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.

2031-08-31astronomy score per night — click a bar for that night2031-09-29

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2031-09-16 Tue	—	unknown	—	50.2° 14:10	8.41	0%	13.6°
2031-09-17 Wed	—	unknown	—	50.2° 14:05	8.47	2%	8.5°
2031-09-18 Thu	—	unknown	—	50.2° 14:05	8.52	5%	17.0°
2031-09-19 Fri	—	unknown	—	50.2° 14:00	8.57	10%	29.2°
2031-09-20 Sat	—	unknown	—	50.2° 13:55	8.62	18%	42.2°
2031-09-21 Sun	—	unknown	—	50.2° 13:50	8.67	27%	55.5°
2031-09-22 Mon	—	unknown	—	50.2° 13:45	8.72	37%	69.1°
2031-09-23 Tue	—	unknown	—	50.2° 13:45	8.77	48%	82.9°
2031-09-24 Wed	—	unknown	—	50.2° 13:40	8.82	60%	96.9°
2031-09-25 Thu	—	unknown	—	50.2° 13:35	8.87	71%	111.0°
2031-09-26 Fri	—	unknown	—	50.2° 13:30	8.92	81%	125.2°
2031-09-27 Sat	—	unknown	—	50.2° 13:30	8.97	89%	139.4°
2031-09-28 Sun	—	unknown	—	50.2° 13:25	9.02	95%	153.2°
2031-09-29 Mon	—	unknown	—	50.2° 13:20	9.07	99%	166.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-08-31&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.