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 HD 189733: 02-04 (3), 02-03 (2), 01-06 (1), 01-07 (1), 01-08 (1) — by astronomy; check the weather when the night is within four days.

2041-01-06astronomy score per night — click a bar for that night2041-02-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-01-06 Sun	1	—	unknown	—	71.1° 13:20	11.38	24%	57.2°
2041-01-07 Mon	1	—	unknown	—	71.1° 13:15	11.37	34%	65.0°
2041-01-08 Tue	1	—	unknown	—	71.1° 13:10	11.35	45%	73.6°
2041-01-09 Wed	1	—	unknown	—	71.1° 13:05	11.34	56%	82.4°
2041-01-10 Thu	0	—	unknown	—	71.1° 13:00	11.32	66%	91.3°
2041-01-11 Fri	0	—	unknown	—	71.1° 13:00	11.3	75%	100.0°
2041-01-12 Sat	0	—	unknown	—	71.1° 12:55	11.28	83%	108.2°
2041-01-13 Sun	0	—	unknown	—	71.1° 12:50	11.26	90%	115.7°
2041-01-14 Mon	0	—	unknown	—	71.1° 12:45	11.24	95%	122.4°
2041-01-15 Tue	0	—	unknown	—	71.1° 12:40	11.22	98%	127.7°
2041-01-16 Wed	0	—	unknown	—	71.1° 12:40	11.2	100%	131.3°
2041-01-17 Thu	0	—	unknown	—	71.1° 12:35	11.17	100%	132.9°
2041-01-18 Fri	0	—	unknown	—	71.1° 12:30	11.15	97%	132.2°
2041-01-19 Sat	0	—	unknown	—	71.1° 12:25	11.12	94%	129.4°
2041-01-20 Sun	0	—	unknown	—	71.1° 12:25	11.1	88%	124.8°
2041-01-21 Mon	0	—	unknown	—	71.1° 12:20	11.07	82%	118.8°
2041-01-22 Tue	0	—	unknown	—	71.1° 12:15	11.05	74%	111.7°
2041-01-23 Wed	0	—	unknown	—	71.1° 12:10	11.02	65%	103.9°
2041-01-24 Thu	0	—	unknown	—	71.1° 12:05	10.99	55%	95.6°
2041-01-25 Fri	0	—	unknown	—	71.1° 12:00	10.96	45%	86.9°
2041-01-26 Sat	0	—	unknown	—	71.1° 11:55	10.93	34%	78.0°
2041-01-27 Sun	0	—	unknown	—	71.1° 11:50	10.9	24%	69.2°
2041-01-28 Mon	1	—	unknown	—	71.1° 11:45	10.87	15%	60.8°
2041-01-29 Tue	1	—	unknown	—	71.1° 11:45	10.84	8%	53.7°
2041-01-30 Wed	1	—	unknown	—	71.1° 11:40	10.81	3%	48.8°
2041-01-31 Thu	1	—	unknown	—	71.1° 11:35	10.78	0%	47.1°
2041-02-01 Fri	1	—	unknown	—	71.1° 11:30	10.75	1%	49.1°
2041-02-02 Sat	1	—	unknown	06:25–06:30 (marginal, 0.08 h)	71.1° 11:30	10.71	5%	54.3°
2041-02-03 Sun	2	—	unknown	06:25–06:30 (marginal, 0.08 h)	71.1° 11:25	10.68	11%	61.7°
2041-02-04 Mon	3	—	unknown	06:20–06:30 (marginal, 0.17 h)	71.1° 11:20	10.64	19%	70.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-01-06&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.