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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 North America Nebula: 08-13 (100), 08-14 (100), 08-15 (100), 08-16 (100), 08-17 (100) — by astronomy; check the weather when the night is within four days.
2025-08-09astronomy score per night — click a bar for that night2025-09-07
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-08-09 Sat 64 100 64 22:20–23:30 (good, 1.17 h) 87.3° 01:05 6.31 100% 60.7°
2025-08-10 Sun 66 100 66 22:20–23:40 (good, 1.33 h) 87.2° 01:00 6.37 97% 58.4°
2025-08-11 Mon 70 100 70 22:15–00:20 (good, 2.08 h) 87.2° 01:00 6.43 92% 58.1°
2025-08-12 Tue 74 100 74 22:15–01:40 (good, 3.42 h) 87.3° 00:55 6.48 84% 59.9°
2025-08-13 Wed 100 100 100 22:10–04:00 (good, 5.83 h) 87.3° 00:50 6.54 75% 63.7°
2025-08-14 Thu 100 83 83 22:10–03:50 (good, 5.67 h) 87.2° 00:45 6.6 65% 69.1°
2025-08-15 Fri 100 99 99 22:10–04:50 (good, 6.67 h) 87.2° 00:45 6.66 53% 75.5°
2025-08-16 Sat 100 99 99 22:05–04:50 (good, 6.75 h) 87.3° 00:40 6.71 42% 82.7°
2025-08-17 Sun 100 96 96 22:05–04:50 (good, 6.75 h) 87.3° 00:35 6.77 31% 90.1°
2025-08-18 Mon 100 42 42 00:00–02:00 (good, 2.0 h) 87.3° 00:30 6.83 21% 97.5°
2025-08-19 Tue 100 0 0 — 87.2° 00:25 6.89 13% 104.4°
2025-08-20 Wed 100 99 99 22:00–04:55 (good, 6.92 h) 87.2° 00:25 6.94 6% 110.7°
2025-08-21 Thu 100 100 100 21:55–04:55 (good, 7.0 h) 87.3° 00:20 7.0 2% 115.8°
2025-08-22 Fri 100 96 96 21:55–05:00 (good, 7.08 h) 87.3° 00:15 7.06 0% 119.6°
2025-08-23 Sat 100 84 84 21:55–05:00 (good, 7.08 h) 87.3° 00:10 7.12 0% 121.6°
2025-08-24 Sun 100 92 92 22:00–05:00 (good, 7.0 h) 87.2° 00:05 7.17 3% 122.0°
2025-08-25 Mon 100 80 80 23:00–05:05 (good, 6.08 h) 87.2° 00:05 7.23 7% 120.6°
2025-08-26 Tue 100 51 51 01:00–05:05 (good, 4.08 h) 87.3° 00:00 7.29 13% 117.7°
2025-08-27 Wed 100 100 100 21:45–05:05 (good, 7.33 h) 87.3° 23:55 7.34 20% 113.7°
2025-08-28 Thu 100 100 100 21:45–05:05 (good, 7.33 h) 87.2° 23:50 7.4 28% 108.8°
2025-08-29 Fri 100 100 100 21:40–05:10 (good, 7.5 h) 87.2° 23:50 7.46 37% 103.2°
2025-08-30 Sat 100 62 62 23:00–04:00 (good, 5.0 h) 87.2° 23:45 7.51 47% 97.2°
2025-08-31 Sun 100 99 99 21:35–05:10 (good, 7.58 h) 87.3° 23:40 7.57 56% 90.9°
2025-09-01 Mon 100 97 97 21:35–05:10 (good, 7.58 h) 87.3° 23:35 7.62 66% 84.5°
2025-09-02 Tue 100 100 100 21:35–05:15 (good, 7.67 h) 87.2° 23:30 7.68 75% 78.1°
2025-09-03 Wed 98 36 36 02:30–03:00 (good, 0.5 h) 87.2° 23:30 7.74 83% 72.1°
2025-09-04 Thu 89 38 34 05:00–05:15 (good, 0.25 h) 87.3° 23:25 7.79 90% 66.6°
2025-09-05 Fri 81 12 9 04:00–05:20 (marginal, 1.33 h) 87.3° 23:20 7.85 96% 62.1°
2025-09-06 Sat 61 89 54 21:00–05:20 (marginal, 8.33 h) 87.3° 23:15 7.9 99% 59.0°
2025-09-07 Sun 61 0 0 — 87.2° 23:10 7.96 100% 58.0°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-08-09&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.