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.

2031-09-13astronomy score per night — click a bar for that night2031-10-12

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2031-09-30 Tue	—	unknown	—	50.2° 13:15	9.12	100%	171.2°
2031-10-01 Wed	—	unknown	—	50.2° 13:10	9.17	98%	161.4°
2031-10-02 Thu	—	unknown	—	50.2° 13:10	9.22	95%	148.9°
2031-10-03 Fri	—	unknown	—	50.2° 13:05	9.27	89%	136.1°
2031-10-04 Sat	—	unknown	—	50.2° 13:00	9.31	82%	123.6°
2031-10-05 Sun	—	unknown	—	50.2° 12:55	9.36	73%	111.4°
2031-10-06 Mon	—	unknown	—	50.2° 12:50	9.41	64%	99.4°
2031-10-07 Tue	—	unknown	—	50.2° 12:50	9.45	55%	87.5°
2031-10-08 Wed	—	unknown	—	50.2° 12:45	9.5	46%	75.8°
2031-10-09 Thu	—	unknown	—	50.2° 12:40	9.54	36%	64.1°
2031-10-10 Fri	—	unknown	—	50.2° 12:35	9.59	27%	52.4°
2031-10-11 Sat	—	unknown	—	50.2° 12:35	9.64	19%	40.6°
2031-10-12 Sun	—	unknown	—	50.2° 12:30	9.68	12%	28.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-09-13&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.