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.

2027-05-12astronomy score per night — click a bar for that night2027-06-10

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-05-12 Wed	—	unknown	—	72.5° 13:50	5.75	47%	78.7°
2027-05-13 Thu	—	unknown	—	72.5° 13:45	5.7	58%	92.8°
2027-05-14 Fri	—	unknown	—	72.5° 13:40	5.64	69%	106.6°
2027-05-15 Sat	—	unknown	—	72.5° 13:35	5.59	79%	120.2°
2027-05-16 Sun	—	unknown	—	72.5° 13:35	5.54	87%	133.7°
2027-05-17 Mon	—	unknown	—	72.5° 13:30	5.48	93%	146.9°
2027-05-18 Tue	—	unknown	—	72.5° 13:25	5.43	97%	159.9°
2027-05-19 Wed	—	unknown	—	72.5° 13:20	5.38	100%	172.7°
2027-05-20 Thu	—	unknown	—	72.5° 13:20	5.33	100%	174.6°
2027-05-21 Fri	—	unknown	—	72.5° 13:15	5.28	98%	162.2°
2027-05-22 Sat	—	unknown	—	72.5° 13:10	5.23	94%	150.0°
2027-05-23 Sun	—	unknown	—	72.5° 13:05	5.19	89%	138.0°
2027-05-24 Mon	—	unknown	—	72.5° 13:00	5.14	82%	126.1°
2027-05-25 Tue	—	unknown	—	72.5° 13:00	5.09	74%	114.2°
2027-05-26 Wed	—	unknown	—	72.5° 12:55	5.05	66%	102.4°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-05-12&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.