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: 07-16 (3), 07-15 (2), 07-10 (1), 07-11 (1), 07-12 (1) — by astronomy; check the weather when the night is within four days.

2039-06-17astronomy score per night — click a bar for that night2039-07-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-06-17 Fri	0	—	unknown	—	72.5° 11:25	4.44	12%	16.0°
2039-06-18 Sat	0	—	unknown	—	72.5° 11:20	4.43	7%	6.8°
2039-06-19 Sun	0	—	unknown	—	72.5° 11:15	4.42	3%	10.7°
2039-06-20 Mon	0	—	unknown	—	72.5° 11:10	4.42	1%	21.5°
2039-06-21 Tue	0	—	unknown	—	72.5° 11:10	4.42	0%	33.0°
2039-06-22 Wed	0	—	unknown	—	72.5° 11:05	4.42	1%	44.9°
2039-06-23 Thu	0	—	unknown	—	72.5° 11:00	4.43	4%	56.9°
2039-06-24 Fri	0	—	unknown	—	72.5° 10:55	4.43	10%	69.0°
2039-06-25 Sat	0	—	unknown	—	72.5° 10:55	4.44	16%	81.4°
2039-06-26 Sun	0	—	unknown	—	72.5° 10:50	4.45	24%	94.0°
2039-06-27 Mon	0	—	unknown	—	72.5° 10:45	4.47	34%	106.8°
2039-06-28 Tue	0	—	unknown	—	72.5° 10:40	4.48	44%	119.9°
2039-06-29 Wed	0	—	unknown	—	72.5° 10:35	4.5	55%	133.4°
2039-06-30 Thu	0	—	unknown	—	72.5° 10:35	4.51	66%	147.1°
2039-07-01 Fri	0	—	unknown	—	72.5° 10:30	4.53	77%	160.9°
2039-07-02 Sat	0	—	unknown	—	72.5° 10:25	4.56	86%	173.0°
2039-07-03 Sun	0	—	unknown	—	72.5° 10:20	4.58	93%	167.0°
2039-07-04 Mon	0	—	unknown	—	72.5° 10:15	4.61	98%	152.9°
2039-07-05 Tue	0	—	unknown	—	72.5° 10:15	4.63	100%	138.1°
2039-07-06 Wed	0	—	unknown	—	72.5° 10:10	4.66	99%	123.4°
2039-07-07 Thu	0	—	unknown	—	72.5° 10:05	4.69	95%	108.9°
2039-07-08 Fri	0	—	unknown	—	72.5° 10:00	4.73	89%	94.7°
2039-07-09 Sat	0	—	unknown	—	72.5° 10:00	4.76	81%	81.1°
2039-07-10 Sun	1	—	unknown	—	72.5° 09:55	4.79	72%	67.8°
2039-07-11 Mon	1	—	unknown	—	72.5° 09:50	4.83	62%	55.1°
2039-07-12 Tue	1	—	unknown	—	72.5° 09:45	4.87	52%	42.7°
2039-07-13 Wed	1	—	unknown	—	72.5° 09:40	4.91	42%	30.7°
2039-07-14 Thu	1	—	unknown	—	72.5° 09:40	4.95	33%	19.0°
2039-07-15 Fri	2	—	unknown	04:40–04:50 (marginal, 0.17 h)	72.5° 09:35	4.99	24%	8.7°
2039-07-16 Sat	3	—	unknown	04:30–04:50 (marginal, 0.33 h)	72.5° 09:30	5.03	17%	8.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-06-17&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.