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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: 08-09 (100), 08-10 (100), 08-11 (100), 08-12 (100), 08-13 (100) — by astronomy; check the weather when the night is within four days.
2026-07-31astronomy score per night — click a bar for that night2026-08-29
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-07-31 Fri 42 100 42 23:00–04:25 (marginal, 5.42 h) 89.6° 05:25 5.79 95% 59.1°
2026-08-01 Sat 37 100 37 22:55–04:25 (marginal, 5.5 h) 89.5° 05:20 5.85 89% 48.9°
2026-08-02 Sun 37 99 37 22:50–04:25 (marginal, 5.58 h) 89.6° 05:20 5.9 82% 39.6°
2026-08-03 Mon 42 99 42 22:40–04:30 (marginal, 5.83 h) 89.7° 05:15 5.96 73% 32.3°
2026-08-04 Tue 58 96 56 22:35–04:30 (marginal, 5.92 h) 89.7° 05:10 6.01 63% 28.9°
2026-08-05 Wed 81 93 75 00:05–04:30 (good, 4.42 h) 89.6° 05:05 6.07 52% 31.0°
2026-08-06 Thu 85 90 77 23:10–04:35 (good, 5.42 h) 89.5° 05:05 6.13 40% 38.0°
2026-08-07 Fri 91 98 89 23:00–04:35 (good, 5.58 h) 89.6° 05:00 6.18 30% 48.0°
2026-08-08 Sat 98 75 74 23:00–03:00 (good, 4.0 h) 89.7° 04:55 6.24 19% 59.6°
2026-08-09 Sun 100 95 95 23:00–04:40 (good, 5.67 h) 89.7° 04:50 6.3 11% 72.0°
2026-08-10 Mon 100 99 99 22:45–04:40 (good, 5.92 h) 89.5° 04:45 6.35 5% 84.9°
2026-08-11 Tue 100 100 100 22:40–04:40 (good, 6.0 h) 89.6° 04:45 6.41 1% 97.7°
2026-08-12 Wed 100 97 97 22:40–04:45 (good, 6.08 h) 89.7° 04:40 6.47 0% 110.3°
2026-08-13 Thu 100 25 25 23:00–00:00 (good, 1.0 h) 89.7° 04:35 6.53 2% 122.4°
2026-08-14 Fri 100 66 66 22:35–02:00 (good, 3.42 h) 89.6° 04:30 6.58 6% 133.4°
2026-08-15 Sat 100 100 100 22:25–04:45 (good, 6.33 h) 89.5° 04:25 6.64 12% 142.6°
2026-08-16 Sun 100 100 100 22:20–04:50 (good, 6.5 h) 89.6° 04:25 6.7 20% 149.1°
2026-08-17 Mon 100 100 100 22:15–04:50 (good, 6.58 h) 89.7° 04:20 6.76 29% 151.2°
2026-08-18 Tue 100 60 60 23:25–02:00 (good, 2.58 h) 89.7° 04:15 6.81 39% 148.5°
2026-08-19 Wed 100 100 100 22:15–04:55 (good, 6.67 h) 89.6° 04:10 6.87 48% 142.3°
2026-08-20 Thu 100 99 99 22:10–04:55 (good, 6.75 h) 89.5° 04:10 6.93 58% 134.1°
2026-08-21 Fri 100 100 100 22:05–04:55 (good, 6.83 h) 89.6° 04:05 6.99 67% 124.9°
2026-08-22 Sat 100 91 91 01:00–05:00 (good, 4.0 h) 89.7° 04:00 7.04 76% 115.1°
2026-08-23 Sun 100 85 85 23:00–05:00 (good, 6.0 h) 89.7° 03:55 7.1 83% 104.9°
2026-08-24 Mon 100 57 57 02:00–05:00 (good, 3.0 h) 89.5° 03:50 7.16 90% 94.4°
2026-08-25 Tue 100 98 98 23:10–05:00 (good, 5.83 h) 89.5° 03:50 7.22 95% 83.7°
2026-08-26 Wed 73 95 69 00:45–05:05 (good, 4.33 h) 89.7° 03:45 7.27 98% 72.9°
2026-08-27 Thu 63 97 61 04:35–05:05 (good, 0.5 h) 89.7° 03:40 7.33 100% 62.1°
2026-08-28 Fri 50 92 46 21:45–05:05 (marginal, 7.33 h) 89.6° 03:35 7.39 99% 51.6°
2026-08-29 Sat 38 16 6 21:40–23:00 (marginal, 1.33 h) 89.5° 03:30 7.44 97% 41.9°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-07-31&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.