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.

2030-09-18astronomy score per night — click a bar for that night2030-10-17

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2030-09-26 Thu	—	unknown	—	50.2° 13:30	8.94	0%	12.7°
2030-09-27 Fri	—	unknown	—	50.2° 13:25	8.99	0%	10.7°
2030-09-28 Sat	—	unknown	—	50.2° 13:25	9.04	3%	21.7°
2030-09-29 Sun	—	unknown	—	50.2° 13:20	9.08	8%	35.2°
2030-09-30 Mon	—	unknown	—	50.2° 13:15	9.13	16%	49.3°
2030-10-01 Tue	—	unknown	—	50.2° 13:10	9.18	25%	63.4°
2030-10-02 Wed	—	unknown	—	50.2° 13:05	9.23	36%	77.6°
2030-10-03 Thu	—	unknown	—	50.2° 13:05	9.28	47%	91.5°
2030-10-04 Fri	—	unknown	—	50.2° 13:00	9.32	58%	105.3°
2030-10-05 Sat	—	unknown	—	50.2° 12:55	9.37	69%	118.9°
2030-10-06 Sun	—	unknown	—	50.2° 12:50	9.42	79%	132.2°
2030-10-07 Mon	—	unknown	—	50.2° 12:45	9.46	87%	145.2°
2030-10-08 Tue	—	unknown	—	50.2° 12:45	9.51	93%	157.5°
2030-10-09 Wed	—	unknown	—	50.2° 12:40	9.56	97%	168.0°
2030-10-10 Thu	—	unknown	—	50.2° 12:35	9.6	100%	169.3°
2030-10-11 Fri	—	unknown	—	50.2° 12:30	9.65	100%	160.0°
2030-10-12 Sat	—	unknown	—	50.2° 12:30	9.69	98%	148.6°
2030-10-13 Sun	—	unknown	—	50.2° 12:25	9.74	94%	136.9°
2030-10-14 Mon	—	unknown	—	50.2° 12:20	9.78	89%	125.1°
2030-10-15 Tue	—	unknown	—	50.2° 12:15	9.82	82%	113.4°
2030-10-16 Wed	—	unknown	—	50.2° 12:10	9.87	75%	101.8°
2030-10-17 Thu	—	unknown	—	50.2° 12:10	9.91	66%	90.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-09-18&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.