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 Andromeda Galaxy: 01-10 (100), 01-11 (100), 01-12 (100), 01-13 (100), 01-14 (100) — by astronomy; check the weather when the night is within four days.

2031-01-10astronomy score per night — click a bar for that night2031-02-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-01-10 Fri	100	—	unknown	18:50–23:30 (good, 4.67 h)	89.7° 17:45	11.33	96%	106.5°
2031-01-11 Sat	100	—	unknown	18:50–23:35 (good, 4.75 h)	89.6° 17:40	11.31	91%	116.8°
2031-01-12 Sun	100	—	unknown	18:55–23:35 (good, 4.67 h)	89.5° 17:40	11.29	84%	126.9°
2031-01-13 Mon	100	—	unknown	18:55–23:35 (good, 4.67 h)	89.7° 17:35	11.27	76%	136.2°
2031-01-14 Tue	100	—	unknown	18:55–23:35 (good, 4.67 h)	89.7° 17:30	11.25	67%	144.1°
2031-01-15 Wed	100	—	unknown	18:55–23:35 (good, 4.67 h)	89.7° 17:25	11.23	56%	149.1°
2031-01-16 Thu	100	—	unknown	18:55–23:30 (good, 4.58 h)	89.5° 17:20	11.21	46%	149.3°
2031-01-17 Fri	100	—	unknown	19:00–23:25 (good, 4.42 h)	89.6° 17:20	11.19	35%	144.4°
2031-01-18 Sat	100	—	unknown	19:00–23:25 (good, 4.42 h)	89.7° 17:15	11.16	24%	135.6°
2031-01-19 Sun	100	—	unknown	19:00–23:20 (good, 4.33 h)	89.7° 17:10	11.14	15%	124.6°
2031-01-20 Mon	100	—	unknown	19:00–23:15 (good, 4.25 h)	89.6° 17:05	11.11	7%	112.4°
2031-01-21 Tue	100	—	unknown	19:00–23:10 (good, 4.17 h)	89.5° 17:00	11.09	2%	99.6°
2031-01-22 Wed	100	—	unknown	19:05–23:05 (good, 4.0 h)	89.6° 17:00	11.06	0%	86.6°
2031-01-23 Thu	100	—	unknown	19:05–23:05 (good, 4.0 h)	89.7° 16:55	11.03	1%	73.8°
2031-01-24 Fri	100	—	unknown	19:05–23:00 (good, 3.92 h)	89.7° 16:50	11.01	4%	61.6°
2031-01-25 Sat	95	—	unknown	19:05–22:55 (good, 3.83 h)	89.6° 16:45	10.98	10%	50.3°
2031-01-26 Sun	84	—	unknown	19:05–22:50 (good, 3.75 h)	89.5° 16:45	10.95	18%	40.6°
2031-01-27 Mon	69	—	unknown	19:10–22:35 (good, 3.42 h)	89.7° 16:40	10.92	27%	33.5°
2031-01-28 Tue	55	—	unknown	19:10–22:20 (good, 3.17 h)	89.7° 16:35	10.89	36%	30.3°
2031-01-29 Wed	43	—	unknown	19:10–21:25 (good, 2.25 h)	89.7° 16:30	10.86	46%	31.7°
2031-01-30 Thu	34	—	unknown	19:10–23:05 (marginal, 3.92 h)	89.6° 16:25	10.83	56%	36.9°
2031-01-31 Fri	28	—	unknown	19:15–22:50 (marginal, 3.58 h)	89.6° 16:25	10.8	65%	44.4°
2031-02-01 Sat	25	—	unknown	19:15–22:40 (marginal, 3.42 h)	89.7° 16:20	10.76	74%	53.2°
2031-02-02 Sun	25	—	unknown	19:15–22:35 (marginal, 3.33 h)	89.7° 16:15	10.73	82%	62.7°
2031-02-03 Mon	28	—	unknown	19:15–22:35 (marginal, 3.33 h)	89.7° 16:10	10.7	88%	72.6°
2031-02-04 Tue	33	—	unknown	19:15–19:55 (good, 0.67 h)	89.5° 16:05	10.66	94%	82.8°
2031-02-05 Wed	38	—	unknown	19:20–20:50 (good, 1.5 h)	89.6° 16:05	10.63	97%	93.2°
2031-02-06 Thu	45	—	unknown	19:20–21:40 (good, 2.33 h)	89.7° 16:00	10.59	100%	103.7°
2031-02-07 Fri	51	—	unknown	19:20–21:45 (good, 2.42 h)	89.7° 15:55	10.56	100%	114.2°
2031-02-08 Sat	56	—	unknown	19:20–21:50 (good, 2.5 h)	89.6° 15:50	10.52	98%	124.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-01-10&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.