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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 Vega: 09-20 (100), 09-21 (100), 09-22 (100), 09-23 (100), 09-24 (100) — by astronomy; check the weather when the night is within four days.
2025-09-20astronomy score per night — click a bar for that night2025-10-19
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-09-20 Sat 100 63 63 21:00–23:00 (good, 2.0 h) 87.1° 20:00 8.64 1% 102.6°
2025-09-21 Sun 100 100 100 20:55–01:55 (good, 5.0 h) 87.1° 19:55 8.7 0% 98.0°
2025-09-22 Mon 100 100 100 20:55–01:50 (good, 4.92 h) 87.1° 19:50 8.75 1% 93.2°
2025-09-23 Tue 100 99 99 20:50–01:45 (good, 4.92 h) 87.1° 19:50 8.8 4% 88.4°
2025-09-24 Wed 100 97 97 20:50–01:45 (good, 4.92 h) 87.1° 19:45 8.85 9% 83.6°
2025-09-25 Thu 100 0 0 — 87.1° 19:40 8.9 15% 79.2°
2025-09-26 Fri 100 18 18 00:00–01:35 (marginal, 1.58 h) 87.1° 19:35 8.95 22% 75.1°
2025-09-27 Sat 100 25 25 20:45–21:00 (good, 0.25 h) 87.1° 19:30 9.0 31% 71.7°
2025-09-28 Sun 99 0 0 — 87.1° 19:30 9.05 40% 68.9°
2025-09-29 Mon 92 0 0 — 87.1° 19:25 9.09 49% 67.1°
2025-09-30 Tue 84 26 22 00:00–01:00 (good, 1.0 h) 87.1° 19:20 9.14 59% 66.3°
2025-10-01 Wed 69 0 0 — 87.1° 19:15 9.19 69% 66.7°
2025-10-02 Thu 60 0 0 — 87.1° 19:10 9.24 78% 68.4°
2025-10-03 Fri 54 0 0 — 87.1° 19:10 9.29 86% 71.3°
2025-10-04 Sat 52 90 47 21:00–22:00 (good, 1.0 h) 87.1° 19:05 9.33 93% 75.3°
2025-10-05 Sun 52 74 38 20:30–21:00 (good, 0.5 h) 87.1° 19:00 9.38 98% 80.3°
2025-10-06 Mon 57 0 0 — 87.1° 18:55 9.43 100% 86.0°
2025-10-07 Tue 64 0 0 — 87.1° 18:55 9.47 99% 92.0°
2025-10-08 Wed 72 0 0 — 87.1° 18:50 9.52 95% 98.0°
2025-10-09 Thu 81 93 76 20:25–00:20 (good, 3.92 h) 87.1° 18:45 9.57 89% 103.4°
2025-10-10 Fri 100 92 92 20:20–00:20 (good, 4.0 h) 87.1° 18:40 9.61 80% 107.9°
2025-10-11 Sat 100 55 55 20:20–22:00 (good, 1.67 h) 87.1° 18:35 9.66 70% 111.3°
2025-10-12 Sun 100 22 22 00:00–00:55 (marginal, 0.92 h) 87.1° 18:35 9.7 59% 113.2°
2025-10-13 Mon 100 7 7 — 87.1° 18:30 9.74 48% 113.7°
2025-10-14 Tue 100 0 0 — 87.1° 18:25 9.79 38% 112.8°
2025-10-15 Wed 100 16 16 23:00–00:00 (good, 1.0 h) 87.1° 18:20 9.83 28% 110.7°
2025-10-16 Thu 100 0 0 — 87.1° 18:15 9.87 19% 107.6°
2025-10-17 Fri 100 0 0 — 87.1° 18:15 9.92 12% 103.7°
2025-10-18 Sat 100 0 0 — 87.1° 18:10 9.96 6% 99.3°
2025-10-19 Sun 100 0 0 — 87.1° 18:05 10.0 2% 94.6°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-09-20&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.