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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: 09-05 (100), 09-06 (100), 09-07 (100), 09-08 (100), 09-09 (100) — by astronomy; check the weather when the night is within four days.
2026-08-29astronomy score per night — click a bar for that night2026-09-27
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-08-29 Sat 38 16 6 21:40–23:00 (marginal, 1.33 h) 89.5° 03:30 7.44 97% 41.9°
2026-08-30 Sun 37 98 36 21:40–05:10 (marginal, 7.5 h) 89.6° 03:30 7.5 92% 33.8°
2026-08-31 Mon 44 99 44 21:35–05:10 (marginal, 7.58 h) 89.7° 03:25 7.56 85% 29.2°
2026-09-01 Tue 76 88 67 21:35–21:45 (good, 0.17 h) 89.7° 03:20 7.61 76% 30.0°
2026-09-02 Wed 84 7 6 — 89.6° 03:15 7.67 66% 36.1°
2026-09-03 Thu 89 87 78 00:00–03:00 (good, 3.0 h) 89.5° 03:15 7.72 55% 45.4°
2026-09-04 Fri 95 97 92 21:30–05:15 (good, 7.75 h) 89.6° 03:10 7.78 43% 56.4°
2026-09-05 Sat 100 100 100 21:25–05:15 (good, 7.83 h) 89.7° 03:05 7.83 32% 68.3°
2026-09-06 Sun 100 99 99 21:25–05:20 (good, 7.92 h) 89.7° 03:00 7.89 22% 80.7°
2026-09-07 Mon 100 100 100 21:25–05:20 (good, 7.92 h) 89.5° 02:55 7.94 13% 93.2°
2026-09-08 Tue 100 100 100 21:20–05:20 (good, 8.0 h) 89.5° 02:55 8.0 6% 105.6°
2026-09-09 Wed 100 85 85 21:20–05:00 (good, 7.67 h) 89.7° 02:50 8.05 2% 117.7°
2026-09-10 Thu 100 100 100 21:15–05:25 (good, 8.17 h) 89.7° 02:45 8.11 0% 129.1°
2026-09-11 Fri 100 99 99 21:15–05:25 (good, 8.17 h) 89.6° 02:40 8.16 1% 139.1°
2026-09-12 Sat 100 0 0 — 89.5° 02:35 8.21 4% 146.9°
2026-09-13 Sun 100 88 88 21:10–05:30 (good, 8.33 h) 89.6° 02:35 8.27 9% 150.9°
2026-09-14 Mon 100 37 37 00:00–03:00 (good, 3.0 h) 89.7° 02:30 8.32 15% 149.9°
2026-09-15 Tue 100 75 75 23:15–05:30 (good, 6.25 h) 89.7° 02:25 8.37 23% 144.7°
2026-09-16 Wed 100 97 97 21:05–05:30 (good, 8.42 h) 89.6° 02:20 8.42 32% 137.0°
2026-09-17 Thu 100 100 100 21:05–05:30 (good, 8.42 h) 89.5° 02:20 8.48 41% 128.0°
2026-09-18 Fri 100 87 87 21:15–05:35 (good, 8.33 h) 89.6° 02:15 8.53 51% 118.4°
2026-09-19 Sat 100 83 83 21:00–03:00 (good, 6.0 h) 89.7° 02:10 8.58 60% 108.3°
2026-09-20 Sun 100 98 98 21:00–05:35 (good, 8.58 h) 89.7° 02:05 8.63 69% 98.0°
2026-09-21 Mon 100 0 0 — 89.5° 02:00 8.68 78% 87.4°
2026-09-22 Tue 100 32 32 04:00–05:40 (good, 1.67 h) 89.5° 02:00 8.73 85% 76.7°
2026-09-23 Wed 100 92 92 01:50–05:40 (good, 3.83 h) 89.7° 01:55 8.78 92% 65.9°
2026-09-24 Thu 92 72 66 03:55–04:00 (good, 0.08 h) 89.7° 01:50 8.84 96% 55.2°
2026-09-25 Fri 54 2 1 — 89.6° 01:45 8.89 99% 45.0°
2026-09-26 Sat 38 0 0 — 89.5° 01:40 8.94 100% 36.1°
2026-09-27 Sun 34 70 24 21:00–22:00 (marginal, 1.0 h) 89.6° 01:40 8.98 98% 30.2°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-08-29&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.