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.

Best nights for Seven Sisters: 04-11 (1), 04-12 (1) — by astronomy; check the weather when the night is within four days.

2041-04-11astronomy score per night — click a bar for that night2041-05-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-04-11 Thu	1	—	unknown	—	72.5° 15:50	7.5	81%	90.8°
2041-04-12 Fri	1	—	unknown	—	72.5° 15:45	7.44	88%	102.8°
2041-04-13 Sat	0	—	unknown	—	72.5° 15:40	7.39	94%	114.8°
2041-04-14 Sun	0	—	unknown	—	72.5° 15:40	7.33	98%	127.0°
2041-04-15 Mon	0	—	unknown	—	72.5° 15:35	7.27	100%	139.4°
2041-04-16 Tue	0	—	unknown	—	72.5° 15:30	7.21	100%	152.1°
2041-04-17 Wed	0	—	unknown	—	72.5° 15:25	7.16	98%	164.9°
2041-04-18 Thu	0	—	unknown	—	72.5° 15:20	7.1	94%	176.7°
2041-04-19 Fri	0	—	unknown	—	72.5° 15:20	7.04	88%	168.1°
2041-04-20 Sat	0	—	unknown	—	72.5° 15:15	6.98	79%	154.7°
2041-04-21 Sun	0	—	unknown	—	72.5° 15:10	6.92	70%	141.1°
2041-04-22 Mon	0	—	unknown	—	72.5° 15:05	6.87	59%	127.2°
2041-04-23 Tue	0	—	unknown	—	72.5° 15:00	6.81	48%	113.2°
2041-04-24 Wed	0	—	unknown	—	72.5° 15:00	6.75	36%	99.0°
2041-04-25 Thu	0	—	unknown	—	72.5° 14:55	6.69	26%	84.7°
2041-04-26 Fri	0	—	unknown	—	72.5° 14:50	6.63	16%	70.3°
2041-04-27 Sat	0	—	unknown	—	72.5° 14:45	6.57	8%	56.0°
2041-04-28 Sun	0	—	unknown	—	72.5° 14:45	6.52	3%	41.7°
2041-04-29 Mon	0	—	unknown	—	72.5° 14:40	6.46	0%	27.6°
2041-04-30 Tue	0	—	unknown	—	72.5° 14:35	6.4	0%	13.8°
2041-05-01 Wed	0	—	unknown	—	72.5° 14:30	6.34	2%	2.8°
2041-05-02 Thu	0	—	unknown	—	72.5° 14:25	6.28	7%	13.6°
2041-05-03 Fri	0	—	unknown	—	72.5° 14:25	6.23	13%	26.4°
2041-05-04 Sat	0	—	unknown	—	72.5° 14:20	6.17	21%	38.9°
2041-05-05 Sun	0	—	unknown	—	72.5° 14:15	6.11	29%	51.2°
2041-05-06 Mon	0	—	unknown	—	72.5° 14:10	6.05	38%	63.2°
2041-05-07 Tue	0	—	unknown	—	72.5° 14:05	6.0	48%	75.1°
2041-05-08 Wed	0	—	unknown	—	72.5° 14:05	5.94	57%	86.9°
2041-05-09 Thu	0	—	unknown	—	72.5° 14:00	5.89	66%	98.8°
2041-05-10 Fri	0	—	unknown	—	72.5° 13:55	5.83	75%	110.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-11&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.