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.

2028-09-05astronomy score per night — click a bar for that night2028-10-04

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-09-05 Tue	—	unknown	—	50.2° 14:50	7.86	96%	170.3°
2028-09-06 Wed	—	unknown	—	50.2° 14:45	7.92	92%	165.3°
2028-09-07 Thu	—	unknown	—	50.2° 14:45	7.97	86%	155.0°
2028-09-08 Fri	—	unknown	—	50.2° 14:40	8.03	79%	143.7°
2028-09-09 Sat	—	unknown	—	50.2° 14:35	8.08	71%	131.8°
2028-09-10 Sun	—	unknown	—	50.2° 14:30	8.13	61%	119.6°
2028-09-11 Mon	—	unknown	—	50.2° 14:30	8.19	51%	107.1°
2028-09-12 Tue	—	unknown	—	50.2° 14:25	8.24	41%	94.1°
2028-09-13 Wed	—	unknown	—	50.2° 14:20	8.29	30%	80.8°
2028-09-14 Thu	—	unknown	—	50.2° 14:15	8.35	20%	66.9°
2028-09-15 Fri	—	unknown	—	50.2° 14:10	8.4	12%	52.7°
2028-09-16 Sat	—	unknown	—	50.2° 14:10	8.45	5%	38.3°
2028-09-17 Sun	—	unknown	—	50.2° 14:05	8.5	1%	24.0°
2028-09-18 Mon	—	unknown	—	50.2° 14:00	8.56	0%	11.8°
2028-09-19 Tue	—	unknown	—	50.2° 13:55	8.61	2%	12.7°
2028-09-20 Wed	—	unknown	—	50.2° 13:50	8.66	7%	25.2°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-09-05&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.