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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: 08-19 (100), 08-20 (100), 08-21 (100), 08-22 (100), 08-23 (100) — by astronomy; check the weather when the night is within four days.
2025-08-19astronomy score per night — click a bar for that night2025-09-17
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-08-19 Tue 100 0 0 — 89.7° 04:10 6.89 13% 77.4°
2025-08-20 Wed 100 100 100 22:05–04:55 (good, 6.83 h) 89.6° 04:05 6.94 6% 89.2°
2025-08-21 Thu 100 100 100 22:00–04:55 (good, 6.92 h) 89.5° 04:05 7.0 2% 100.9°
2025-08-22 Fri 100 97 97 22:25–05:00 (good, 6.58 h) 89.6° 04:00 7.06 0% 112.2°
2025-08-23 Sat 100 86 86 00:00–05:00 (good, 5.0 h) 89.7° 03:55 7.12 0% 122.9°
2025-08-24 Sun 100 94 94 22:00–05:00 (good, 7.0 h) 89.7° 03:50 7.17 3% 132.7°
2025-08-25 Mon 100 83 83 23:00–05:05 (good, 6.08 h) 89.5° 03:45 7.23 7% 141.2°
2025-08-26 Tue 100 57 57 01:00–05:05 (good, 4.08 h) 89.6° 03:45 7.29 13% 147.3°
2025-08-27 Wed 100 100 100 21:45–05:05 (good, 7.33 h) 89.7° 03:40 7.34 20% 150.0°
2025-08-28 Thu 100 100 100 21:45–05:05 (good, 7.33 h) 89.7° 03:35 7.4 28% 148.6°
2025-08-29 Fri 100 100 100 21:40–05:10 (good, 7.5 h) 89.6° 03:30 7.46 37% 143.5°
2025-08-30 Sat 100 61 61 23:00–04:00 (good, 5.0 h) 89.5° 03:25 7.51 47% 136.0°
2025-08-31 Sun 100 100 100 21:35–05:10 (good, 7.58 h) 89.6° 03:25 7.57 56% 127.2°
2025-09-01 Mon 100 97 97 22:00–05:10 (good, 7.17 h) 89.7° 03:20 7.62 66% 117.4°
2025-09-02 Tue 100 100 100 21:35–05:15 (good, 7.67 h) 89.7° 03:15 7.68 75% 107.0°
2025-09-03 Wed 100 38 38 02:00–03:00 (good, 1.0 h) 89.6° 03:10 7.74 83% 96.1°
2025-09-04 Thu 100 40 40 04:00–05:15 (good, 1.25 h) 89.5° 03:10 7.79 90% 84.8°
2025-09-05 Fri 100 14 14 04:55–05:00 (good, 0.08 h) 89.6° 03:05 7.85 96% 73.2°
2025-09-06 Sat 67 88 59 05:00–05:20 (good, 0.33 h) 89.7° 03:00 7.9 99% 61.6°
2025-09-07 Sun 55 0 0 — 89.7° 02:55 7.96 100% 50.3°
2025-09-08 Mon 40 55 22 01:00–05:20 (marginal, 4.33 h) 89.5° 02:50 8.01 98% 40.1°
2025-09-09 Tue 39 98 38 21:20–05:25 (marginal, 8.08 h) 89.5° 02:50 8.06 94% 32.6°
2025-09-10 Wed 47 60 28 22:00–00:15 (marginal, 2.25 h) 89.7° 02:45 8.12 87% 29.9°
2025-09-11 Thu 82 29 24 02:00–05:00 (marginal, 3.0 h) 89.7° 02:40 8.17 78% 33.4°
2025-09-12 Fri 86 31 26 21:15–22:00 (good, 0.75 h) 89.6° 02:35 8.23 67% 41.4°
2025-09-13 Sat 92 95 87 22:00–05:30 (good, 7.5 h) 89.5° 02:30 8.28 56% 51.7°
2025-09-14 Sun 99 33 33 02:00–04:00 (good, 2.0 h) 89.6° 02:30 8.33 44% 62.9°
2025-09-15 Mon 100 100 100 21:05–05:30 (good, 8.42 h) 89.7° 02:25 8.38 34% 74.5°
2025-09-16 Tue 100 100 100 21:05–05:30 (good, 8.42 h) 89.7° 02:20 8.44 24% 86.2°
2025-09-17 Wed 100 92 92 21:05–05:35 (good, 8.5 h) 89.6° 02:15 8.49 15% 97.7°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-08-19&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.