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: 09-09 (100), 09-10 (100), 09-11 (100), 09-12 (100), 09-13 (100) — by astronomy; check the weather when the night is within four days.

2031-09-06astronomy score per night — click a bar for that night2031-10-05

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-09-06 Sat	88	—	unknown	21:25–02:35 (good, 5.17 h)	89.5° 03:00	7.88	67%	41.9°
2031-09-07 Sun	93	—	unknown	21:25–05:20 (good, 7.92 h)	89.6° 03:00	7.93	57%	50.4°
2031-09-08 Mon	99	—	unknown	21:20–05:20 (good, 8.0 h)	89.7° 02:55	7.99	48%	59.8°
2031-09-09 Tue	100	—	unknown	21:20–05:20 (good, 8.0 h)	89.7° 02:50	8.04	38%	69.6°
2031-09-10 Wed	100	—	unknown	21:20–05:25 (good, 8.08 h)	89.7° 02:45	8.09	29%	79.6°
2031-09-11 Thu	100	—	unknown	21:15–05:25 (good, 8.17 h)	89.5° 02:40	8.15	21%	89.7°
2031-09-12 Fri	100	—	unknown	21:15–05:25 (good, 8.17 h)	89.6° 02:40	8.2	14%	99.8°
2031-09-13 Sat	100	—	unknown	21:10–05:25 (good, 8.25 h)	89.7° 02:35	8.26	8%	109.9°
2031-09-14 Sun	100	—	unknown	21:10–05:30 (good, 8.33 h)	89.7° 02:30	8.31	4%	119.9°
2031-09-15 Mon	100	—	unknown	21:10–05:30 (good, 8.33 h)	89.6° 02:25	8.36	1%	129.4°
2031-09-16 Tue	100	—	unknown	21:05–05:30 (good, 8.42 h)	89.5° 02:25	8.41	0%	138.1°
2031-09-17 Wed	100	—	unknown	21:05–05:30 (good, 8.42 h)	89.7° 02:20	8.47	2%	144.9°
2031-09-18 Thu	100	—	unknown	21:00–05:35 (good, 8.58 h)	89.7° 02:15	8.52	5%	148.5°
2031-09-19 Fri	100	—	unknown	21:00–05:35 (good, 8.58 h)	89.7° 02:10	8.57	10%	147.4°
2031-09-20 Sat	100	—	unknown	21:00–05:35 (good, 8.58 h)	89.6° 02:05	8.62	18%	141.9°
2031-09-21 Sun	100	—	unknown	20:55–05:35 (good, 8.67 h)	89.6° 02:05	8.67	27%	133.4°
2031-09-22 Mon	100	—	unknown	20:55–05:40 (good, 8.75 h)	89.7° 02:00	8.72	37%	123.1°
2031-09-23 Tue	100	—	unknown	20:55–05:40 (good, 8.75 h)	89.7° 01:55	8.77	48%	111.8°
2031-09-24 Wed	100	—	unknown	20:50–05:40 (good, 8.83 h)	89.7° 01:50	8.82	60%	99.9°
2031-09-25 Thu	100	—	unknown	20:50–05:40 (good, 8.83 h)	89.5° 01:45	8.87	71%	87.7°
2031-09-26 Fri	100	—	unknown	21:00–05:45 (good, 8.75 h)	89.6° 01:45	8.92	81%	75.5°
2031-09-27 Sat	100	—	unknown	23:55–05:45 (good, 5.83 h)	89.7° 01:40	8.97	89%	63.5°
2031-09-28 Sun	91	—	unknown	03:50–05:45 (good, 1.92 h)	89.7° 01:35	9.02	95%	52.1°
2031-09-29 Mon	52	—	unknown	20:40–05:45 (marginal, 9.08 h)	89.6° 01:30	9.07	99%	42.1°
2031-09-30 Tue	37	—	unknown	20:40–05:45 (marginal, 9.08 h)	89.5° 01:30	9.12	100%	34.7°
2031-10-01 Wed	36	—	unknown	20:40–00:35 (marginal, 3.92 h)	89.7° 01:25	9.17	98%	31.4°
2031-10-02 Thu	47	—	unknown	20:35–05:50 (marginal, 9.25 h)	89.7° 01:20	9.22	95%	33.2°
2031-10-03 Fri	58	—	unknown	20:00–05:50 (marginal, 9.83 h)	89.7° 01:15	9.27	89%	39.1°
2031-10-04 Sat	90	—	unknown	20:35–23:50 (good, 3.25 h)	89.6° 01:10	9.31	82%	47.3°
2031-10-05 Sun	97	—	unknown	20:30–02:55 (good, 6.42 h)	89.5° 01:10	9.36	73%	56.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-09-06&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.