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: 11-25 (100), 11-26 (100), 11-27 (100), 11-28 (100), 11-29 (100) — by astronomy; check the weather when the night is within four days.

2040-11-21astronomy score per night — click a bar for that night2040-12-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-11-21 Wed	56	—	unknown	18:35–03:20 (marginal, 8.75 h)	72.5° 00:05	11.13	90%	36.2°
2040-11-22 Thu	83	—	unknown	20:00–22:15 (good, 2.25 h)	72.5° 00:00	11.16	84%	48.2°
2040-11-23 Fri	91	—	unknown	18:50–01:45 (good, 6.92 h)	72.5° 23:55	11.18	76%	60.1°
2040-11-24 Sat	98	—	unknown	18:45–03:30 (good, 8.75 h)	72.5° 23:50	11.2	68%	71.9°
2040-11-25 Sun	100	—	unknown	18:40–04:35 (good, 9.92 h)	72.5° 23:50	11.23	59%	83.7°
2040-11-26 Mon	100	—	unknown	18:40–04:40 (good, 10.0 h)	72.5° 23:45	11.25	50%	95.6°
2040-11-27 Tue	100	—	unknown	18:35–04:45 (good, 10.17 h)	72.5° 23:40	11.27	40%	107.6°
2040-11-28 Wed	100	—	unknown	18:35–04:45 (good, 10.17 h)	72.5° 23:35	11.29	31%	119.9°
2040-11-29 Thu	100	—	unknown	18:35–04:40 (good, 10.08 h)	72.5° 23:30	11.31	22%	132.5°
2040-11-30 Fri	100	—	unknown	18:35–04:40 (good, 10.08 h)	72.5° 23:30	11.32	14%	145.4°
2040-12-01 Sat	100	—	unknown	18:35–04:35 (good, 10.0 h)	72.5° 23:25	11.34	7%	158.7°
2040-12-02 Sun	100	—	unknown	18:35–04:30 (good, 9.92 h)	72.5° 23:20	11.36	2%	172.0°
2040-12-03 Mon	100	—	unknown	18:35–04:30 (good, 9.92 h)	72.5° 23:15	11.37	0%	172.0°
2040-12-04 Tue	100	—	unknown	18:35–04:25 (good, 9.83 h)	72.5° 23:15	11.39	1%	158.1°
2040-12-05 Wed	100	—	unknown	18:35–04:20 (good, 9.75 h)	72.5° 23:10	11.4	4%	143.6°
2040-12-06 Thu	100	—	unknown	18:35–04:15 (good, 9.67 h)	72.5° 23:05	11.42	10%	128.9°
2040-12-07 Fri	100	—	unknown	18:35–04:10 (good, 9.58 h)	72.5° 23:00	11.43	18%	114.2°
2040-12-08 Sat	100	—	unknown	18:35–04:10 (good, 9.58 h)	72.5° 22:55	11.44	27%	99.7°
2040-12-09 Sun	100	—	unknown	18:35–04:05 (good, 9.5 h)	72.5° 22:55	11.45	38%	85.4°
2040-12-10 Mon	100	—	unknown	18:35–04:00 (good, 9.42 h)	72.5° 22:50	11.46	49%	71.4°
2040-12-11 Tue	98	—	unknown	19:00–03:55 (good, 8.92 h)	72.5° 22:45	11.47	60%	57.7°
2040-12-12 Wed	89	—	unknown	22:25–03:50 (good, 5.42 h)	72.5° 22:40	11.48	71%	44.3°
2040-12-13 Thu	79	—	unknown	03:20–03:50 (good, 0.5 h)	72.5° 22:35	11.48	80%	31.1°
2040-12-14 Fri	44	—	unknown	18:35–04:00 (marginal, 9.42 h)	72.5° 22:35	11.49	88%	18.2°
2040-12-15 Sat	30	—	unknown	23:35–03:40 (marginal, 4.08 h)	72.5° 22:30	11.49	94%	6.2°
2040-12-16 Sun	23	—	unknown	18:35–20:15 (marginal, 1.67 h)	72.5° 22:25	11.5	98%	8.4°
2040-12-17 Mon	24	—	unknown	18:35–20:45 (marginal, 2.17 h)	72.5° 22:20	11.5	100%	20.3°
2040-12-18 Tue	30	—	unknown	18:35–21:50 (marginal, 3.25 h)	72.5° 22:20	11.51	100%	32.5°
2040-12-19 Wed	49	—	unknown	18:35–01:30 (marginal, 6.92 h)	72.5° 22:15	11.51	98%	44.5°
2040-12-20 Thu	63	—	unknown	18:35–20:50 (good, 2.25 h)	72.5° 22:10	11.51	94%	56.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-11-21&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.