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: 06-21 (44), 06-20 (43), 06-18 (42), 06-19 (42), 06-17 (40) — by astronomy; check the weather when the night is within four days.

2040-05-24astronomy score per night — click a bar for that night2040-06-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-05-24 Thu	9	—	unknown	03:15–03:55 (marginal, 0.67 h)	89.6° 09:50	5.1	97%	142.0°
2040-05-25 Fri	9	—	unknown	03:10–03:50 (marginal, 0.67 h)	89.6° 09:50	5.05	100%	136.0°
2040-05-26 Sat	10	—	unknown	03:05–04:40 (marginal, 1.58 h)	89.8° 09:45	5.01	100%	127.1°
2040-05-27 Sun	11	—	unknown	03:05–04:40 (marginal, 1.58 h)	89.8° 09:40	4.97	97%	116.5°
2040-05-28 Mon	11	—	unknown	03:00–04:40 (marginal, 1.67 h)	89.7° 09:35	4.93	91%	105.0°
2040-05-29 Tue	11	—	unknown	02:55–04:35 (marginal, 1.67 h)	89.5° 09:30	4.89	84%	93.1°
2040-05-30 Wed	10	—	unknown	02:50–03:45 (marginal, 0.92 h)	89.7° 09:30	4.85	74%	81.4°
2040-05-31 Thu	11	—	unknown	02:50–04:35 (marginal, 1.75 h)	89.8° 09:25	4.81	63%	70.1°
2040-06-01 Fri	13	—	unknown	03:40–03:45 (good, 0.08 h)	89.8° 09:20	4.77	52%	59.6°
2040-06-02 Sat	15	—	unknown	03:30–03:45 (good, 0.25 h)	89.6° 09:15	4.74	41%	50.2°
2040-06-03 Sun	18	—	unknown	03:20–03:45 (good, 0.42 h)	89.5° 09:15	4.71	31%	42.7°
2040-06-04 Mon	23	—	unknown	03:05–03:40 (good, 0.58 h)	89.7° 09:10	4.67	21%	37.8°
2040-06-05 Tue	24	—	unknown	03:00–03:40 (good, 0.67 h)	89.8° 09:05	4.64	14%	36.4°
2040-06-06 Wed	25	—	unknown	02:55–03:40 (good, 0.75 h)	89.7° 09:00	4.62	8%	38.7°
2040-06-07 Thu	26	—	unknown	02:55–03:40 (good, 0.75 h)	89.6° 08:55	4.59	3%	43.9°
2040-06-08 Fri	28	—	unknown	02:50–03:40 (good, 0.83 h)	89.6° 08:55	4.57	1%	51.1°
2040-06-09 Sat	29	—	unknown	02:45–03:40 (good, 0.92 h)	89.7° 08:50	4.54	0%	59.4°
2040-06-10 Sun	30	—	unknown	02:40–03:40 (good, 1.0 h)	89.8° 08:45	4.52	1%	68.4°
2040-06-11 Mon	32	—	unknown	02:35–03:40 (good, 1.08 h)	89.7° 08:40	4.5	4%	77.7°
2040-06-12 Tue	33	—	unknown	02:35–03:40 (good, 1.08 h)	89.5° 08:35	4.49	9%	87.2°
2040-06-13 Wed	35	—	unknown	02:30–03:40 (good, 1.17 h)	89.6° 08:35	4.47	15%	96.7°
2040-06-14 Thu	36	—	unknown	02:25–03:40 (good, 1.25 h)	89.8° 08:30	4.46	22%	106.1°
2040-06-15 Fri	37	—	unknown	02:20–03:40 (good, 1.33 h)	89.8° 08:25	4.45	31%	115.4°
2040-06-16 Sat	39	—	unknown	02:20–03:40 (good, 1.33 h)	89.6° 08:20	4.44	40%	124.3°
2040-06-17 Sun	40	—	unknown	02:15–03:40 (good, 1.42 h)	89.5° 08:20	4.43	50%	132.4°
2040-06-18 Mon	42	—	unknown	02:10–03:40 (good, 1.5 h)	89.7° 08:15	4.43	61%	139.0°
2040-06-19 Tue	42	—	unknown	02:10–03:40 (good, 1.5 h)	89.8° 08:10	4.42	71%	143.1°
2040-06-20 Wed	43	—	unknown	02:10–03:40 (good, 1.5 h)	89.7° 08:05	4.42	80%	143.2°
2040-06-21 Thu	44	—	unknown	02:05–03:40 (good, 1.58 h)	89.6° 08:00	4.42	88%	139.0°
2040-06-22 Fri	40	—	unknown	02:05–03:40 (good, 1.58 h)	89.6° 08:00	4.43	95%	131.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-05-24&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.