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: 12-13 (100), 12-14 (100), 12-15 (100), 12-16 (100), 12-17 (100) — by astronomy; check the weather when the night is within four days.

2041-12-13astronomy score per night — click a bar for that night2042-01-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-12-13 Fri	100	—	unknown	18:35–01:35 (good, 7.0 h)	89.8° 19:35	11.48	65%	117.0°
2041-12-14 Sat	100	—	unknown	18:35–01:35 (good, 7.0 h)	89.7° 19:30	11.49	56%	126.0°
2041-12-15 Sun	100	—	unknown	18:35–01:30 (good, 6.92 h)	89.6° 19:25	11.49	47%	134.1°
2041-12-16 Mon	100	—	unknown	18:35–01:30 (good, 6.92 h)	89.6° 19:25	11.5	37%	140.7°
2041-12-17 Tue	100	—	unknown	18:35–01:30 (good, 6.92 h)	89.8° 19:20	11.5	28%	145.1°
2041-12-18 Wed	100	—	unknown	18:35–01:25 (good, 6.83 h)	89.8° 19:15	11.5	20%	146.0°
2041-12-19 Thu	100	—	unknown	18:35–01:20 (good, 6.75 h)	89.7° 19:10	11.51	13%	143.1°
2041-12-20 Fri	100	—	unknown	18:35–01:15 (good, 6.67 h)	89.5° 19:05	11.51	7%	136.9°
2041-12-21 Sat	100	—	unknown	18:35–01:10 (good, 6.58 h)	89.7° 19:05	11.51	2%	128.4°
2041-12-22 Sun	100	—	unknown	18:35–01:10 (good, 6.58 h)	89.8° 19:00	11.51	0%	118.3°
2041-12-23 Mon	100	—	unknown	18:40–01:05 (good, 6.42 h)	89.8° 18:55	11.51	1%	107.3°
2041-12-24 Tue	100	—	unknown	18:40–01:00 (good, 6.33 h)	89.6° 18:50	11.5	3%	95.8°
2041-12-25 Wed	100	—	unknown	18:40–00:55 (good, 6.25 h)	89.5° 18:50	11.5	9%	83.9°
2041-12-26 Thu	100	—	unknown	18:40–00:55 (good, 6.25 h)	89.7° 18:45	11.49	16%	72.2°
2041-12-27 Fri	98	—	unknown	18:40–00:50 (good, 6.17 h)	89.8° 18:40	11.49	26%	60.8°
2041-12-28 Sat	88	—	unknown	18:40–00:45 (good, 6.08 h)	89.7° 18:35	11.48	36%	50.3°
2041-12-29 Sun	80	—	unknown	18:40–00:40 (good, 6.0 h)	89.6° 18:30	11.48	48%	41.4°
2041-12-30 Mon	62	—	unknown	19:25–22:45 (good, 3.33 h)	89.6° 18:30	11.47	59%	35.4°
2041-12-31 Tue	42	—	unknown	18:45–00:55 (marginal, 6.17 h)	89.8° 18:25	11.46	70%	33.8°
2042-01-01 Wed	31	—	unknown	18:45–00:35 (marginal, 5.83 h)	89.8° 18:20	11.45	79%	37.0°
2042-01-02 Thu	28	—	unknown	18:45–00:20 (marginal, 5.58 h)	89.7° 18:15	11.44	87%	43.7°
2042-01-03 Fri	31	—	unknown	18:45–00:10 (marginal, 5.42 h)	89.5° 18:10	11.43	94%	52.6°
2042-01-04 Sat	39	—	unknown	18:45–00:10 (marginal, 5.42 h)	89.7° 18:10	11.41	98%	62.6°
2042-01-05 Sun	51	—	unknown	18:45–19:55 (good, 1.17 h)	89.8° 18:05	11.4	100%	73.0°
2042-01-06 Mon	66	—	unknown	18:50–21:35 (good, 2.75 h)	89.8° 18:00	11.39	100%	83.5°
2042-01-07 Tue	81	—	unknown	18:50–22:50 (good, 4.0 h)	89.6° 17:55	11.37	97%	94.0°
2042-01-08 Wed	100	—	unknown	18:50–23:35 (good, 4.75 h)	89.5° 17:55	11.36	93%	104.2°
2042-01-09 Thu	100	—	unknown	18:50–23:40 (good, 4.83 h)	89.7° 17:50	11.34	88%	114.0°
2042-01-10 Fri	100	—	unknown	18:50–23:45 (good, 4.92 h)	89.8° 17:45	11.32	81%	123.3°
2042-01-11 Sat	100	—	unknown	18:50–23:40 (good, 4.83 h)	89.7° 17:40	11.3	73%	131.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-12-13&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.