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: 12-22 (100), 12-23 (100), 12-24 (100), 12-25 (100), 12-26 (100) — by astronomy; check the weather when the night is within four days.

2040-12-21astronomy score per night — click a bar for that night2041-01-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2041-01-08 Tue	92	—	unknown	18:50–02:05 (good, 7.25 h)	72.5° 20:55	11.35	45%	47.3°
2041-01-09 Wed	83	—	unknown	18:50–02:00 (good, 7.17 h)	72.5° 20:50	11.34	56%	33.9°
2041-01-10 Thu	58	—	unknown	18:50–02:25 (marginal, 7.58 h)	72.5° 20:45	11.32	66%	21.0°
2041-01-11 Fri	41	—	unknown	18:55–02:10 (marginal, 7.25 h)	72.5° 20:45	11.3	75%	8.6°
2041-01-12 Sat	28	—	unknown	18:55–01:55 (marginal, 7.0 h)	72.5° 20:40	11.28	83%	5.8°
2041-01-13 Sun	21	—	unknown	22:15–01:25 (marginal, 3.17 h)	72.5° 20:35	11.26	90%	17.4°
2041-01-14 Mon	18	—	unknown	18:55–20:15 (marginal, 1.33 h)	72.5° 20:30	11.24	95%	29.4°
2041-01-15 Tue	27	—	unknown	18:55–22:55 (marginal, 4.0 h)	72.5° 20:30	11.22	98%	41.4°
2041-01-16 Wed	41	—	unknown	18:55–01:10 (marginal, 6.25 h)	72.5° 20:25	11.2	100%	53.3°
2041-01-17 Thu	59	—	unknown	19:00–20:10 (good, 1.17 h)	72.5° 20:20	11.17	100%	65.2°
2041-01-18 Fri	75	—	unknown	19:00–22:40 (good, 3.67 h)	72.5° 20:15	11.15	97%	77.0°
2041-01-19 Sat	100	—	unknown	19:00–00:00 (good, 5.0 h)	72.5° 20:10	11.12	94%	88.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-21&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.