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: 12-18 (100), 12-19 (100), 12-20 (100), 12-21 (100), 12-22 (100) — by astronomy; check the weather when the night is within four days.

2030-12-18astronomy score per night — click a bar for that night2031-01-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-12-18 Wed	100	—	unknown	18:35–01:25 (good, 6.83 h)	89.7° 19:15	11.5	40%	145.9°
2030-12-19 Thu	100	—	unknown	18:35–01:20 (good, 6.75 h)	89.5° 19:10	11.51	30%	149.9°
2030-12-20 Fri	100	—	unknown	18:35–01:15 (good, 6.67 h)	89.6° 19:10	11.51	20%	148.4°
2030-12-21 Sat	100	—	unknown	18:35–01:15 (good, 6.67 h)	89.7° 19:05	11.51	11%	141.6°
2030-12-22 Sun	100	—	unknown	18:35–01:10 (good, 6.58 h)	89.7° 19:00	11.51	5%	131.4°
2030-12-23 Mon	100	—	unknown	18:40–01:05 (good, 6.42 h)	89.6° 18:55	11.51	1%	119.5°
2030-12-24 Tue	100	—	unknown	18:40–01:00 (good, 6.33 h)	89.5° 18:50	11.5	0%	106.7°
2030-12-25 Wed	100	—	unknown	18:40–00:55 (good, 6.25 h)	89.6° 18:50	11.5	2%	93.6°
2030-12-26 Thu	100	—	unknown	18:40–00:55 (good, 6.25 h)	89.7° 18:45	11.5	7%	80.6°
2030-12-27 Fri	100	—	unknown	18:40–00:50 (good, 6.17 h)	89.7° 18:40	11.49	14%	68.2°
2030-12-28 Sat	97	—	unknown	18:40–00:45 (good, 6.08 h)	89.6° 18:35	11.48	23%	56.5°
2030-12-29 Sun	89	—	unknown	18:40–00:40 (good, 6.0 h)	89.5° 18:35	11.48	33%	46.1°
2030-12-30 Mon	81	—	unknown	18:40–00:40 (good, 6.0 h)	89.7° 18:30	11.47	44%	37.5°
2030-12-31 Tue	65	—	unknown	18:45–00:00 (good, 5.25 h)	89.7° 18:25	11.46	54%	31.7°
2031-01-01 Wed	47	—	unknown	18:45–01:00 (marginal, 6.25 h)	89.7° 18:20	11.45	64%	30.0°
2031-01-02 Thu	35	—	unknown	18:45–00:40 (marginal, 5.92 h)	89.5° 18:15	11.44	72%	32.7°
2031-01-03 Fri	30	—	unknown	18:45–00:25 (marginal, 5.67 h)	89.6° 18:15	11.43	81%	38.6°
2031-01-04 Sat	30	—	unknown	18:45–00:15 (marginal, 5.5 h)	89.7° 18:10	11.42	88%	46.6°
2031-01-05 Sun	34	—	unknown	18:45–00:05 (marginal, 5.33 h)	89.7° 18:05	11.4	93%	55.6°
2031-01-06 Mon	42	—	unknown	18:50–00:10 (marginal, 5.33 h)	89.6° 18:00	11.39	97%	65.3°
2031-01-07 Tue	53	—	unknown	18:50–20:30 (good, 1.67 h)	89.5° 17:55	11.38	99%	75.4°
2031-01-08 Wed	67	—	unknown	18:50–21:45 (good, 2.92 h)	89.6° 17:55	11.36	100%	85.7°
2031-01-09 Thu	82	—	unknown	18:50–22:50 (good, 4.0 h)	89.7° 17:50	11.34	99%	96.1°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-12-18&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.