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.

2039-04-19astronomy score per night — click a bar for that night2039-05-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-19 Tue	—	unknown	—	79.2° 13:10	7.07	12%	48.8°
2039-04-20 Wed	—	unknown	—	79.2° 13:05	7.01	6%	38.6°
2039-04-21 Thu	—	unknown	—	79.2° 13:00	6.95	2%	29.9°
2039-04-22 Fri	—	unknown	—	79.2° 12:55	6.9	0%	24.3°
2039-04-23 Sat	—	unknown	—	79.2° 12:50	6.84	0%	23.7°
2039-04-24 Sun	—	unknown	—	79.2° 12:50	6.78	2%	28.4°
2039-04-25 Mon	—	unknown	—	79.2° 12:45	6.72	6%	36.2°
2039-04-26 Tue	—	unknown	—	79.2° 12:40	6.66	11%	45.6°
2039-04-27 Wed	—	unknown	—	79.2° 12:35	6.6	17%	55.8°
2039-04-28 Thu	—	unknown	—	79.2° 12:30	6.55	25%	66.4°
2039-04-29 Fri	—	unknown	—	79.2° 12:30	6.49	34%	77.3°
2039-04-30 Sat	—	unknown	—	79.2° 12:25	6.43	43%	88.5°
2039-05-01 Sun	—	unknown	—	79.2° 12:20	6.37	53%	100.0°
2039-05-02 Mon	—	unknown	—	79.2° 12:15	6.31	64%	111.8°
2039-05-03 Tue	—	unknown	—	79.2° 12:15	6.26	74%	123.7°
2039-05-04 Wed	—	unknown	—	79.2° 12:10	6.2	83%	135.5°
2039-05-05 Thu	—	unknown	—	79.2° 12:05	6.14	91%	146.5°
2039-05-06 Fri	—	unknown	—	79.2° 12:00	6.08	96%	154.7°
2039-05-07 Sat	—	unknown	—	79.2° 11:55	6.03	100%	156.3°
2039-05-08 Sun	—	unknown	—	79.2° 11:50	5.97	100%	149.7°
2039-05-09 Mon	—	unknown	—	79.2° 11:45	5.91	97%	138.7°
2039-05-10 Tue	—	unknown	—	79.2° 11:40	5.86	91%	126.0°
2039-05-11 Wed	—	unknown	—	79.2° 11:35	5.8	83%	112.8°
2039-05-12 Thu	—	unknown	—	79.2° 11:35	5.75	74%	99.7°
2039-05-13 Fri	—	unknown	—	79.2° 11:30	5.69	63%	86.9°
2039-05-14 Sat	—	unknown	—	79.2° 11:25	5.64	52%	74.5°
2039-05-15 Sun	—	unknown	—	79.2° 11:20	5.59	42%	62.6°
2039-05-16 Mon	—	unknown	—	79.2° 11:20	5.53	32%	51.4°
2039-05-17 Tue	—	unknown	—	79.2° 11:15	5.48	23%	40.9°
2039-05-18 Wed	—	unknown	—	79.2° 11:10	5.43	15%	31.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-19&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.