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.

2031-08-17astronomy score per night — click a bar for that night2031-09-15

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-08-17 Sun	—	unknown	—	50.2° 16:10	6.75	0%	44.9°
2031-08-18 Mon	—	unknown	—	50.2° 16:05	6.8	1%	33.1°
2031-08-19 Tue	—	unknown	—	50.2° 16:00	6.86	3%	21.5°
2031-08-20 Wed	—	unknown	—	50.2° 15:55	6.92	7%	11.2°
2031-08-21 Thu	—	unknown	—	50.2° 15:55	6.98	14%	9.9°
2031-08-22 Fri	—	unknown	—	50.2° 15:50	7.03	21%	19.9°
2031-08-23 Sat	—	unknown	—	50.2° 15:45	7.09	30%	32.2°
2031-08-24 Sun	—	unknown	—	50.2° 15:40	7.15	41%	45.2°
2031-08-25 Mon	—	unknown	—	50.2° 15:35	7.2	52%	58.7°
2031-08-26 Tue	—	unknown	—	50.2° 15:35	7.26	63%	72.5°
2031-08-27 Wed	—	unknown	—	50.2° 15:30	7.32	74%	86.6°
2031-08-28 Thu	—	unknown	—	50.2° 15:25	7.37	83%	101.1°
2031-08-29 Fri	—	unknown	—	50.2° 15:20	7.43	91%	115.7°
2031-08-30 Sat	—	unknown	—	50.2° 15:20	7.49	97%	130.3°
2031-08-31 Sun	—	unknown	—	50.2° 15:15	7.54	100%	144.8°
2031-09-01 Mon	—	unknown	—	50.2° 15:10	7.6	99%	158.7°
2031-09-02 Tue	—	unknown	—	50.2° 15:05	7.66	97%	170.1°
2031-09-03 Wed	—	unknown	—	50.2° 15:00	7.71	92%	167.9°
2031-09-04 Thu	—	unknown	—	50.2° 15:00	7.77	84%	156.3°
2031-09-05 Fri	—	unknown	—	50.2° 14:55	7.82	76%	143.7°
2031-09-06 Sat	—	unknown	—	50.2° 14:50	7.88	67%	131.3°
2031-09-07 Sun	—	unknown	—	50.2° 14:45	7.93	57%	119.1°
2031-09-08 Mon	—	unknown	—	50.2° 14:40	7.99	48%	107.2°
2031-09-09 Tue	—	unknown	—	50.2° 14:40	8.04	38%	95.3°
2031-09-10 Wed	—	unknown	—	50.2° 14:35	8.09	29%	83.6°
2031-09-11 Thu	—	unknown	—	50.2° 14:30	8.15	21%	71.9°
2031-09-12 Fri	—	unknown	—	50.2° 14:25	8.2	14%	60.2°
2031-09-13 Sat	—	unknown	—	50.2° 14:25	8.26	8%	48.4°
2031-09-14 Sun	—	unknown	—	50.2° 14:20	8.31	4%	36.6°
2031-09-15 Mon	—	unknown	—	50.2° 14:15	8.36	1%	24.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-08-17&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.