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.

2035-09-16astronomy score per night — click a bar for that night2035-10-15

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-09-16 Sun	—	unknown	—	50.2° 14:10	8.42	100%	159.6°
2035-09-17 Mon	—	unknown	—	50.2° 14:05	8.47	100%	172.5°
2035-09-18 Tue	—	unknown	—	50.2° 14:05	8.52	98%	173.5°
2035-09-19 Wed	—	unknown	—	50.2° 14:00	8.57	94%	160.2°
2035-09-20 Thu	—	unknown	—	50.2° 13:55	8.62	87%	146.5°
2035-09-21 Fri	—	unknown	—	50.2° 13:50	8.67	79%	132.6°
2035-09-22 Sat	—	unknown	—	50.2° 13:45	8.73	69%	118.6°
2035-09-23 Sun	—	unknown	—	50.2° 13:45	8.78	58%	104.5°
2035-09-24 Mon	—	unknown	—	50.2° 13:40	8.83	46%	90.4°
2035-09-25 Tue	—	unknown	—	50.2° 13:35	8.88	35%	76.2°
2035-09-26 Wed	—	unknown	—	50.2° 13:30	8.93	25%	62.1°
2035-09-27 Thu	—	unknown	—	50.2° 13:30	8.98	16%	47.9°
2035-09-28 Fri	—	unknown	—	50.2° 13:25	9.02	8%	33.9°
2035-09-29 Sat	—	unknown	—	50.2° 13:20	9.07	3%	20.1°
2035-09-30 Sun	—	unknown	—	50.2° 13:15	9.12	0%	6.6°
2035-10-01 Mon	—	unknown	—	50.2° 13:10	9.17	0%	7.5°
2035-10-02 Tue	—	unknown	—	50.2° 13:10	9.22	2%	20.5°
2035-10-03 Wed	—	unknown	—	50.2° 13:05	9.27	6%	33.3°
2035-10-04 Thu	—	unknown	—	50.2° 13:00	9.31	12%	45.8°
2035-10-05 Fri	—	unknown	—	50.2° 12:55	9.36	19%	58.1°
2035-10-06 Sat	—	unknown	—	50.2° 12:50	9.41	27%	70.2°
2035-10-07 Sun	—	unknown	—	50.2° 12:50	9.45	36%	82.1°
2035-10-08 Mon	—	unknown	—	50.2° 12:45	9.5	45%	93.9°
2035-10-09 Tue	—	unknown	—	50.2° 12:40	9.55	55%	105.7°
2035-10-10 Wed	—	unknown	—	50.2° 12:35	9.59	64%	117.7°
2035-10-11 Thu	—	unknown	—	50.2° 12:35	9.64	73%	129.8°
2035-10-12 Fri	—	unknown	—	50.2° 12:30	9.68	81%	142.1°
2035-10-13 Sat	—	unknown	—	50.2° 12:25	9.73	89%	154.8°
2035-10-14 Sun	—	unknown	—	50.2° 12:20	9.77	94%	167.7°
2035-10-15 Mon	—	unknown	—	50.2° 12:15	9.81	98%	177.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-09-16&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.