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: 12-12 (100), 12-13 (100), 12-14 (100), 12-15 (100), 12-16 (100) — by astronomy; check the weather when the night is within four days.

2041-12-04astronomy score per night — click a bar for that night2042-01-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-12-04 Wed	46	—	unknown	18:35–04:40 (marginal, 10.08 h)	72.5° 23:15	11.38	90%	23.1°
2041-12-05 Thu	30	—	unknown	00:40–04:20 (marginal, 3.67 h)	72.5° 23:10	11.4	96%	9.2°
2041-12-06 Fri	24	—	unknown	18:35–20:00 (marginal, 1.42 h)	72.5° 23:05	11.41	99%	5.3°
2041-12-07 Sat	26	—	unknown	18:35–21:15 (marginal, 2.67 h)	72.5° 23:00	11.42	100%	18.7°
2041-12-08 Sun	34	—	unknown	18:35–22:40 (marginal, 4.08 h)	72.5° 23:00	11.44	98%	32.1°
2041-12-09 Mon	54	—	unknown	18:35–03:15 (marginal, 8.67 h)	72.5° 22:55	11.45	94%	45.1°
2041-12-10 Tue	88	—	unknown	18:35–22:20 (good, 3.75 h)	72.5° 22:50	11.46	89%	57.8°
2041-12-11 Wed	97	—	unknown	18:35–01:20 (good, 6.75 h)	72.5° 22:45	11.47	82%	70.3°
2041-12-12 Thu	100	—	unknown	18:35–02:50 (good, 8.25 h)	72.5° 22:40	11.47	74%	82.5°
2041-12-13 Fri	100	—	unknown	18:35–03:30 (good, 8.92 h)	72.5° 22:40	11.48	65%	94.4°
2041-12-14 Sat	100	—	unknown	18:35–03:35 (good, 9.0 h)	72.5° 22:35	11.49	56%	106.3°
2041-12-15 Sun	100	—	unknown	18:35–03:35 (good, 9.0 h)	72.5° 22:30	11.49	47%	118.1°
2041-12-16 Mon	100	—	unknown	18:35–03:35 (good, 9.0 h)	72.5° 22:25	11.5	37%	130.0°
2041-12-17 Tue	100	—	unknown	18:35–03:30 (good, 8.92 h)	72.5° 22:25	11.5	28%	142.0°
2041-12-18 Wed	100	—	unknown	18:35–03:30 (good, 8.92 h)	72.5° 22:20	11.5	20%	154.2°
2041-12-19 Thu	100	—	unknown	18:35–03:25 (good, 8.83 h)	72.5° 22:15	11.51	13%	166.7°
2041-12-20 Fri	100	—	unknown	18:35–03:20 (good, 8.75 h)	72.5° 22:10	11.51	7%	178.0°
2041-12-21 Sat	100	—	unknown	18:35–03:20 (good, 8.75 h)	72.5° 22:05	11.51	2%	167.0°
2041-12-22 Sun	100	—	unknown	18:35–03:15 (good, 8.67 h)	72.5° 22:05	11.51	0%	153.6°
2041-12-23 Mon	100	—	unknown	18:40–03:10 (good, 8.5 h)	72.5° 22:00	11.51	1%	139.8°
2041-12-24 Tue	100	—	unknown	18:40–03:05 (good, 8.42 h)	72.5° 21:55	11.5	3%	125.7°
2041-12-25 Wed	100	—	unknown	18:40–03:00 (good, 8.33 h)	72.5° 21:50	11.5	9%	111.5°
2041-12-26 Thu	100	—	unknown	18:40–03:00 (good, 8.33 h)	72.5° 21:45	11.49	16%	97.2°
2041-12-27 Fri	100	—	unknown	18:40–02:55 (good, 8.25 h)	72.5° 21:45	11.49	26%	82.9°
2041-12-28 Sat	100	—	unknown	18:40–02:50 (good, 8.17 h)	72.5° 21:40	11.48	36%	68.6°
2041-12-29 Sun	96	—	unknown	18:40–02:45 (good, 8.08 h)	72.5° 21:35	11.48	48%	54.5°
2041-12-30 Mon	87	—	unknown	19:10–02:40 (good, 7.5 h)	72.5° 21:30	11.47	59%	40.4°
2041-12-31 Tue	61	—	unknown	02:35–02:40 (good, 0.08 h)	72.5° 21:30	11.46	70%	26.5°
2042-01-01 Wed	43	—	unknown	18:45–02:50 (marginal, 8.08 h)	72.5° 21:25	11.45	79%	12.8°
2042-01-02 Thu	28	—	unknown	18:45–02:30 (marginal, 7.75 h)	72.5° 21:20	11.44	87%	2.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-12-04&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.