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: 08-03 (100), 08-04 (100), 08-05 (100), 08-06 (100), 08-07 (100) — by astronomy; check the weather when the night is within four days.

2040-07-27astronomy score per night — click a bar for that night2040-08-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-07-27 Fri	44	—	unknown	23:05–04:20 (marginal, 5.25 h)	89.8° 05:40	5.61	80%	46.7°
2040-07-28 Sat	55	—	unknown	02:40–03:00 (good, 0.33 h)	89.6° 05:35	5.66	70%	39.8°
2040-07-29 Sun	76	—	unknown	23:30–04:20 (good, 4.83 h)	89.5° 05:35	5.72	60%	36.3°
2040-07-30 Mon	84	—	unknown	23:25–04:25 (good, 5.0 h)	89.7° 05:30	5.77	49%	36.8°
2040-07-31 Tue	87	—	unknown	23:20–04:25 (good, 5.08 h)	89.8° 05:25	5.83	39%	40.8°
2040-08-01 Wed	91	—	unknown	23:15–04:25 (good, 5.17 h)	89.7° 05:20	5.88	30%	47.3°
2040-08-02 Thu	96	—	unknown	23:15–04:30 (good, 5.25 h)	89.6° 05:15	5.94	22%	55.1°
2040-08-03 Fri	100	—	unknown	23:10–04:30 (good, 5.33 h)	89.6° 05:15	5.99	14%	63.8°
2040-08-04 Sat	100	—	unknown	23:05–04:30 (good, 5.42 h)	89.7° 05:10	6.05	8%	73.0°
2040-08-05 Sun	100	—	unknown	23:00–04:35 (good, 5.58 h)	89.8° 05:05	6.1	4%	82.4°
2040-08-06 Mon	100	—	unknown	22:55–04:35 (good, 5.67 h)	89.7° 05:00	6.16	1%	92.0°
2040-08-07 Tue	100	—	unknown	22:55–04:35 (good, 5.67 h)	89.5° 04:55	6.22	0%	101.6°
2040-08-08 Wed	100	—	unknown	22:50–04:40 (good, 5.83 h)	89.6° 04:55	6.28	1%	111.0°
2040-08-09 Thu	100	—	unknown	22:45–04:40 (good, 5.92 h)	89.8° 04:50	6.33	4%	120.2°
2040-08-10 Fri	100	—	unknown	22:40–04:40 (good, 6.0 h)	89.8° 04:45	6.39	8%	128.7°
2040-08-11 Sat	100	—	unknown	22:40–04:40 (good, 6.0 h)	89.7° 04:40	6.45	14%	136.2°
2040-08-12 Sun	100	—	unknown	22:35–04:45 (good, 6.17 h)	89.5° 04:40	6.5	22%	141.7°
2040-08-13 Mon	100	—	unknown	22:30–04:45 (good, 6.25 h)	89.7° 04:35	6.56	31%	144.1°
2040-08-14 Tue	100	—	unknown	22:30–04:45 (good, 6.25 h)	89.8° 04:30	6.62	41%	142.6°
2040-08-15 Wed	100	—	unknown	22:25–04:50 (good, 6.42 h)	89.8° 04:25	6.68	52%	137.3°
2040-08-16 Thu	100	—	unknown	22:25–04:50 (good, 6.42 h)	89.6° 04:20	6.73	63%	129.3°
2040-08-17 Fri	100	—	unknown	22:25–04:50 (good, 6.42 h)	89.6° 04:20	6.79	73%	119.3°
2040-08-18 Sat	100	—	unknown	22:25–04:55 (good, 6.5 h)	89.7° 04:15	6.85	83%	108.2°
2040-08-19 Sun	100	—	unknown	22:30–04:55 (good, 6.42 h)	89.8° 04:10	6.91	91%	96.3°
2040-08-20 Mon	100	—	unknown	23:05–04:55 (good, 5.83 h)	89.7° 04:05	6.96	97%	84.1°
2040-08-21 Tue	70	—	unknown	00:40–04:55 (good, 4.25 h)	89.5° 04:00	7.02	100%	72.1°
2040-08-22 Wed	60	—	unknown	21:55–05:35 (marginal, 7.67 h)	89.6° 04:00	7.08	99%	60.6°
2040-08-23 Thu	48	—	unknown	21:50–05:00 (marginal, 7.17 h)	89.8° 03:55	7.14	96%	50.3°
2040-08-24 Fri	48	—	unknown	21:50–05:00 (marginal, 7.17 h)	89.8° 03:50	7.19	91%	42.1°
2040-08-25 Sat	75	—	unknown	21:50–22:10 (good, 0.33 h)	89.7° 03:45	7.25	84%	37.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-27&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.