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: 03-13 (5), 03-14 (4), 03-15 (3), 03-16 (2), 03-17 (1) — by astronomy; check the weather when the night is within four days.

2040-03-13astronomy score per night — click a bar for that night2040-04-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-03-13 Tue	5	—	unknown	20:00–20:20 (marginal, 0.33 h)	89.7° 13:40	9.05	1%	43.5°
2040-03-14 Wed	4	—	unknown	20:00–20:15 (marginal, 0.25 h)	89.8° 13:35	9.0	4%	38.1°
2040-03-15 Thu	3	—	unknown	20:05–20:15 (marginal, 0.17 h)	89.7° 13:30	8.95	10%	36.4°
2040-03-16 Fri	2	—	unknown	20:05–20:10 (marginal, 0.08 h)	89.5° 13:25	8.9	16%	38.6°
2040-03-17 Sat	1	—	unknown	—	89.6° 13:25	8.84	24%	43.8°
2040-03-18 Sun	1	—	unknown	—	89.8° 13:20	8.79	33%	50.9°
2040-03-19 Mon	1	—	unknown	—	89.8° 13:15	8.74	42%	59.2°
2040-03-20 Tue	0	—	unknown	—	89.6° 13:10	8.69	52%	68.1°
2040-03-21 Wed	0	—	unknown	—	89.5° 13:10	8.64	61%	77.3°
2040-03-22 Thu	0	—	unknown	—	89.7° 13:05	8.59	70%	86.8°
2040-03-23 Fri	0	—	unknown	—	89.8° 13:00	8.53	78%	96.5°
2040-03-24 Sat	0	—	unknown	—	89.7° 12:55	8.48	86%	106.2°
2040-03-25 Sun	0	—	unknown	—	89.6° 13:50	8.43	92%	115.8°
2040-03-26 Mon	0	—	unknown	—	89.6° 13:50	8.37	97%	125.0°
2040-03-27 Tue	0	—	unknown	—	89.7° 13:45	8.32	99%	133.4°
2040-03-28 Wed	0	—	unknown	—	89.8° 13:40	8.27	100%	139.9°
2040-03-29 Thu	0	—	unknown	—	89.7° 13:35	8.21	98%	143.4°
2040-03-30 Fri	0	—	unknown	—	89.5° 13:30	8.16	94%	142.7°
2040-03-31 Sat	0	—	unknown	—	89.6° 13:30	8.1	87%	137.8°
2040-04-01 Sun	0	—	unknown	—	89.8° 13:25	8.05	79%	129.9°
2040-04-02 Mon	0	—	unknown	—	89.8° 13:20	7.99	68%	120.2°
2040-04-03 Tue	0	—	unknown	—	89.6° 13:15	7.94	57%	109.5°
2040-04-04 Wed	0	—	unknown	—	89.5° 13:15	7.88	46%	98.3°
2040-04-05 Thu	0	—	unknown	—	89.7° 13:10	7.83	35%	87.0°
2040-04-06 Fri	0	—	unknown	—	89.8° 13:05	7.77	24%	75.7°
2040-04-07 Sat	0	—	unknown	—	89.7° 13:00	7.72	16%	64.9°
2040-04-08 Sun	0	—	unknown	—	89.6° 12:55	7.66	8%	54.8°
2040-04-09 Mon	0	—	unknown	—	89.6° 12:55	7.6	3%	46.1°
2040-04-10 Tue	0	—	unknown	—	89.7° 12:50	7.55	1%	39.7°
2040-04-11 Wed	0	—	unknown	—	89.8° 12:45	7.49	0%	36.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-03-13&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.