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: 09-21 (100), 09-22 (100), 09-23 (100), 09-24 (100), 09-25 (100) — by astronomy; check the weather when the night is within four days.

2038-09-12astronomy score per night — click a bar for that night2038-10-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-09-12 Sun	63	—	unknown	04:40–05:25 (good, 0.75 h)	89.5° 02:40	8.22	100%	56.5°
2038-09-13 Mon	54	—	unknown	21:10–05:30 (marginal, 8.33 h)	89.7° 02:35	8.27	100%	48.8°
2038-09-14 Tue	49	—	unknown	21:10–05:30 (marginal, 8.33 h)	89.8° 02:30	8.32	98%	42.7°
2038-09-15 Wed	52	—	unknown	21:10–05:30 (marginal, 8.33 h)	89.7° 02:25	8.38	94%	38.9°
2038-09-16 Thu	83	—	unknown	21:05–21:20 (good, 0.25 h)	89.6° 02:20	8.43	89%	38.1°
2038-09-17 Fri	86	—	unknown	21:05–22:45 (good, 1.67 h)	89.6° 02:20	8.48	83%	40.3°
2038-09-18 Sat	90	—	unknown	21:00–01:10 (good, 4.17 h)	89.7° 02:15	8.53	75%	45.1°
2038-09-19 Sun	94	—	unknown	21:00–04:25 (good, 7.42 h)	89.8° 02:10	8.59	67%	51.8°
2038-09-20 Mon	99	—	unknown	21:00–05:35 (good, 8.58 h)	89.7° 02:05	8.64	57%	59.8°
2038-09-21 Tue	100	—	unknown	20:55–05:35 (good, 8.67 h)	89.5° 02:00	8.69	48%	68.7°
2038-09-22 Wed	100	—	unknown	20:55–05:40 (good, 8.75 h)	89.6° 02:00	8.74	38%	78.2°
2038-09-23 Thu	100	—	unknown	20:50–05:40 (good, 8.83 h)	89.8° 01:55	8.79	28%	88.3°
2038-09-24 Fri	100	—	unknown	20:50–05:40 (good, 8.83 h)	89.8° 01:50	8.84	19%	98.8°
2038-09-25 Sat	100	—	unknown	20:50–05:40 (good, 8.83 h)	89.6° 01:45	8.89	11%	109.4°
2038-09-26 Sun	100	—	unknown	20:45–05:45 (good, 9.0 h)	89.5° 01:45	8.94	5%	119.8°
2038-09-27 Mon	100	—	unknown	20:45–05:45 (good, 9.0 h)	89.7° 01:40	8.99	1%	129.4°
2038-09-28 Tue	100	—	unknown	20:45–05:45 (good, 9.0 h)	89.8° 01:35	9.04	0%	137.2°
2038-09-29 Wed	100	—	unknown	20:40–05:45 (good, 9.08 h)	89.7° 01:30	9.09	2%	141.6°
2038-09-30 Thu	100	—	unknown	20:40–05:50 (good, 9.17 h)	89.6° 01:25	9.14	7%	141.2°
2038-10-01 Fri	100	—	unknown	20:40–05:50 (good, 9.17 h)	89.6° 01:25	9.18	14%	136.3°
2038-10-02 Sat	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.7° 01:20	9.23	23%	128.3°
2038-10-03 Sun	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.8° 01:15	9.28	34%	118.7°
2038-10-04 Mon	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.7° 01:10	9.33	45%	108.4°
2038-10-05 Tue	100	—	unknown	20:30–05:55 (good, 9.42 h)	89.5° 01:05	9.37	56%	97.9°
2038-10-06 Wed	100	—	unknown	20:30–05:55 (good, 9.42 h)	89.6° 01:05	9.42	66%	87.6°
2038-10-07 Thu	100	—	unknown	20:25–05:55 (good, 9.5 h)	89.8° 01:00	9.47	75%	77.4°
2038-10-08 Fri	100	—	unknown	20:40–05:55 (good, 9.25 h)	89.8° 00:55	9.51	83%	67.8°
2038-10-09 Sat	94	—	unknown	00:55–06:00 (good, 5.08 h)	89.7° 00:50	9.56	90%	58.8°
2038-10-10 Sun	86	—	unknown	05:25–06:00 (good, 0.58 h)	89.5° 00:50	9.6	95%	50.7°
2038-10-11 Mon	52	—	unknown	20:20–06:00 (marginal, 9.67 h)	89.7° 00:45	9.65	98%	44.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-09-12&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.