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.

2030-08-27astronomy score per night — click a bar for that night2030-09-25

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-08-27 Tue	—	unknown	—	50.2° 15:30	7.33	1%	44.8°
2030-08-28 Wed	—	unknown	—	50.2° 15:25	7.39	0%	32.1°
2030-08-29 Thu	—	unknown	—	50.2° 15:20	7.44	1%	19.7°
2030-08-30 Fri	—	unknown	—	50.2° 15:15	7.5	5%	10.1°
2030-08-31 Sat	—	unknown	—	50.2° 15:15	7.56	11%	13.8°
2030-09-01 Sun	—	unknown	—	50.2° 15:10	7.61	18%	25.8°
2030-09-02 Mon	—	unknown	—	50.2° 15:05	7.67	28%	39.2°
2030-09-03 Tue	—	unknown	—	50.2° 15:00	7.72	39%	53.0°
2030-09-04 Wed	—	unknown	—	50.2° 14:55	7.78	50%	66.9°
2030-09-05 Thu	—	unknown	—	50.2° 14:55	7.83	62%	80.8°
2030-09-06 Fri	—	unknown	—	50.2° 14:50	7.89	72%	94.7°
2030-09-07 Sat	—	unknown	—	50.2° 14:45	7.94	82%	108.6°
2030-09-08 Sun	—	unknown	—	50.2° 14:40	8.0	90%	122.3°
2030-09-09 Mon	—	unknown	—	50.2° 14:35	8.05	95%	135.8°
2030-09-10 Tue	—	unknown	—	50.2° 14:35	8.11	99%	148.9°
2030-09-11 Wed	—	unknown	—	50.2° 14:30	8.16	100%	161.2°
2030-09-12 Thu	—	unknown	—	50.2° 14:25	8.21	99%	170.1°
2030-09-13 Fri	—	unknown	—	50.2° 14:20	8.27	95%	166.7°
2030-09-14 Sat	—	unknown	—	50.2° 14:20	8.32	90%	156.2°
2030-09-15 Sun	—	unknown	—	50.2° 14:15	8.37	84%	144.6°
2030-09-16 Mon	—	unknown	—	50.2° 14:10	8.43	76%	132.9°
2030-09-17 Tue	—	unknown	—	50.2° 14:05	8.48	68%	121.3°
2030-09-18 Wed	—	unknown	—	50.2° 14:00	8.53	58%	109.6°
2030-09-19 Thu	—	unknown	—	50.2° 14:00	8.58	49%	97.9°
2030-09-20 Fri	—	unknown	—	50.2° 13:55	8.63	40%	86.1°
2030-09-21 Sat	—	unknown	—	50.2° 13:50	8.69	30%	74.2°
2030-09-22 Sun	—	unknown	—	50.2° 13:45	8.74	22%	62.0°
2030-09-23 Mon	—	unknown	—	50.2° 13:40	8.79	14%	49.6°
2030-09-24 Tue	—	unknown	—	50.2° 13:40	8.84	8%	36.9°
2030-09-25 Wed	—	unknown	—	50.2° 13:35	8.89	3%	24.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-08-27&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.