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: 01-02 (6), 01-03 (5), 01-04 (4), 01-05 (3), 01-06 (1) — by astronomy; check the weather when the night is within four days.

2041-01-02astronomy score per night — click a bar for that night2041-01-31

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-01-02 Wed	6	—	unknown	18:10–18:40 (marginal, 0.5 h)	71.1° 13:35	11.44	0%	51.0°
2041-01-03 Thu	5	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:30	11.42	2%	47.5°
2041-01-04 Fri	4	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	7%	47.6°
2041-01-05 Sat	3	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:20	11.4	14%	51.1°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-01-02&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.