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: 12-26 (17), 12-24 (16), 12-25 (16), 12-27 (16), 12-28 (14) — by astronomy; check the weather when the night is within four days.

2045-12-24astronomy score per night — click a bar for that night2046-01-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-12-24 Sun	16	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:10	11.5	99%	130.6°
2045-12-25 Mon	16	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:05	11.5	95%	135.8°
2045-12-26 Tue	17	—	unknown	18:40–19:10 (good, 0.5 h)	71.1° 14:00	11.49	89%	137.5°
2045-12-27 Wed	16	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:00	11.49	80%	135.2°
2045-12-28 Thu	14	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:55	11.48	70%	129.6°
2045-12-29 Fri	12	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:50	11.48	59%	121.8°
2045-12-30 Sat	11	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:45	11.47	48%	112.7°
2045-12-31 Sun	8	—	unknown	18:45–18:50 (good, 0.08 h)	71.1° 13:45	11.46	37%	103.0°
2046-01-01 Mon	7	—	unknown	18:10–19:10 (marginal, 1.0 h)	71.1° 13:40	11.45	27%	93.1°
2046-01-02 Tue	7	—	unknown	18:45–19:10 (marginal, 0.42 h)	71.1° 13:35	11.44	18%	83.3°
2046-01-03 Wed	6	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:30	11.43	11%	73.8°
2046-01-04 Thu	4	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	5%	64.9°
2046-01-05 Fri	3	—	unknown	18:15–18:30 (marginal, 0.25 h)	71.1° 13:25	11.4	2%	56.8°
2046-01-06 Sat	3	—	unknown	18:15–18:25 (marginal, 0.17 h)	71.1° 13:20	11.39	0%	50.1°
2046-01-07 Sun	2	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:15	11.37	1%	45.2°
2046-01-08 Mon	1	—	unknown	—	71.1° 13:10	11.36	3%	42.7°
2046-01-09 Tue	1	—	unknown	—	71.1° 13:05	11.34	7%	42.8°
2046-01-10 Wed	1	—	unknown	—	71.1° 13:05	11.32	12%	45.6°
2046-01-11 Thu	1	—	unknown	—	71.1° 13:00	11.3	19%	50.5°
2046-01-12 Fri	0	—	unknown	—	71.1° 12:55	11.28	27%	56.9°
2046-01-13 Sat	0	—	unknown	—	71.1° 12:50	11.26	36%	64.4°
2046-01-14 Sun	0	—	unknown	—	71.1° 12:45	11.24	45%	72.7°
2046-01-15 Mon	0	—	unknown	—	71.1° 12:45	11.22	55%	81.5°
2046-01-16 Tue	0	—	unknown	—	71.1° 12:40	11.2	65%	90.7°
2046-01-17 Wed	0	—	unknown	—	71.1° 12:35	11.18	75%	100.2°
2046-01-18 Thu	0	—	unknown	—	71.1° 12:30	11.15	83%	109.8°
2046-01-19 Fri	0	—	unknown	—	71.1° 12:30	11.13	91%	119.1°
2046-01-20 Sat	0	—	unknown	—	71.1° 12:25	11.1	96%	127.5°
2046-01-21 Sun	0	—	unknown	—	71.1° 12:20	11.08	100%	134.0°
2046-01-22 Mon	0	—	unknown	—	71.1° 12:15	11.05	100%	137.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-12-24&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.