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.

2031-04-15astronomy score per night — click a bar for that night2031-05-14

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-04-15 Tue	—	unknown	—	72.5° 15:35	7.31	34%	105.4°
2031-04-16 Wed	—	unknown	—	72.5° 15:30	7.25	24%	91.6°
2031-04-17 Thu	—	unknown	—	72.5° 15:30	7.19	16%	78.0°
2031-04-18 Fri	—	unknown	—	72.5° 15:25	7.13	8%	64.5°
2031-04-19 Sat	—	unknown	—	72.5° 15:20	7.07	4%	51.3°
2031-04-20 Sun	—	unknown	—	72.5° 15:15	7.02	1%	38.3°
2031-04-21 Mon	—	unknown	—	72.5° 15:10	6.96	0%	25.6°
2031-04-22 Tue	—	unknown	—	72.5° 15:10	6.9	2%	13.3°
2031-04-23 Wed	—	unknown	—	72.5° 15:05	6.84	5%	4.3°
2031-04-24 Thu	—	unknown	—	72.5° 15:00	6.78	10%	12.7°
2031-04-25 Fri	—	unknown	—	72.5° 14:55	6.72	16%	24.3°
2031-04-26 Sat	—	unknown	—	72.5° 14:50	6.67	24%	36.1°
2031-04-27 Sun	—	unknown	—	72.5° 14:50	6.61	32%	47.8°
2031-04-28 Mon	—	unknown	—	72.5° 14:45	6.55	42%	59.6°
2031-04-29 Tue	—	unknown	—	72.5° 14:40	6.49	51%	71.5°
2031-04-30 Wed	—	unknown	—	72.5° 14:35	6.43	61%	83.6°
2031-05-01 Thu	—	unknown	—	72.5° 14:30	6.38	70%	96.0°
2031-05-02 Fri	—	unknown	—	72.5° 14:30	6.32	79%	108.7°
2031-05-03 Sat	—	unknown	—	72.5° 14:25	6.26	87%	121.8°
2031-05-04 Sun	—	unknown	—	72.5° 14:20	6.2	94%	135.3°
2031-05-05 Mon	—	unknown	—	72.5° 14:15	6.14	98%	149.1°
2031-05-06 Tue	—	unknown	—	72.5° 14:15	6.09	100%	163.2°
2031-05-07 Wed	—	unknown	—	72.5° 14:10	6.03	99%	175.4°
2031-05-08 Thu	—	unknown	—	72.5° 14:05	5.97	96%	166.2°
2031-05-09 Fri	—	unknown	—	72.5° 14:00	5.92	89%	151.8°
2031-05-10 Sat	—	unknown	—	72.5° 13:55	5.86	81%	137.3°
2031-05-11 Sun	—	unknown	—	72.5° 13:55	5.81	71%	122.8°
2031-05-12 Mon	—	unknown	—	72.5° 13:50	5.75	60%	108.6°
2031-05-13 Tue	—	unknown	—	72.5° 13:45	5.7	48%	94.7°
2031-05-14 Wed	—	unknown	—	72.5° 13:40	5.64	38%	81.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-04-15&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.