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.

2039-09-18astronomy score per night — click a bar for that night2039-10-17

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-09-18 Sun	—	unknown	—	50.1° 14:05	8.52	1%	2.6°
2039-09-19 Mon	—	unknown	—	50.1° 14:00	8.57	3%	11.3°
2039-09-20 Tue	—	unknown	—	50.1° 13:55	8.62	8%	25.4°
2039-09-21 Wed	—	unknown	—	50.1° 13:50	8.68	16%	39.6°
2039-09-22 Thu	—	unknown	—	50.1° 13:50	8.73	25%	53.9°
2039-09-23 Fri	—	unknown	—	50.1° 13:45	8.78	36%	68.2°
2039-09-24 Sat	—	unknown	—	50.1° 13:40	8.83	47%	82.4°
2039-09-25 Sun	—	unknown	—	50.1° 13:35	8.88	58%	96.5°
2039-09-26 Mon	—	unknown	—	50.1° 13:30	8.93	69%	110.5°
2039-09-27 Tue	—	unknown	—	50.1° 13:30	8.98	79%	124.3°
2039-09-28 Wed	—	unknown	—	50.1° 13:25	9.03	87%	138.0°
2039-09-29 Thu	—	unknown	—	50.1° 13:20	9.08	94%	151.6°
2039-09-30 Fri	—	unknown	—	50.1° 13:15	9.12	98%	165.0°
2039-10-01 Sat	—	unknown	—	50.1° 13:10	9.17	100%	178.1°
2039-10-02 Sun	—	unknown	—	50.1° 13:10	9.22	100%	169.0°
2039-10-03 Mon	—	unknown	—	50.1° 13:05	9.27	97%	156.3°
2039-10-04 Tue	—	unknown	—	50.1° 13:00	9.32	93%	143.9°
2039-10-05 Wed	—	unknown	—	50.1° 12:55	9.36	87%	131.8°
2039-10-06 Thu	—	unknown	—	50.1° 12:50	9.41	80%	119.7°
2039-10-07 Fri	—	unknown	—	50.1° 12:50	9.46	72%	107.9°
2039-10-08 Sat	—	unknown	—	50.1° 12:45	9.5	64%	96.0°
2039-10-09 Sun	—	unknown	—	50.1° 12:40	9.55	54%	84.2°
2039-10-10 Mon	—	unknown	—	50.1° 12:35	9.59	45%	72.2°
2039-10-11 Tue	—	unknown	—	50.1° 12:35	9.64	35%	60.0°
2039-10-12 Wed	—	unknown	—	50.1° 12:30	9.68	26%	47.6°
2039-10-13 Thu	—	unknown	—	50.1° 12:25	9.73	18%	34.8°
2039-10-14 Fri	—	unknown	—	50.1° 12:20	9.77	10%	21.7°
2039-10-15 Sat	—	unknown	—	50.1° 12:15	9.81	5%	8.1°
2039-10-16 Sun	—	unknown	—	50.1° 12:15	9.86	1%	5.8°
2039-10-17 Mon	—	unknown	—	50.1° 12:10	9.9	0%	20.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-09-18&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.