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.

2042-03-25astronomy score per night — click a bar for that night2042-04-23

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-03-25 Tue	—	unknown	—	89.7° 12:55	8.45	24%	44.9°
2042-03-26 Wed	—	unknown	—	89.8° 12:50	8.4	34%	54.4°
2042-03-27 Thu	—	unknown	—	89.7° 12:45	8.35	44%	64.7°
2042-03-28 Fri	—	unknown	—	89.6° 12:40	8.29	55%	75.2°
2042-03-29 Sat	—	unknown	—	89.6° 12:40	8.24	64%	85.7°
2042-03-30 Sun	—	unknown	—	89.8° 13:35	8.18	74%	96.0°
2042-03-31 Mon	—	unknown	—	89.8° 13:30	8.13	82%	106.0°
2042-04-01 Tue	—	unknown	—	89.7° 13:25	8.08	88%	115.7°
2042-04-02 Wed	—	unknown	—	89.5° 13:20	8.02	94%	124.9°
2042-04-03 Thu	—	unknown	—	89.7° 13:20	7.97	98%	133.3°
2042-04-04 Fri	—	unknown	—	89.8° 13:15	7.91	100%	140.3°
2042-04-05 Sat	—	unknown	—	89.8° 13:10	7.85	100%	145.2°
2042-04-06 Sun	—	unknown	—	89.6° 13:05	7.8	98%	146.9°
2042-04-07 Mon	—	unknown	—	89.5° 13:05	7.74	95%	144.9°
2042-04-08 Tue	—	unknown	—	89.7° 13:00	7.69	90%	139.6°
2042-04-09 Wed	—	unknown	—	89.8° 12:55	7.63	83%	132.0°
2042-04-10 Thu	—	unknown	—	89.7° 12:50	7.57	75%	123.0°
2042-04-11 Fri	—	unknown	—	89.6° 12:45	7.52	66%	113.0°
2042-04-12 Sat	—	unknown	—	89.6° 12:45	7.46	56%	102.3°
2042-04-13 Sun	—	unknown	—	89.8° 12:40	7.4	45%	91.2°
2042-04-14 Mon	—	unknown	—	89.8° 12:35	7.34	34%	79.6°
2042-04-15 Tue	—	unknown	—	89.7° 12:30	7.29	24%	68.0°
2042-04-16 Wed	—	unknown	—	89.5° 12:25	7.23	14%	56.5°
2042-04-17 Thu	—	unknown	—	89.7° 12:25	7.17	7%	45.9°
2042-04-18 Fri	—	unknown	—	89.8° 12:20	7.11	2%	37.5°
2042-04-19 Sat	—	unknown	—	89.8° 12:15	7.05	0%	33.3°
2042-04-20 Sun	—	unknown	—	89.6° 12:10	7.0	1%	34.8°
2042-04-21 Mon	—	unknown	—	89.5° 12:10	6.94	5%	41.2°
2042-04-22 Tue	—	unknown	—	89.8° 12:00	6.88	11%	50.4°
2042-04-23 Wed	—	unknown	—	89.8° 12:00	6.82	19%	60.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-03-25&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.