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.

2027-07-21astronomy score per night — click a bar for that night2027-08-19

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-07-21 Wed	—	unknown	—	42.9° 11:00	5.26	91%	107.1°
2027-07-22 Thu	—	unknown	—	42.9° 10:55	5.31	84%	97.1°
2027-07-23 Fri	—	unknown	—	42.9° 10:50	5.36	77%	86.9°
2027-07-24 Sat	—	unknown	—	42.9° 10:45	5.41	68%	76.6°
2027-07-25 Sun	—	unknown	—	42.9° 10:45	5.46	58%	66.3°
2027-07-26 Mon	—	unknown	—	42.9° 10:40	5.51	48%	56.1°
2027-07-27 Tue	—	unknown	—	42.9° 10:35	5.56	37%	46.5°
2027-07-28 Wed	—	unknown	—	42.9° 10:30	5.62	27%	38.4°
2027-07-29 Thu	—	unknown	—	42.9° 10:25	5.67	17%	33.3°
2027-07-30 Fri	—	unknown	—	42.9° 10:25	5.72	9%	33.3°
2027-07-31 Sat	—	unknown	—	42.9° 10:20	5.78	3%	38.7°
2027-08-01 Sun	—	unknown	—	42.9° 10:15	5.83	0%	48.0°
2027-08-02 Mon	—	unknown	—	42.9° 10:10	5.89	0%	59.3°
2027-08-03 Tue	—	unknown	—	42.9° 10:05	5.94	4%	71.4°
2027-08-04 Wed	—	unknown	—	42.9° 10:05	6.0	9%	83.8°
2027-08-05 Thu	—	unknown	—	42.9° 10:00	6.06	17%	96.0°
2027-08-06 Fri	—	unknown	—	42.9° 09:55	6.11	26%	107.7°
2027-08-07 Sat	—	unknown	—	42.9° 09:50	6.17	37%	118.7°
2027-08-08 Sun	—	unknown	—	42.9° 09:50	6.23	47%	128.6°
2027-08-09 Mon	—	unknown	—	42.9° 09:45	6.28	57%	137.2°
2027-08-10 Tue	—	unknown	—	42.9° 09:40	6.34	67%	143.7°
2027-08-11 Wed	—	unknown	—	42.9° 09:35	6.4	76%	147.1°
2027-08-12 Thu	—	unknown	—	42.9° 09:30	6.46	84%	146.7°
2027-08-13 Fri	—	unknown	—	42.9° 09:30	6.51	90%	142.8°
2027-08-14 Sat	—	unknown	—	42.9° 09:25	6.57	95%	136.3°
2027-08-15 Sun	—	unknown	—	42.9° 09:20	6.63	98%	128.2°
2027-08-16 Mon	—	unknown	—	42.9° 09:15	6.69	100%	119.2°
2027-08-17 Tue	—	unknown	—	42.9° 09:10	6.74	100%	109.6°
2027-08-18 Wed	—	unknown	—	42.9° 09:10	6.8	98%	99.6°
2027-08-19 Thu	—	unknown	—	42.9° 09:05	6.86	94%	89.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-07-21&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.