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.

2042-04-27astronomy score per night — click a bar for that night2042-05-26

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-04-27 Sun	—	unknown	—	72.5° 14:50	6.59	58%	77.2°
2042-04-28 Mon	—	unknown	—	72.5° 14:45	6.53	68%	89.3°
2042-04-29 Tue	—	unknown	—	72.5° 14:40	6.47	76%	101.2°
2042-04-30 Wed	—	unknown	—	72.5° 14:35	6.41	84%	113.0°
2042-05-01 Thu	—	unknown	—	72.5° 14:30	6.36	90%	124.8°
2042-05-02 Fri	—	unknown	—	72.5° 14:30	6.3	95%	136.7°
2042-05-03 Sat	—	unknown	—	72.5° 14:25	6.24	98%	148.6°
2042-05-04 Sun	—	unknown	—	72.5° 14:20	6.18	100%	160.7°
2042-05-05 Mon	—	unknown	—	72.5° 14:15	6.13	100%	172.8°
2042-05-06 Tue	—	unknown	—	72.5° 14:10	6.07	97%	174.6°
2042-05-07 Wed	—	unknown	—	72.5° 14:10	6.01	93%	162.2°
2042-05-08 Thu	—	unknown	—	72.5° 14:05	5.96	87%	149.4°
2042-05-09 Fri	—	unknown	—	72.5° 14:00	5.9	79%	136.5°
2042-05-10 Sat	—	unknown	—	72.5° 13:55	5.84	70%	123.3°
2042-05-11 Sun	—	unknown	—	72.5° 13:55	5.79	60%	109.9°
2042-05-12 Mon	—	unknown	—	72.5° 13:50	5.73	49%	96.2°
2042-05-13 Tue	—	unknown	—	72.5° 13:45	5.68	37%	82.1°
2042-05-14 Wed	—	unknown	—	72.5° 13:40	5.62	27%	67.8°
2042-05-15 Thu	—	unknown	—	72.5° 13:35	5.57	17%	53.3°
2042-05-16 Fri	—	unknown	—	72.5° 13:35	5.52	9%	38.5°
2042-05-17 Sat	—	unknown	—	72.5° 13:30	5.47	3%	23.7°
2042-05-18 Sun	—	unknown	—	72.5° 13:25	5.41	0%	9.0°
2042-05-19 Mon	—	unknown	—	72.5° 13:20	5.36	0%	5.8°
2042-05-20 Tue	—	unknown	—	72.5° 13:15	5.31	3%	20.0°
2042-05-21 Wed	—	unknown	—	72.5° 13:15	5.26	8%	33.8°
2042-05-22 Thu	—	unknown	—	72.5° 13:10	5.22	15%	47.3°
2042-05-23 Fri	—	unknown	—	72.5° 13:05	5.17	23%	60.4°
2042-05-24 Sat	—	unknown	—	72.5° 13:00	5.12	32%	73.1°
2042-05-25 Sun	—	unknown	—	72.5° 12:55	5.08	42%	85.4°
2042-05-26 Mon	—	unknown	—	72.5° 12:55	5.03	52%	97.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-04-27&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.