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.

2039-04-25astronomy score per night — click a bar for that night2039-05-24

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-25 Mon	—	unknown	—	42.9° 16:45	6.72	6%	32.9°
2039-04-26 Tue	—	unknown	—	42.9° 16:40	6.66	11%	29.0°
2039-04-27 Wed	—	unknown	—	42.9° 16:35	6.6	17%	29.3°
2039-04-28 Thu	—	unknown	—	42.9° 16:35	6.55	25%	33.6°
2039-04-29 Fri	—	unknown	—	42.9° 16:30	6.49	34%	40.9°
2039-04-30 Sat	—	unknown	—	42.9° 16:25	6.43	43%	49.9°
2039-05-01 Sun	—	unknown	—	42.9° 16:20	6.37	53%	60.0°
2039-05-02 Mon	—	unknown	—	42.9° 16:15	6.31	64%	71.0°
2039-05-03 Tue	—	unknown	—	42.9° 16:15	6.26	74%	82.6°
2039-05-04 Wed	—	unknown	—	42.9° 16:10	6.2	83%	94.7°
2039-05-05 Thu	—	unknown	—	42.9° 16:05	6.14	91%	107.1°
2039-05-06 Fri	—	unknown	—	42.9° 16:00	6.08	96%	119.6°
2039-05-07 Sat	—	unknown	—	42.9° 15:55	6.03	100%	131.7°
2039-05-08 Sun	—	unknown	—	42.9° 15:55	5.97	100%	142.4°
2039-05-09 Mon	—	unknown	—	42.9° 15:50	5.91	97%	149.7°
2039-05-10 Tue	—	unknown	—	42.9° 15:45	5.86	91%	151.0°
2039-05-11 Wed	—	unknown	—	42.9° 15:40	5.8	83%	145.9°
2039-05-12 Thu	—	unknown	—	42.9° 15:40	5.75	74%	136.8°
2039-05-13 Fri	—	unknown	—	42.9° 15:35	5.69	63%	126.1°
2039-05-14 Sat	—	unknown	—	42.9° 15:30	5.64	52%	114.9°
2039-05-15 Sun	—	unknown	—	42.9° 15:25	5.59	42%	103.6°
2039-05-16 Mon	—	unknown	—	42.9° 15:20	5.53	32%	92.4°
2039-05-17 Tue	—	unknown	—	42.9° 15:20	5.48	23%	81.4°
2039-05-18 Wed	—	unknown	—	42.9° 15:15	5.43	15%	70.7°
2039-05-19 Thu	—	unknown	—	42.9° 15:10	5.38	9%	60.4°
2039-05-20 Fri	—	unknown	—	42.9° 15:05	5.33	4%	50.7°
2039-05-21 Sat	—	unknown	—	42.9° 15:00	5.28	1%	41.8°
2039-05-22 Sun	—	unknown	—	42.9° 15:00	5.23	0%	34.4°
2039-05-23 Mon	—	unknown	—	42.9° 14:55	5.18	1%	29.7°
2039-05-24 Tue	—	unknown	—	42.9° 14:50	5.13	3%	28.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-25&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.