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.

2027-05-27astronomy score per night — click a bar for that night2027-06-25

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-05-27 Thu	—	unknown	—	72.5° 12:50	5.0	56%	90.5°
2027-05-28 Fri	—	unknown	—	72.5° 12:45	4.96	47%	78.4°
2027-05-29 Sat	—	unknown	—	72.5° 12:40	4.92	37%	66.1°
2027-05-30 Sun	—	unknown	—	72.5° 12:40	4.88	27%	53.4°
2027-05-31 Mon	—	unknown	—	72.5° 12:35	4.84	19%	40.4°
2027-06-01 Tue	—	unknown	—	72.5° 12:30	4.8	11%	27.0°
2027-06-02 Wed	—	unknown	—	72.5° 12:25	4.77	5%	13.1°
2027-06-03 Thu	—	unknown	—	72.5° 12:25	4.73	1%	1.4°
2027-06-04 Fri	—	unknown	—	72.5° 12:20	4.7	0%	15.8°
2027-06-05 Sat	—	unknown	—	72.5° 12:15	4.67	2%	30.6°
2027-06-06 Sun	—	unknown	—	72.5° 12:10	4.64	6%	45.5°
2027-06-07 Mon	—	unknown	—	72.5° 12:05	4.61	14%	60.3°
2027-06-08 Tue	—	unknown	—	72.5° 12:00	4.59	23%	75.0°
2027-06-09 Wed	—	unknown	—	72.5° 11:55	4.56	33%	89.4°
2027-06-10 Thu	—	unknown	—	72.5° 11:50	4.54	44%	103.4°
2027-06-11 Fri	—	unknown	—	72.5° 11:45	4.52	55%	117.2°
2027-06-12 Sat	—	unknown	—	72.5° 11:45	4.5	66%	130.7°
2027-06-13 Sun	—	unknown	—	72.5° 11:40	4.48	76%	143.9°
2027-06-14 Mon	—	unknown	—	72.5° 11:35	4.47	84%	156.8°
2027-06-15 Tue	—	unknown	—	72.5° 11:30	4.45	91%	169.5°
2027-06-16 Wed	—	unknown	—	72.5° 11:30	4.44	96%	177.8°
2027-06-17 Thu	—	unknown	—	72.5° 11:25	4.44	99%	165.6°
2027-06-18 Fri	—	unknown	—	72.5° 11:20	4.43	100%	153.4°
2027-06-19 Sat	—	unknown	—	72.5° 11:15	4.42	99%	141.4°
2027-06-20 Sun	—	unknown	—	72.5° 11:10	4.42	97%	129.5°
2027-06-21 Mon	—	unknown	—	72.5° 11:10	4.42	92%	117.6°
2027-06-22 Tue	—	unknown	—	72.5° 11:05	4.42	87%	105.8°
2027-06-23 Wed	—	unknown	—	72.5° 11:00	4.43	80%	93.9°
2027-06-24 Thu	—	unknown	—	72.5° 10:55	4.43	72%	82.0°
2027-06-25 Fri	—	unknown	—	72.5° 10:50	4.44	62%	69.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-05-27&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.