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: 08-20 (100), 08-21 (100), 08-22 (100), 08-23 (100), 08-24 (100) — by astronomy; check the weather when the night is within four days.

2039-08-20astronomy score per night — click a bar for that night2039-09-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-08-20 Sat	100	—	unknown	22:05–04:55 (good, 6.83 h)	89.7° 04:10	6.92	1%	121.2°
2039-08-21 Sun	100	—	unknown	22:00–04:55 (good, 6.92 h)	89.8° 04:05	6.98	5%	130.0°
2039-08-22 Mon	100	—	unknown	21:55–05:00 (good, 7.08 h)	89.7° 04:00	7.04	11%	137.3°
2039-08-23 Tue	100	—	unknown	21:55–05:00 (good, 7.08 h)	89.5° 03:55	7.09	18%	141.9°
2039-08-24 Wed	100	—	unknown	21:50–05:00 (good, 7.17 h)	89.6° 03:55	7.15	28%	142.5°
2039-08-25 Thu	100	—	unknown	21:50–05:00 (good, 7.17 h)	89.8° 03:50	7.21	38%	138.9°
2039-08-26 Fri	100	—	unknown	21:50–05:05 (good, 7.25 h)	89.8° 03:45	7.26	50%	132.0°
2039-08-27 Sat	100	—	unknown	21:45–05:05 (good, 7.33 h)	89.6° 03:40	7.32	61%	122.9°
2039-08-28 Sun	100	—	unknown	21:45–05:05 (good, 7.33 h)	89.5° 03:40	7.38	72%	112.5°
2039-08-29 Mon	100	—	unknown	21:50–05:10 (good, 7.33 h)	89.7° 03:35	7.43	82%	101.4°
2039-08-30 Tue	100	—	unknown	21:55–05:10 (good, 7.25 h)	89.8° 03:30	7.49	90%	90.1°
2039-08-31 Wed	100	—	unknown	22:55–05:10 (good, 6.25 h)	89.7° 03:25	7.55	95%	78.9°
2039-09-01 Thu	70	—	unknown	00:35–05:10 (good, 4.58 h)	89.6° 03:20	7.6	99%	68.0°
2039-09-02 Fri	61	—	unknown	05:05–05:15 (good, 0.17 h)	89.6° 03:20	7.66	100%	57.9°
2039-09-03 Sat	51	—	unknown	21:30–05:15 (marginal, 7.75 h)	89.7° 03:15	7.71	98%	49.1°
2039-09-04 Sun	49	—	unknown	21:30–05:15 (marginal, 7.75 h)	89.8° 03:10	7.77	95%	42.2°
2039-09-05 Mon	79	—	unknown	21:30–21:35 (good, 0.08 h)	89.7° 03:05	7.82	89%	38.0°
2039-09-06 Tue	83	—	unknown	21:25–22:00 (good, 0.58 h)	89.5° 03:00	7.88	82%	37.3°
2039-09-07 Wed	86	—	unknown	21:25–01:00 (good, 3.58 h)	89.6° 03:00	7.93	74%	39.9°
2039-09-08 Thu	90	—	unknown	21:20–03:35 (good, 6.25 h)	89.8° 02:55	7.99	65%	45.2°
2039-09-09 Fri	94	—	unknown	21:20–05:20 (good, 8.0 h)	89.8° 02:50	8.04	56%	52.3°
2039-09-10 Sat	99	—	unknown	21:20–05:25 (good, 8.08 h)	89.7° 02:45	8.1	47%	60.4°
2039-09-11 Sun	100	—	unknown	21:15–05:25 (good, 8.17 h)	89.5° 02:45	8.15	37%	69.2°
2039-09-12 Mon	100	—	unknown	21:15–05:25 (good, 8.17 h)	89.7° 02:40	8.2	28%	78.6°
2039-09-13 Tue	100	—	unknown	21:10–05:25 (good, 8.25 h)	89.8° 02:35	8.26	20%	88.2°
2039-09-14 Wed	100	—	unknown	21:10–05:30 (good, 8.33 h)	89.8° 02:30	8.31	13%	98.1°
2039-09-15 Thu	100	—	unknown	21:10–05:30 (good, 8.33 h)	89.6° 02:25	8.36	7%	108.1°
2039-09-16 Fri	100	—	unknown	21:05–05:30 (good, 8.42 h)	89.6° 02:25	8.42	3%	117.9°
2039-09-17 Sat	100	—	unknown	21:05–05:30 (good, 8.42 h)	89.7° 02:20	8.47	0%	127.2°
2039-09-18 Sun	100	—	unknown	21:00–05:35 (good, 8.58 h)	89.8° 02:15	8.52	1%	135.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-08-20&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.