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.

2028-05-16astronomy score per night — click a bar for that night2028-06-14

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-05-16 Tue	—	unknown	—	72.5° 13:30	5.5	46%	87.8°
2028-05-17 Wed	—	unknown	—	72.5° 13:25	5.45	36%	75.9°
2028-05-18 Thu	—	unknown	—	72.5° 13:25	5.39	27%	64.0°
2028-05-19 Fri	—	unknown	—	72.5° 13:20	5.34	19%	52.0°
2028-05-20 Sat	—	unknown	—	72.5° 13:15	5.29	12%	39.8°
2028-05-21 Sun	—	unknown	—	72.5° 13:10	5.24	6%	27.3°
2028-05-22 Mon	—	unknown	—	72.5° 13:05	5.2	2%	14.6°
2028-05-23 Tue	—	unknown	—	72.5° 13:05	5.15	0%	1.6°
2028-05-24 Wed	—	unknown	—	72.5° 13:00	5.1	0%	11.7°
2028-05-25 Thu	—	unknown	—	72.5° 12:55	5.06	3%	25.3°
2028-05-26 Fri	—	unknown	—	72.5° 12:50	5.01	8%	39.1°
2028-05-27 Sat	—	unknown	—	72.5° 12:45	4.97	15%	53.0°
2028-05-28 Sun	—	unknown	—	72.5° 12:45	4.93	24%	67.0°
2028-05-29 Mon	—	unknown	—	72.5° 12:40	4.89	34%	81.2°
2028-05-30 Tue	—	unknown	—	72.5° 12:35	4.85	46%	95.3°
2028-05-31 Wed	—	unknown	—	72.5° 12:30	4.81	57%	109.5°
2028-06-01 Thu	—	unknown	—	72.5° 12:30	4.78	68%	123.7°
2028-06-02 Fri	—	unknown	—	72.5° 12:25	4.74	78%	137.8°
2028-06-03 Sat	—	unknown	—	72.5° 12:20	4.71	87%	151.8°
2028-06-04 Sun	—	unknown	—	72.5° 12:15	4.68	93%	165.7°
2028-06-05 Mon	—	unknown	—	72.5° 12:10	4.65	98%	179.4°
2028-06-06 Tue	—	unknown	—	72.5° 12:10	4.62	100%	167.1°
2028-06-07 Wed	—	unknown	—	72.5° 12:00	4.59	99%	153.8°
2028-06-08 Thu	—	unknown	—	72.5° 12:00	4.57	97%	140.9°
2028-06-09 Fri	—	unknown	—	72.5° 11:50	4.54	92%	128.2°
2028-06-10 Sat	—	unknown	—	72.5° 11:50	4.52	86%	115.8°
2028-06-11 Sun	—	unknown	—	72.5° 11:45	4.5	79%	103.7°
2028-06-12 Mon	—	unknown	—	72.5° 11:40	4.49	71%	91.7°
2028-06-13 Tue	—	unknown	—	72.5° 11:35	4.47	62%	79.8°
2028-06-14 Wed	—	unknown	—	72.5° 11:35	4.46	52%	68.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-05-16&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.