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.

2039-04-07astronomy score per night — click a bar for that night2039-05-06

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-07 Thu	—	unknown	—	79.2° 13:55	7.76	98%	140.5°
2039-04-08 Fri	—	unknown	—	79.2° 13:50	7.7	100%	150.8°
2039-04-09 Sat	—	unknown	—	79.2° 13:45	7.64	99%	156.5°
2039-04-10 Sun	—	unknown	—	79.2° 13:45	7.59	95%	154.2°
2039-04-11 Mon	—	unknown	—	79.2° 13:40	7.53	89%	145.3°
2039-04-12 Tue	—	unknown	—	79.2° 13:35	7.47	80%	133.7°
2039-04-13 Wed	—	unknown	—	79.2° 13:30	7.42	70%	121.2°
2039-04-14 Thu	—	unknown	—	79.2° 13:25	7.36	59%	108.5°
2039-04-15 Fri	—	unknown	—	79.2° 13:25	7.3	48%	95.9°
2039-04-16 Sat	—	unknown	—	79.2° 13:20	7.24	37%	83.5°
2039-04-17 Sun	—	unknown	—	79.2° 13:15	7.19	27%	71.5°
2039-04-18 Mon	—	unknown	—	79.2° 13:10	7.13	19%	59.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-07&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.