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: 12-22 (22), 12-20 (21), 12-23 (21), 12-21 (20), 12-24 (20) — by astronomy; check the weather when the night is within four days.

2029-12-20astronomy score per night — click a bar for that night2030-01-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2029-12-20 Thu	21	—	unknown	18:35–19:20 (good, 0.75 h)	71.1° 14:25	11.51	100%	125.1°
2029-12-21 Fri	20	—	unknown	18:35–19:20 (good, 0.75 h)	71.1° 14:20	11.51	99%	132.5°
2029-12-22 Sat	22	—	unknown	18:35–19:15 (good, 0.67 h)	71.1° 14:20	11.51	96%	138.2°
2029-12-23 Sun	21	—	unknown	18:40–19:20 (good, 0.67 h)	71.1° 14:15	11.51	91%	141.3°
2029-12-24 Mon	20	—	unknown	18:40–19:15 (good, 0.58 h)	71.1° 14:10	11.5	84%	140.8°
2029-12-25 Tue	19	—	unknown	18:40–19:10 (good, 0.5 h)	71.1° 14:05	11.5	76%	136.9°
2029-12-26 Wed	17	—	unknown	18:40–19:10 (good, 0.5 h)	71.1° 14:00	11.49	66%	130.1°
2029-12-27 Thu	15	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:00	11.49	55%	121.4°
2029-12-28 Fri	14	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:55	11.48	44%	111.4°
2029-12-29 Sat	12	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:50	11.48	33%	100.6°
2029-12-30 Sun	11	—	unknown	18:40–18:50 (good, 0.17 h)	71.1° 13:45	11.47	23%	89.3°
2029-12-31 Mon	8	—	unknown	18:45–18:50 (good, 0.08 h)	71.1° 13:40	11.46	14%	78.0°
2030-01-01 Tue	7	—	unknown	18:10–19:10 (marginal, 1.0 h)	71.1° 13:40	11.45	6%	66.9°
2030-01-02 Wed	7	—	unknown	18:45–19:10 (marginal, 0.42 h)	71.1° 13:35	11.44	2%	56.5°
2030-01-03 Thu	5	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:30	11.43	0%	47.7°
2030-01-04 Fri	4	—	unknown	18:10–18:35 (marginal, 0.42 h)	71.1° 13:25	11.42	1%	41.3°
2030-01-05 Sat	3	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:25	11.4	4%	38.5°
2030-01-06 Sun	2	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:20	11.39	10%	39.8°
2030-01-07 Mon	1	—	unknown	—	71.1° 13:15	11.37	17%	44.5°
2030-01-08 Tue	1	—	unknown	—	71.1° 13:10	11.36	25%	51.3°
2030-01-09 Wed	1	—	unknown	—	71.1° 13:05	11.34	34%	59.4°
2030-01-10 Thu	0	—	unknown	—	71.1° 13:05	11.32	44%	68.1°
2030-01-11 Fri	0	—	unknown	—	71.1° 13:00	11.3	53%	77.2°
2030-01-12 Sat	0	—	unknown	—	71.1° 12:55	11.29	63%	86.4°
2030-01-13 Sun	0	—	unknown	—	71.1° 12:50	11.27	71%	95.7°
2030-01-14 Mon	0	—	unknown	—	71.1° 12:45	11.25	80%	104.9°
2030-01-15 Tue	0	—	unknown	—	71.1° 12:45	11.22	87%	113.9°
2030-01-16 Wed	0	—	unknown	—	71.1° 12:40	11.2	93%	122.5°
2030-01-17 Thu	0	—	unknown	—	71.1° 12:35	11.18	97%	130.4°
2030-01-18 Fri	0	—	unknown	—	71.1° 12:30	11.16	99%	136.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2029-12-20&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.