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.

2039-05-22astronomy score per night — click a bar for that night2039-06-20

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-05-22 Sun	—	unknown	—	72.5° 13:10	5.23	0%	6.1°
2039-05-23 Mon	—	unknown	—	72.5° 13:05	5.18	1%	13.2°
2039-05-24 Tue	—	unknown	—	72.5° 13:00	5.13	3%	24.3°
2039-05-25 Wed	—	unknown	—	72.5° 13:00	5.09	7%	35.9°
2039-05-26 Thu	—	unknown	—	72.5° 12:55	5.04	13%	47.7°
2039-05-27 Fri	—	unknown	—	72.5° 12:50	5.0	20%	59.7°
2039-05-28 Sat	—	unknown	—	72.5° 12:45	4.96	28%	71.9°
2039-05-29 Sun	—	unknown	—	72.5° 12:45	4.92	38%	84.4°
2039-05-30 Mon	—	unknown	—	72.5° 12:40	4.88	48%	97.1°
2039-05-31 Tue	—	unknown	—	72.5° 12:35	4.84	59%	110.3°
2039-06-01 Wed	—	unknown	—	72.5° 12:30	4.8	69%	123.8°
2039-06-02 Thu	—	unknown	—	72.5° 12:25	4.77	79%	137.8°
2039-06-03 Fri	—	unknown	—	72.5° 12:25	4.73	88%	152.0°
2039-06-04 Sat	—	unknown	—	72.5° 12:20	4.7	95%	166.2°
2039-06-05 Sun	—	unknown	—	72.5° 12:15	4.67	99%	173.3°
2039-06-06 Mon	—	unknown	—	72.5° 12:10	4.64	100%	161.1°
2039-06-07 Tue	—	unknown	—	72.5° 12:05	4.61	98%	146.4°
2039-06-08 Wed	—	unknown	—	72.5° 12:00	4.58	93%	131.6°
2039-06-09 Thu	—	unknown	—	72.5° 11:55	4.56	86%	117.2°
2039-06-10 Fri	—	unknown	—	72.5° 11:50	4.54	77%	103.1°
2039-06-11 Sat	—	unknown	—	72.5° 11:50	4.52	67%	89.5°
2039-06-12 Sun	—	unknown	—	72.5° 11:45	4.5	57%	76.4°
2039-06-13 Mon	—	unknown	—	72.5° 11:40	4.48	47%	63.7°
2039-06-14 Tue	—	unknown	—	72.5° 11:35	4.47	37%	51.3°
2039-06-15 Wed	—	unknown	—	72.5° 11:30	4.45	28%	39.2°
2039-06-16 Thu	—	unknown	—	72.5° 11:30	4.44	19%	27.4°
2039-06-17 Fri	—	unknown	—	72.5° 11:25	4.44	12%	16.0°
2039-06-18 Sat	—	unknown	—	72.5° 11:20	4.43	7%	6.8°
2039-06-19 Sun	—	unknown	—	72.5° 11:15	4.42	3%	10.7°
2039-06-20 Mon	—	unknown	—	72.5° 11:10	4.42	1%	21.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-05-22&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.