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.

2030-04-19astronomy score per night — click a bar for that night2030-05-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-04-19 Fri	—	unknown	—	42.9° 17:05	7.06	95%	139.4°
2030-04-20 Sat	—	unknown	—	42.9° 17:05	7.0	89%	148.2°
2030-04-21 Sun	—	unknown	—	42.9° 17:00	6.94	80%	152.0°
2030-04-22 Mon	—	unknown	—	42.9° 16:55	6.89	70%	149.1°
2030-04-23 Tue	—	unknown	—	42.9° 16:50	6.83	59%	141.6°
2030-04-24 Wed	—	unknown	—	42.9° 16:45	6.77	48%	131.8°
2030-04-25 Thu	—	unknown	—	42.9° 16:45	6.71	38%	121.1°
2030-04-26 Fri	—	unknown	—	42.9° 16:40	6.65	28%	110.1°
2030-04-27 Sat	—	unknown	—	42.9° 16:35	6.59	20%	99.0°
2030-04-28 Sun	—	unknown	—	42.9° 16:30	6.54	12%	88.1°
2030-04-29 Mon	—	unknown	—	42.9° 16:30	6.48	7%	77.3°
2030-04-30 Tue	—	unknown	—	42.9° 16:25	6.42	3%	66.8°
2030-05-01 Wed	—	unknown	—	42.9° 16:20	6.36	0%	56.7°
2030-05-02 Thu	—	unknown	—	42.9° 16:15	6.3	0%	47.2°
2030-05-03 Fri	—	unknown	—	42.9° 16:10	6.25	2%	38.6°
2030-05-04 Sat	—	unknown	—	42.9° 16:10	6.19	5%	31.9°
2030-05-05 Sun	—	unknown	—	42.9° 16:05	6.13	10%	28.2°
2030-05-06 Mon	—	unknown	—	42.9° 16:00	6.07	16%	28.9°
2030-05-07 Tue	—	unknown	—	42.9° 15:55	6.02	24%	33.8°
2030-05-08 Wed	—	unknown	—	42.9° 15:50	5.96	32%	41.5°
2030-05-09 Thu	—	unknown	—	42.9° 15:50	5.9	42%	50.9°
2030-05-10 Fri	—	unknown	—	42.9° 15:45	5.85	52%	61.4°
2030-05-11 Sat	—	unknown	—	42.9° 15:40	5.79	63%	72.6°
2030-05-12 Sun	—	unknown	—	42.9° 15:35	5.74	73%	84.6°
2030-05-13 Mon	—	unknown	—	42.9° 15:35	5.68	82%	97.0°
2030-05-14 Tue	—	unknown	—	42.9° 15:30	5.63	90%	109.7°
2030-05-15 Wed	—	unknown	—	42.9° 15:25	5.58	96%	122.4°
2030-05-16 Thu	—	unknown	—	42.9° 15:20	5.52	100%	134.5°
2030-05-17 Fri	—	unknown	—	42.9° 15:15	5.47	100%	144.8°
2030-05-18 Sat	—	unknown	—	42.9° 15:15	5.42	97%	151.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-04-19&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.