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.

2028-04-23astronomy score per night — click a bar for that night2028-05-22

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-04-23 Sun	—	unknown	—	72.5° 15:00	6.8	1%	35.7°
2028-04-24 Mon	—	unknown	—	72.5° 14:55	6.74	0%	23.2°
2028-04-25 Tue	—	unknown	—	72.5° 14:55	6.68	1%	10.5°
2028-04-26 Wed	—	unknown	—	72.5° 14:50	6.62	5%	2.4°
2028-04-27 Thu	—	unknown	—	72.5° 14:45	6.57	10%	15.6°
2028-04-28 Fri	—	unknown	—	72.5° 14:40	6.51	18%	28.9°
2028-04-29 Sat	—	unknown	—	72.5° 14:35	6.45	27%	42.5°
2028-04-30 Sun	—	unknown	—	72.5° 14:35	6.39	37%	56.2°
2028-05-01 Mon	—	unknown	—	72.5° 14:30	6.33	48%	70.2°
2028-05-02 Tue	—	unknown	—	72.5° 14:25	6.28	59%	84.3°
2028-05-03 Wed	—	unknown	—	72.5° 14:20	6.22	70%	98.6°
2028-05-04 Thu	—	unknown	—	72.5° 14:20	6.16	80%	113.0°
2028-05-05 Fri	—	unknown	—	72.5° 14:15	6.1	89%	127.5°
2028-05-06 Sat	—	unknown	—	72.5° 14:10	6.05	95%	142.0°
2028-05-07 Sun	—	unknown	—	72.5° 14:05	5.99	99%	156.3°
2028-05-08 Mon	—	unknown	—	72.5° 14:00	5.93	100%	170.4°
2028-05-09 Tue	—	unknown	—	72.5° 14:00	5.88	98%	175.7°
2028-05-10 Wed	—	unknown	—	72.5° 13:55	5.82	95%	162.2°
2028-05-11 Thu	—	unknown	—	72.5° 13:50	5.77	89%	149.1°
2028-05-12 Fri	—	unknown	—	72.5° 13:45	5.71	82%	136.3°
2028-05-13 Sat	—	unknown	—	72.5° 13:40	5.66	73%	123.8°
2028-05-14 Sun	—	unknown	—	72.5° 13:40	5.6	64%	111.6°
2028-05-15 Mon	—	unknown	—	72.5° 13:35	5.55	55%	99.6°
2028-05-16 Tue	—	unknown	—	72.5° 13:30	5.5	46%	87.8°
2028-05-17 Wed	—	unknown	—	72.5° 13:25	5.45	36%	75.9°
2028-05-18 Thu	—	unknown	—	72.5° 13:25	5.39	27%	64.0°
2028-05-19 Fri	—	unknown	—	72.5° 13:20	5.34	19%	52.0°
2028-05-20 Sat	—	unknown	—	72.5° 13:15	5.29	12%	39.8°
2028-05-21 Sun	—	unknown	—	72.5° 13:10	5.24	6%	27.3°
2028-05-22 Mon	—	unknown	—	72.5° 13:05	5.2	2%	14.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-04-23&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.