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: 05-07 (2), 05-08 (2), 05-09 (2), 05-10 (2), 05-11 (2) — by astronomy; check the weather when the night is within four days.

2039-04-13astronomy score per night — click a bar for that night2039-05-12

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-13 Wed	0	—	unknown	—	89.8° 12:40	7.42	70%	113.2°
2039-04-14 Thu	0	—	unknown	—	89.7° 12:35	7.36	59%	102.3°
2039-04-15 Fri	0	—	unknown	—	89.5° 12:30	7.3	48%	91.4°
2039-04-16 Sat	0	—	unknown	—	89.6° 12:30	7.24	37%	80.8°
2039-04-17 Sun	0	—	unknown	—	89.8° 12:25	7.19	27%	70.5°
2039-04-18 Mon	0	—	unknown	—	89.8° 12:20	7.13	19%	60.9°
2039-04-19 Tue	0	—	unknown	—	89.6° 12:15	7.07	12%	52.3°
2039-04-20 Wed	0	—	unknown	—	89.5° 12:15	7.01	6%	45.1°
2039-04-21 Thu	0	—	unknown	—	89.7° 12:10	6.95	2%	39.9°
2039-04-22 Fri	0	—	unknown	—	89.8° 12:05	6.9	0%	37.6°
2039-04-23 Sat	0	—	unknown	—	89.7° 12:00	6.84	0%	38.5°
2039-04-24 Sun	0	—	unknown	—	89.6° 11:55	6.78	2%	42.3°
2039-04-25 Mon	0	—	unknown	—	89.7° 11:50	6.72	6%	48.4°
2039-04-26 Tue	0	—	unknown	—	89.8° 11:45	6.66	11%	55.8°
2039-04-27 Wed	1	—	unknown	—	89.7° 11:40	6.6	17%	64.2°
2039-04-28 Thu	1	—	unknown	—	89.5° 11:35	6.55	25%	73.2°
2039-04-29 Fri	1	—	unknown	—	89.6° 11:35	6.49	34%	82.6°
2039-04-30 Sat	1	—	unknown	—	89.8° 11:30	6.43	43%	92.3°
2039-05-01 Sun	1	—	unknown	—	89.8° 11:25	6.37	53%	102.2°
2039-05-02 Mon	1	—	unknown	—	89.6° 11:20	6.31	64%	112.1°
2039-05-03 Tue	1	—	unknown	—	89.5° 11:20	6.26	74%	121.8°
2039-05-04 Wed	1	—	unknown	—	89.7° 11:15	6.2	83%	130.8°
2039-05-05 Thu	1	—	unknown	—	89.8° 11:10	6.14	91%	138.1°
2039-05-06 Fri	1	—	unknown	—	89.7° 11:05	6.08	96%	142.1°
2039-05-07 Sat	2	—	unknown	—	89.6° 11:00	6.03	100%	141.5°
2039-05-08 Sun	2	—	unknown	—	89.6° 11:00	5.97	100%	136.2°
2039-05-09 Mon	2	—	unknown	—	89.7° 10:55	5.91	97%	127.6°
2039-05-10 Tue	2	—	unknown	—	89.8° 10:50	5.86	91%	117.2°
2039-05-11 Wed	2	—	unknown	04:10–04:15 (marginal, 0.08 h)	89.7° 10:45	5.8	83%	106.1°
2039-05-12 Thu	2	—	unknown	04:05–04:10 (marginal, 0.08 h)	89.5° 10:40	5.75	74%	94.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-13&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.