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.

2039-08-13astronomy score per night — click a bar for that night2039-09-11

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-08-13 Sat	—	unknown	—	50.1° 16:25	6.52	30%	111.8°
2039-08-14 Sun	—	unknown	—	50.1° 16:20	6.58	22%	99.9°
2039-08-15 Mon	—	unknown	—	50.1° 16:15	6.63	15%	87.9°
2039-08-16 Tue	—	unknown	—	50.1° 16:15	6.69	9%	75.8°
2039-08-17 Wed	—	unknown	—	50.1° 16:10	6.75	4%	63.5°
2039-08-18 Thu	—	unknown	—	50.1° 16:05	6.81	1%	50.9°
2039-08-19 Fri	—	unknown	—	50.1° 16:00	6.86	0%	38.1°
2039-08-20 Sat	—	unknown	—	50.1° 15:55	6.92	1%	25.1°
2039-08-21 Sun	—	unknown	—	50.1° 15:55	6.98	5%	11.8°
2039-08-22 Mon	—	unknown	—	50.1° 15:50	7.04	11%	1.7°
2039-08-23 Tue	—	unknown	—	50.1° 15:45	7.09	18%	15.3°
2039-08-24 Wed	—	unknown	—	50.1° 15:40	7.15	28%	29.2°
2039-08-25 Thu	—	unknown	—	50.1° 15:40	7.21	38%	43.1°
2039-08-26 Fri	—	unknown	—	50.1° 15:35	7.26	50%	57.2°
2039-08-27 Sat	—	unknown	—	50.1° 15:30	7.32	61%	71.4°
2039-08-28 Sun	—	unknown	—	50.1° 15:25	7.38	72%	85.6°
2039-08-29 Mon	—	unknown	—	50.1° 15:20	7.43	82%	99.9°
2039-08-30 Tue	—	unknown	—	50.1° 15:20	7.49	90%	114.2°
2039-08-31 Wed	—	unknown	—	50.1° 15:15	7.55	95%	128.3°
2039-09-01 Thu	—	unknown	—	50.1° 15:10	7.6	99%	142.3°
2039-09-02 Fri	—	unknown	—	50.1° 15:05	7.66	100%	156.1°
2039-09-03 Sat	—	unknown	—	50.1° 15:00	7.71	98%	169.6°
2039-09-04 Sun	—	unknown	—	50.1° 15:00	7.77	95%	177.3°
2039-09-05 Mon	—	unknown	—	50.1° 14:55	7.82	89%	164.4°
2039-09-06 Tue	—	unknown	—	50.1° 14:50	7.88	82%	151.9°
2039-09-07 Wed	—	unknown	—	50.1° 14:45	7.93	74%	139.7°
2039-09-08 Thu	—	unknown	—	50.1° 14:45	7.99	65%	127.6°
2039-09-09 Fri	—	unknown	—	50.1° 14:40	8.04	56%	115.7°
2039-09-10 Sat	—	unknown	—	50.1° 14:35	8.1	47%	103.9°
2039-09-11 Sun	—	unknown	—	50.1° 14:30	8.15	37%	92.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-08-13&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.