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.

2027-09-16astronomy score per night — click a bar for that night2027-10-15

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-09-16 Thu	—	unknown	—	50.2° 14:10	8.41	99%	171.0°
2027-09-17 Fri	—	unknown	—	50.2° 14:05	8.46	96%	165.1°
2027-09-18 Sat	—	unknown	—	50.2° 14:05	8.52	91%	153.9°
2027-09-19 Sun	—	unknown	—	50.2° 14:00	8.57	84%	141.6°
2027-09-20 Mon	—	unknown	—	50.2° 13:55	8.62	76%	128.8°
2027-09-21 Tue	—	unknown	—	50.2° 13:50	8.67	66%	115.7°
2027-09-22 Wed	—	unknown	—	50.2° 13:45	8.72	56%	102.3°
2027-09-23 Thu	—	unknown	—	50.2° 13:45	8.77	44%	88.6°
2027-09-24 Fri	—	unknown	—	50.2° 13:40	8.82	33%	74.6°
2027-09-25 Sat	—	unknown	—	50.2° 13:35	8.87	23%	60.4°
2027-09-26 Sun	—	unknown	—	50.2° 13:30	8.92	14%	46.1°
2027-09-27 Mon	—	unknown	—	50.2° 13:30	8.97	7%	31.9°
2027-09-28 Tue	—	unknown	—	50.2° 13:25	9.02	2%	18.3°
2027-09-29 Wed	—	unknown	—	50.2° 13:20	9.07	0%	9.1°
2027-09-30 Thu	—	unknown	—	50.2° 13:15	9.12	1%	15.7°
2027-10-01 Fri	—	unknown	—	50.2° 13:10	9.17	4%	28.4°
2027-10-02 Sat	—	unknown	—	50.2° 13:10	9.22	10%	41.5°
2027-10-03 Sun	—	unknown	—	50.2° 13:05	9.26	17%	54.5°
2027-10-04 Mon	—	unknown	—	50.2° 13:00	9.31	26%	67.1°
2027-10-05 Tue	—	unknown	—	50.2° 12:55	9.36	35%	79.4°
2027-10-06 Wed	—	unknown	—	50.2° 12:50	9.4	44%	91.5°
2027-10-07 Thu	—	unknown	—	50.2° 12:50	9.45	54%	103.3°
2027-10-08 Fri	—	unknown	—	50.2° 12:45	9.5	63%	115.0°
2027-10-09 Sat	—	unknown	—	50.2° 12:40	9.54	72%	126.7°
2027-10-10 Sun	—	unknown	—	50.2° 12:35	9.59	80%	138.3°
2027-10-11 Mon	—	unknown	—	50.2° 12:35	9.63	87%	149.8°
2027-10-12 Tue	—	unknown	—	50.2° 12:30	9.68	93%	161.0°
2027-10-13 Wed	—	unknown	—	50.2° 12:25	9.72	97%	170.0°
2027-10-14 Thu	—	unknown	—	50.2° 12:20	9.77	99%	167.9°
2027-10-15 Fri	—	unknown	—	50.2° 12:15	9.81	100%	157.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-09-16&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.