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.

2030-04-12astronomy score per night — click a bar for that night2030-05-11

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-04-12 Fri	—	unknown	—	72.5° 15:45	7.46	68%	74.8°
2030-04-13 Sat	—	unknown	—	72.5° 15:40	7.41	77%	88.1°
2030-04-14 Sun	—	unknown	—	72.5° 15:40	7.35	86%	101.8°
2030-04-15 Mon	—	unknown	—	72.5° 15:35	7.29	93%	115.9°
2030-04-16 Tue	—	unknown	—	72.5° 15:30	7.23	98%	130.5°
2030-04-17 Wed	—	unknown	—	72.5° 15:25	7.18	100%	145.4°
2030-04-18 Thu	—	unknown	—	72.5° 15:25	7.12	99%	160.4°
2030-04-19 Fri	—	unknown	—	72.5° 15:20	7.06	95%	175.0°
2030-04-20 Sat	—	unknown	—	72.5° 15:15	7.0	89%	169.1°
2030-04-21 Sun	—	unknown	—	72.5° 15:10	6.94	80%	154.5°
2030-04-22 Mon	—	unknown	—	72.5° 15:05	6.89	70%	140.2°
2030-04-23 Tue	—	unknown	—	72.5° 15:05	6.83	59%	126.2°
2030-04-24 Wed	—	unknown	—	72.5° 15:00	6.77	48%	112.7°
2030-04-25 Thu	—	unknown	—	72.5° 14:55	6.71	38%	99.5°
2030-04-26 Fri	—	unknown	—	72.5° 14:50	6.65	28%	86.6°
2030-04-27 Sat	—	unknown	—	72.5° 14:45	6.59	20%	74.0°
2030-04-28 Sun	—	unknown	—	72.5° 14:45	6.54	12%	61.6°
2030-04-29 Mon	—	unknown	—	72.5° 14:40	6.48	7%	49.4°
2030-04-30 Tue	—	unknown	—	72.5° 14:35	6.42	3%	37.3°
2030-05-01 Wed	—	unknown	—	72.5° 14:30	6.36	0%	25.4°
2030-05-02 Thu	—	unknown	—	72.5° 14:30	6.3	0%	13.6°
2030-05-03 Fri	—	unknown	—	72.5° 14:25	6.25	2%	3.0°
2030-05-04 Sat	—	unknown	—	72.5° 14:20	6.19	5%	10.6°
2030-05-05 Sun	—	unknown	—	72.5° 14:15	6.13	10%	22.3°
2030-05-06 Mon	—	unknown	—	72.5° 14:10	6.07	16%	34.2°
2030-05-07 Tue	—	unknown	—	72.5° 14:10	6.02	24%	46.1°
2030-05-08 Wed	—	unknown	—	72.5° 14:05	5.96	32%	58.3°
2030-05-09 Thu	—	unknown	—	72.5° 14:00	5.9	42%	70.7°
2030-05-10 Fri	—	unknown	—	72.5° 13:55	5.85	52%	83.5°
2030-05-11 Sat	—	unknown	—	72.5° 13:50	5.79	63%	96.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-04-12&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.