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.

2041-03-23astronomy score per night — click a bar for that night2041-04-21

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-03-23 Sat	—	unknown	—	89.8° 13:00	8.55	66%	126.5°
2041-03-24 Sun	—	unknown	—	89.6° 12:55	8.49	56%	116.5°
2041-03-25 Mon	—	unknown	—	89.6° 12:55	8.44	44%	105.6°
2041-03-26 Tue	—	unknown	—	89.7° 12:50	8.39	33%	94.1°
2041-03-27 Wed	—	unknown	—	89.8° 12:45	8.33	23%	82.2°
2041-03-28 Thu	—	unknown	—	89.7° 12:40	8.28	14%	70.4°
2041-03-29 Fri	—	unknown	—	89.5° 12:35	8.23	7%	58.9°
2041-03-30 Sat	—	unknown	—	89.6° 12:35	8.17	2%	48.5°
2041-03-31 Sun	—	unknown	—	89.8° 13:30	8.12	0%	40.2°
2041-04-01 Mon	—	unknown	—	89.8° 13:25	8.06	1%	35.4°
2041-04-02 Tue	—	unknown	—	89.7° 13:20	8.01	5%	35.4°
2041-04-03 Wed	—	unknown	—	89.5° 13:20	7.95	10%	39.9°
2041-04-04 Thu	—	unknown	—	89.7° 13:15	7.9	18%	47.3°
2041-04-05 Fri	—	unknown	—	89.8° 13:10	7.84	26%	56.1°
2041-04-06 Sat	—	unknown	—	89.8° 13:05	7.78	36%	65.6°
2041-04-07 Sun	—	unknown	—	89.6° 13:00	7.73	46%	75.4°
2041-04-08 Mon	—	unknown	—	89.6° 13:00	7.67	55%	85.2°
2041-04-09 Tue	—	unknown	—	89.7° 12:55	7.62	64%	94.9°
2041-04-10 Wed	—	unknown	—	89.8° 12:50	7.56	73%	104.6°
2041-04-11 Thu	—	unknown	—	89.7° 12:45	7.5	81%	114.0°
2041-04-12 Fri	—	unknown	—	89.5° 12:40	7.44	88%	123.0°
2041-04-13 Sat	—	unknown	—	89.6° 12:40	7.39	94%	131.4°
2041-04-14 Sun	—	unknown	—	89.8° 12:35	7.33	98%	138.6°
2041-04-15 Mon	—	unknown	—	89.8° 12:30	7.27	100%	143.6°
2041-04-16 Tue	—	unknown	—	89.7° 12:25	7.21	100%	145.2°
2041-04-17 Wed	—	unknown	—	89.5° 12:25	7.16	98%	142.9°
2041-04-18 Thu	—	unknown	—	89.7° 12:20	7.1	94%	137.0°
2041-04-19 Fri	—	unknown	—	89.8° 12:15	7.04	88%	128.7°
2041-04-20 Sat	—	unknown	—	89.8° 12:10	6.98	79%	118.9°
2041-04-21 Sun	—	unknown	—	89.6° 12:05	6.92	70%	108.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-03-23&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.