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: 07-15 (3), 07-14 (2), 07-10 (1), 07-11 (1), 07-12 (1) — by astronomy; check the weather when the night is within four days.

2031-06-16astronomy score per night — click a bar for that night2031-07-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-06-16 Mon	0	—	unknown	—	72.5° 11:30	4.44	8%	8.1°
2031-06-17 Tue	0	—	unknown	—	72.5° 11:25	4.44	4%	6.7°
2031-06-18 Wed	0	—	unknown	—	72.5° 11:20	4.43	1%	17.8°
2031-06-19 Thu	0	—	unknown	—	72.5° 11:15	4.43	0%	29.4°
2031-06-20 Fri	0	—	unknown	—	72.5° 11:10	4.42	1%	41.2°
2031-06-21 Sat	0	—	unknown	—	72.5° 11:10	4.42	4%	52.9°
2031-06-22 Sun	0	—	unknown	—	72.5° 11:05	4.42	8%	64.7°
2031-06-23 Mon	0	—	unknown	—	72.5° 11:00	4.43	14%	76.6°
2031-06-24 Tue	0	—	unknown	—	72.5° 10:55	4.43	21%	88.5°
2031-06-25 Wed	0	—	unknown	—	72.5° 10:50	4.44	30%	100.6°
2031-06-26 Thu	0	—	unknown	—	72.5° 10:50	4.45	39%	112.9°
2031-06-27 Fri	0	—	unknown	—	72.5° 10:45	4.46	49%	125.5°
2031-06-28 Sat	0	—	unknown	—	72.5° 10:40	4.48	60%	138.5°
2031-06-29 Sun	0	—	unknown	—	72.5° 10:35	4.5	70%	151.8°
2031-06-30 Mon	0	—	unknown	—	72.5° 10:35	4.51	80%	165.4°
2031-07-01 Tue	0	—	unknown	—	72.5° 10:30	4.53	88%	175.7°
2031-07-02 Wed	0	—	unknown	—	72.5° 10:25	4.56	95%	164.2°
2031-07-03 Thu	0	—	unknown	—	72.5° 10:20	4.58	99%	149.5°
2031-07-04 Fri	0	—	unknown	—	72.5° 10:15	4.6	100%	134.3°
2031-07-05 Sat	0	—	unknown	—	72.5° 10:15	4.63	98%	119.1°
2031-07-06 Sun	0	—	unknown	—	72.5° 10:10	4.66	93%	104.1°
2031-07-07 Mon	0	—	unknown	—	72.5° 10:05	4.69	86%	89.4°
2031-07-08 Tue	0	—	unknown	—	72.5° 10:00	4.72	77%	75.1°
2031-07-09 Wed	0	—	unknown	—	72.5° 09:55	4.76	66%	61.3°
2031-07-10 Thu	1	—	unknown	—	72.5° 09:55	4.79	56%	47.9°
2031-07-11 Fri	1	—	unknown	—	72.5° 09:50	4.83	45%	35.0°
2031-07-12 Sat	1	—	unknown	—	72.5° 09:45	4.87	36%	22.5°
2031-07-13 Sun	1	—	unknown	—	72.5° 09:40	4.91	26%	10.7°
2031-07-14 Mon	2	—	unknown	04:40–04:45 (marginal, 0.08 h)	72.5° 09:40	4.95	18%	5.0°
2031-07-15 Tue	3	—	unknown	04:35–04:50 (marginal, 0.25 h)	72.5° 09:35	4.99	12%	15.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-06-16&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.