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: 12-20 (100), 12-21 (100), 12-22 (100), 12-23 (100), 12-24 (100) — by astronomy; check the weather when the night is within four days.

2038-12-20astronomy score per night — click a bar for that night2039-01-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-12-20 Mon	100	—	unknown	18:35–01:15 (good, 6.67 h)	89.6° 19:10	11.51	33%	140.7°
2038-12-21 Tue	100	—	unknown	18:35–01:15 (good, 6.67 h)	89.8° 19:05	11.51	23%	141.8°
2038-12-22 Wed	100	—	unknown	18:35–01:10 (good, 6.58 h)	89.8° 19:00	11.51	14%	138.4°
2038-12-23 Thu	100	—	unknown	18:40–01:05 (good, 6.42 h)	89.6° 18:55	11.51	6%	131.2°
2038-12-24 Fri	100	—	unknown	18:40–01:00 (good, 6.33 h)	89.5° 18:55	11.5	2%	121.7°
2038-12-25 Sat	100	—	unknown	18:40–01:00 (good, 6.33 h)	89.7° 18:50	11.5	0%	110.9°
2038-12-26 Sun	100	—	unknown	18:40–00:55 (good, 6.25 h)	89.8° 18:45	11.5	1%	99.6°
2038-12-27 Mon	100	—	unknown	18:40–00:50 (good, 6.17 h)	89.7° 18:40	11.49	5%	88.4°
2038-12-28 Tue	100	—	unknown	18:40–00:45 (good, 6.08 h)	89.6° 18:35	11.48	11%	77.5°
2038-12-29 Wed	100	—	unknown	18:40–00:40 (good, 6.0 h)	89.6° 18:35	11.48	18%	67.2°
2038-12-30 Thu	95	—	unknown	18:40–00:40 (good, 6.0 h)	89.7° 18:30	11.47	27%	57.9°
2038-12-31 Fri	87	—	unknown	18:45–00:35 (good, 5.83 h)	89.8° 18:25	11.46	37%	49.7°
2039-01-01 Sat	77	—	unknown	18:45–00:30 (good, 5.75 h)	89.7° 18:20	11.45	46%	43.3°
2039-01-02 Sun	66	—	unknown	18:45–23:55 (good, 5.17 h)	89.5° 18:15	11.44	56%	39.2°
2039-01-03 Mon	50	—	unknown	18:45–00:50 (marginal, 6.08 h)	89.6° 18:15	11.43	65%	38.0°
2039-01-04 Tue	39	—	unknown	18:45–00:35 (marginal, 5.83 h)	89.8° 18:10	11.42	74%	39.9°
2039-01-05 Wed	33	—	unknown	18:45–00:20 (marginal, 5.58 h)	89.8° 18:05	11.4	82%	44.5°
2039-01-06 Thu	32	—	unknown	18:50–00:10 (marginal, 5.33 h)	89.6° 18:00	11.39	88%	51.0°
2039-01-07 Fri	35	—	unknown	18:50–00:00 (marginal, 5.17 h)	89.5° 18:00	11.38	94%	58.9°
2039-01-08 Sat	43	—	unknown	18:50–00:00 (marginal, 5.17 h)	89.7° 17:55	11.36	98%	67.7°
2039-01-09 Sun	53	—	unknown	18:50–20:40 (good, 1.83 h)	89.8° 17:50	11.34	100%	77.1°
2039-01-10 Mon	67	—	unknown	18:50–21:45 (good, 2.92 h)	89.7° 17:45	11.33	100%	87.0°
2039-01-11 Tue	82	—	unknown	18:50–22:55 (good, 4.08 h)	89.6° 17:40	11.31	98%	97.1°
2039-01-12 Wed	100	—	unknown	18:55–23:25 (good, 4.5 h)	89.6° 17:40	11.29	94%	107.2°
2039-01-13 Thu	100	—	unknown	18:55–23:30 (good, 4.58 h)	89.7° 17:35	11.27	88%	117.1°
2039-01-14 Fri	100	—	unknown	18:55–23:30 (good, 4.58 h)	89.8° 17:30	11.25	80%	126.3°
2039-01-15 Sat	100	—	unknown	18:55–23:30 (good, 4.58 h)	89.7° 17:25	11.23	70%	134.2°
2039-01-16 Sun	100	—	unknown	18:55–23:30 (good, 4.58 h)	89.5° 17:20	11.21	59%	139.9°
2039-01-17 Mon	100	—	unknown	19:00–23:25 (good, 4.42 h)	89.6° 17:20	11.18	48%	142.0°
2039-01-18 Tue	100	—	unknown	19:00–23:25 (good, 4.42 h)	89.8° 17:15	11.16	37%	139.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-12-20&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.