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: 05-10 (3), 05-08 (2), 05-09 (2), 04-26 (1), 04-27 (1) — by astronomy; check the weather when the night is within four days.

2037-04-11astronomy score per night — click a bar for that night2037-05-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-04-11 Sat	0	—	unknown	—	89.7° 12:45	7.5	12%	57.2°
2037-04-12 Sun	0	—	unknown	—	89.6° 12:40	7.45	7%	49.7°
2037-04-13 Mon	0	—	unknown	—	89.6° 12:40	7.39	3%	43.6°
2037-04-14 Tue	0	—	unknown	—	89.7° 12:35	7.33	1%	39.5°
2037-04-15 Wed	0	—	unknown	—	89.8° 12:30	7.27	0%	38.4°
2037-04-16 Thu	0	—	unknown	—	89.7° 12:25	7.22	2%	40.5°
2037-04-17 Fri	0	—	unknown	—	89.5° 12:20	7.16	5%	45.5°
2037-04-18 Sat	0	—	unknown	—	89.6° 12:20	7.1	11%	52.8°
2037-04-19 Sun	0	—	unknown	—	89.8° 12:15	7.04	18%	61.5°
2037-04-20 Mon	0	—	unknown	—	89.8° 12:10	6.98	27%	71.2°
2037-04-21 Tue	0	—	unknown	—	89.6° 12:05	6.93	37%	81.6°
2037-04-22 Wed	0	—	unknown	—	89.7° 12:00	6.87	48%	92.3°
2037-04-23 Thu	0	—	unknown	—	89.8° 11:55	6.81	59%	103.2°
2037-04-24 Fri	0	—	unknown	—	89.7° 11:50	6.75	70%	114.0°
2037-04-25 Sat	0	—	unknown	—	89.6° 11:45	6.69	80%	124.2°
2037-04-26 Sun	1	—	unknown	—	89.6° 11:45	6.64	89%	133.0°
2037-04-27 Mon	1	—	unknown	—	89.7° 11:40	6.58	95%	139.3°
2037-04-28 Tue	1	—	unknown	—	89.8° 11:35	6.52	99%	141.7°
2037-04-29 Wed	1	—	unknown	—	89.7° 11:30	6.46	100%	139.5°
2037-04-30 Thu	1	—	unknown	—	89.5° 11:25	6.4	98%	133.6°
2037-05-01 Fri	1	—	unknown	—	89.6° 11:25	6.34	94%	125.4°
2037-05-02 Sat	1	—	unknown	—	89.8° 11:20	6.29	88%	116.1°
2037-05-03 Sun	1	—	unknown	—	89.8° 11:15	6.23	80%	106.4°
2037-05-04 Mon	1	—	unknown	—	89.6° 11:10	6.17	72%	96.5°
2037-05-05 Tue	1	—	unknown	—	89.5° 11:10	6.11	62%	86.9°
2037-05-06 Wed	1	—	unknown	—	89.7° 11:05	6.06	53%	77.4°
2037-05-07 Thu	1	—	unknown	—	89.8° 11:00	6.0	43%	68.3°
2037-05-08 Fri	2	—	unknown	—	89.7° 10:55	5.94	34%	59.8°
2037-05-09 Sat	2	—	unknown	—	89.6° 10:50	5.89	25%	52.0°
2037-05-10 Sun	3	—	unknown	04:50–05:00 (marginal, 0.17 h)	89.6° 10:50	5.83	18%	45.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-04-11&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.