161.7°
2028-10-02 Mon	—	unknown	—	50.2° 13:05	9.25	99%	169.7°
2028-10-03 Tue	—	unknown	—	50.2° 13:00	9.3	100%	167.4°
2028-10-04 Wed	—	unknown	—	50.2° 12:55	9.35	98%	157.8°
2028-10-05 Thu	—	unknown	—	50.2° 12:55	9.39	95%	146.6°
2028-10-06 Fri	—	unknown	—	50.2° 12:50	9.44	90%	134.8°
2028-10-07 Sat	—	unknown	—	50.2° 12:45	9.49	84%	122.7°
2028-10-08 Sun	—	unknown	—	50.2° 12:40	9.53	76%	110.4°
2028-10-09 Mon	—	unknown	—	50.2° 12:40	9.58	66%	97.7°
2028-10-10 Tue	—	unknown	—	50.2° 12:35	9.62	56%	84.8°
2028-10-11 Wed	—	unknown	—	50.2° 12:30	9.67	45%	71.6°
2028-10-12 Thu	—	unknown	—	50.2° 12:25	9.71	34%	58.0°
2028-10-13 Fri	—	unknown	—	50.2° 12:20	9.76	24%	44.1°
2028-10-14 Sat	—	unknown	—	50.2° 12:20	9.8	15%	30.1°
2028-10-15 Sun	—	unknown	—	50.2° 12:15	9.84	7%	16.7°
2028-10-16 Mon	—	unknown	—	50.2° 12:10	9.89	2%	9.8°
2028-10-17 Tue	—	unknown	—	50.2° 12:05	9.93	0%	19.0°
2028-10-18 Wed	—	unknown	—	50.2° 12:00	9.97	1%	32.7°
2028-10-19 Thu	—	unknown	—	50.2° 11:55	10.01	5%	46.9°
2028-10-20 Fri	—	unknown	—	50.2° 11:50	10.06	11%	60.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-09-21&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.