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: 09-18 (100), 09-19 (100), 09-20 (100), 09-21 (100), 09-22 (100) — by astronomy; check the weather when the night is within four days.

2047-09-18astronomy score per night — click a bar for that night2047-10-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-09-18 Wed	100	—	unknown	00:15–05:35 (good, 5.33 h)	72.6° 05:20	8.52	1%	104.9°
2047-09-19 Thu	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.6° 05:15	8.58	0%	119.5°
2047-09-20 Fri	100	—	unknown	00:05–05:35 (good, 5.5 h)	72.6° 05:10	8.63	2%	134.3°
2047-09-21 Sat	100	—	unknown	00:00–05:35 (good, 5.58 h)	72.6° 05:05	8.68	7%	149.1°
2047-09-22 Sun	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.6° 05:05	8.73	14%	163.9°
2047-09-23 Mon	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.6° 05:00	8.78	23%	178.4°
2047-09-24 Tue	100	—	unknown	23:50–05:40 (good, 5.83 h)	72.6° 04:55	8.83	34%	167.0°
2047-09-25 Wed	100	—	unknown	23:45–05:40 (good, 5.92 h)	72.6° 04:50	8.88	45%	152.9°
2047-09-26 Thu	100	—	unknown	23:45–05:45 (good, 6.0 h)	72.6° 04:45	8.93	56%	139.1°
2047-09-27 Fri	100	—	unknown	23:45–05:45 (good, 6.0 h)	72.6° 04:45	8.98	66%	125.6°
2047-09-28 Sat	100	—	unknown	23:45–05:45 (good, 6.0 h)	72.6° 04:40	9.03	76%	112.4°
2047-09-29 Sun	100	—	unknown	23:50–05:45 (good, 5.92 h)	72.6° 04:35	9.08	84%	99.5°
2047-09-30 Mon	100	—	unknown	00:25–05:50 (good, 5.42 h)	72.6° 04:30	9.13	91%	86.8°
2047-10-01 Tue	100	—	unknown	01:55–05:50 (good, 3.92 h)	72.6° 04:25	9.18	96%	74.2°
2047-10-02 Wed	63	—	unknown	04:25–05:50 (good, 1.42 h)	72.6° 04:25	9.22	99%	61.9°
2047-10-03 Thu	42	—	unknown	23:30–05:50 (marginal, 6.33 h)	72.6° 04:20	9.27	100%	49.7°
2047-10-04 Fri	26	—	unknown	02:00–05:50 (marginal, 3.83 h)	72.6° 04:15	9.32	99%	37.6°
2047-10-05 Sat	19	—	unknown	04:30–05:55 (marginal, 1.42 h)	72.6° 04:10	9.37	96%	25.7°
2047-10-06 Sun	20	—	unknown	23:20–01:05 (marginal, 1.75 h)	72.6° 04:10	9.41	92%	13.8°
2047-10-07 Mon	25	—	unknown	23:00–05:55 (marginal, 6.92 h)	72.6° 04:05	9.46	86%	2.2°
2047-10-08 Tue	36	—	unknown	22:40–05:55 (marginal, 7.25 h)	72.6° 04:00	9.5	79%	9.9°
2047-10-09 Wed	50	—	unknown	22:30–06:00 (marginal, 7.5 h)	72.6° 03:55	9.55	71%	21.7°
2047-10-10 Thu	63	—	unknown	23:30–02:50 (good, 3.33 h)	72.6° 03:50	9.6	62%	33.8°
2047-10-11 Fri	84	—	unknown	22:40–06:00 (good, 7.33 h)	72.6° 03:50	9.64	53%	46.0°
2047-10-12 Sat	93	—	unknown	22:40–06:00 (good, 7.33 h)	72.6° 03:45	9.69	43%	58.5°
2047-10-13 Sun	100	—	unknown	22:35–06:00 (good, 7.42 h)	72.6° 03:40	9.73	33%	71.4°
2047-10-14 Mon	100	—	unknown	22:30–06:05 (good, 7.58 h)	72.6° 03:35	9.77	23%	84.8°
2047-10-15 Tue	100	—	unknown	22:25–06:05 (good, 7.67 h)	72.6° 03:30	9.82	14%	98.6°
2047-10-16 Wed	100	—	unknown	22:25–06:05 (good, 7.67 h)	72.6° 03:30	9.86	7%	112.9°
2047-10-17 Thu	100	—	unknown	22:20–06:05 (good, 7.75 h)	72.6° 03:25	9.9	2%	127.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-09-18&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.