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: 12-09 (100), 12-10 (100), 12-22 (100), 12-23 (100), 12-24 (100) — by astronomy; check the weather when the night is within four days.

2040-12-09astronomy score per night — click a bar for that night2041-01-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2040-12-21 Fri	96	—	unknown	18:35–23:50 (good, 5.25 h)	72.5° 22:05	11.51	89%	68.3°
2040-12-22 Sat	100	—	unknown	18:35–01:30 (good, 6.92 h)	72.5° 22:00	11.51	83%	80.1°
2040-12-23 Sun	100	—	unknown	18:40–02:45 (good, 8.08 h)	72.5° 22:00	11.5	75%	91.9°
2040-12-24 Mon	100	—	unknown	18:40–02:50 (good, 8.17 h)	72.5° 21:55	11.5	67%	103.8°
2040-12-25 Tue	100	—	unknown	18:40–02:55 (good, 8.25 h)	72.5° 21:50	11.5	58%	115.8°
2040-12-26 Wed	100	—	unknown	18:40–02:55 (good, 8.25 h)	72.5° 21:45	11.49	48%	128.0°
2040-12-27 Thu	100	—	unknown	18:40–02:50 (good, 8.17 h)	72.5° 21:40	11.49	38%	140.5°
2040-12-28 Fri	100	—	unknown	18:40–02:50 (good, 8.17 h)	72.5° 21:40	11.48	28%	153.3°
2040-12-29 Sat	100	—	unknown	18:40–02:45 (good, 8.08 h)	72.5° 21:35	11.47	19%	166.4°
2040-12-30 Sun	100	—	unknown	18:40–02:40 (good, 8.0 h)	72.5° 21:30	11.47	11%	176.4°
2040-12-31 Mon	100	—	unknown	18:45–02:35 (good, 7.83 h)	72.5° 21:25	11.46	5%	164.5°
2041-01-01 Tue	100	—	unknown	18:45–02:35 (good, 7.83 h)	72.5° 21:25	11.45	1%	150.0°
2041-01-02 Wed	100	—	unknown	18:45–02:30 (good, 7.75 h)	72.5° 21:20	11.44	0%	135.0°
2041-01-03 Thu	100	—	unknown	18:45–02:25 (good, 7.67 h)	72.5° 21:15	11.42	2%	120.0°
2041-01-04 Fri	100	—	unknown	18:45–02:20 (good, 7.58 h)	72.5° 21:10	11.41	7%	104.9°
2041-01-05 Sat	100	—	unknown	18:45–02:20 (good, 7.58 h)	72.5° 21:05	11.4	14%	90.0°
2041-01-06 Sun	100	—	unknown	18:50–02:15 (good, 7.42 h)	72.5° 21:05	11.38	24%	75.4°
2041-01-07 Mon	100	—	unknown	18:50–02:10 (good, 7.33 h)	72.5° 21:00	11.37	34%	61.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-09&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.