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.

2030-04-21astronomy score per night — click a bar for that night2030-05-20

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2030-05-12 Sun	—	unknown	—	72.5° 13:50	5.74	73%	110.2°
2030-05-13 Mon	—	unknown	—	72.5° 13:45	5.68	82%	124.2°
2030-05-14 Tue	—	unknown	—	72.5° 13:40	5.63	90%	138.7°
2030-05-15 Wed	—	unknown	—	72.5° 13:35	5.58	96%	153.5°
2030-05-16 Thu	—	unknown	—	72.5° 13:35	5.52	100%	168.5°
2030-05-17 Fri	—	unknown	—	72.5° 13:30	5.47	100%	175.2°
2030-05-18 Sat	—	unknown	—	72.5° 13:25	5.42	97%	160.6°
2030-05-19 Sun	—	unknown	—	72.5° 13:20	5.37	91%	145.7°
2030-05-20 Mon	—	unknown	—	72.5° 13:15	5.32	83%	131.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-04-21&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.