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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 V1057 Cyg: 05-05 (83), 05-19 (83), 05-02 (82), 05-06 (82), 05-07 (82) — by astronomy; check the weather when the night is within four days.
2025-04-20astronomy score per night — click a bar for that night2025-05-19
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-04-20 Sun 56 83 46 03:00–04:50 (good, 1.83 h) 87.3° 08:25 6.99 52% 69.7°
2025-04-21 Mon 63 75 47 03:00–04:00 (good, 1.0 h) 87.3° 08:20 6.93 41% 64.8°
2025-04-22 Tue 68 58 39 04:00–04:50 (good, 0.83 h) 87.3° 08:15 6.87 30% 61.1°
2025-04-23 Wed 72 72 51 03:00–04:00 (good, 1.0 h) 87.3° 08:10 6.81 21% 58.9°
2025-04-24 Thu 74 91 68 02:00–04:45 (good, 2.75 h) 87.3° 08:05 6.76 12% 58.9°
2025-04-25 Fri 74 100 74 01:50–04:40 (good, 2.83 h) 87.3° 08:05 6.7 5% 61.1°
2025-04-26 Sat 76 44 33 02:00–04:40 (marginal, 2.67 h) 87.3° 08:00 6.64 1% 65.4°
2025-04-27 Sun 78 0 0 — 87.3° 07:55 6.58 0% 71.4°
2025-04-28 Mon 78 100 78 01:35–04:35 (good, 3.0 h) 87.3° 07:50 6.52 2% 78.5°
2025-04-29 Tue 79 100 79 01:35–04:35 (good, 3.0 h) 87.3° 07:45 6.47 7% 86.0°
2025-04-30 Wed 81 87 71 01:35–04:35 (good, 3.0 h) 87.3° 07:45 6.41 14% 93.7°
2025-05-01 Thu 81 28 22 03:00–04:30 (marginal, 1.5 h) 87.3° 07:40 6.35 23% 100.9°
2025-05-02 Fri 82 99 82 01:25–04:30 (good, 3.08 h) 87.3° 07:35 6.29 33% 107.4°
2025-05-03 Sat 81 100 81 01:25–04:25 (good, 3.0 h) 87.3° 07:30 6.23 43% 112.9°
2025-05-04 Sun 81 13 10 00:45–01:00 (marginal, 0.25 h) 87.3° 07:30 6.18 54% 117.2°
2025-05-05 Mon 83 76 63 04:00–04:25 (good, 0.42 h) 87.3° 07:25 6.12 64% 120.0°
2025-05-06 Tue 82 0 0 — 87.3° 07:20 6.06 73% 121.3°
2025-05-07 Wed 82 73 60 01:15–04:00 (good, 2.75 h) 87.3° 07:15 6.0 81% 121.1°
2025-05-08 Thu 76 74 56 01:10–04:00 (good, 2.83 h) 87.3° 07:10 5.95 88% 119.3°
2025-05-09 Fri 72 0 0 — 87.3° 07:10 5.89 93% 116.2°
2025-05-10 Sat 69 0 0 — 87.3° 07:05 5.84 97% 112.1°
2025-05-11 Sun 66 0 0 — 87.3° 07:00 5.78 99% 107.1°
2025-05-12 Mon 62 0 0 — 87.3° 06:55 5.73 100% 101.5°
2025-05-13 Tue 59 0 0 — 87.3° 06:50 5.67 98% 95.4°
2025-05-14 Wed 57 100 57 01:05–04:10 (good, 3.08 h) 87.3° 06:50 5.62 95% 89.2°
2025-05-15 Thu 55 0 0 — 87.3° 06:45 5.56 90% 82.8°
2025-05-16 Fri 58 0 0 — 87.3° 06:40 5.51 84% 76.7°
2025-05-17 Sat 68 18 12 00:00–01:00 (marginal, 1.0 h) 87.3° 06:35 5.46 76% 70.9°
2025-05-18 Sun 75 100 75 00:20–04:00 (good, 3.67 h) 87.3° 06:35 5.41 66% 65.8°
2025-05-19 Mon 83 95 79 00:30–04:00 (good, 3.5 h) 87.3° 06:30 5.36 56% 61.8°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-04-20&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.