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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: 01-05 (45), 01-06 (44), 01-07 (43), 01-08 (42), 01-09 (41) — by astronomy; check the weather when the night is within four days.
2025-12-27astronomy score per night — click a bar for that night2026-01-25
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-12-27 Sat 35 100 35 18:40–20:45 (good, 2.08 h) 87.3° 14:55 11.49 51% 59.7°
2025-12-28 Sun 29 61 18 19:00–21:20 (marginal, 2.33 h) 87.2° 14:50 11.48 62% 63.6°
2025-12-29 Mon 25 100 25 18:40–21:30 (marginal, 2.83 h) 87.2° 14:50 11.48 73% 69.2°
2025-12-30 Tue 24 53 13 18:40–20:00 (marginal, 1.33 h) 87.3° 14:45 11.47 83% 76.1°
2025-12-31 Wed 24 60 14 18:45–20:00 (marginal, 1.25 h) 87.3° 14:40 11.46 91% 83.7°
2026-01-01 Thu 27 100 27 18:45–19:25 (good, 0.67 h) 87.3° 14:35 11.45 97% 91.8°
2026-01-02 Fri 31 92 29 18:45–19:40 (good, 0.92 h) 87.2° 14:30 11.44 100% 99.8°
2026-01-03 Sat 36 0 0 — 87.2° 14:30 11.43 100% 107.2°
2026-01-04 Sun 39 0 0 — 87.3° 14:25 11.42 97% 113.6°
2026-01-05 Mon 45 0 0 — 87.3° 14:20 11.4 92% 118.5°
2026-01-06 Tue 44 0 0 — 87.2° 14:15 11.39 84% 121.6°
2026-01-07 Wed 43 0 0 — 87.2° 14:10 11.37 76% 122.8°
2026-01-08 Thu 42 13 5 20:00–20:05 (marginal, 0.08 h) 87.2° 14:10 11.36 67% 122.0°
2026-01-09 Fri 41 39 16 18:50–19:00 (good, 0.17 h) 87.3° 14:05 11.34 57% 119.6°
2026-01-10 Sat 38 0 0 — 87.3° 14:00 11.32 47% 115.8°
2026-01-11 Sun 37 0 0 — 87.2° 13:55 11.31 38% 111.1°
2026-01-12 Mon 35 88 31 19:00–20:15 (good, 1.25 h) 87.2° 13:55 11.29 29% 105.6°
2026-01-13 Tue 34 0 0 — 87.3° 13:50 11.27 21% 99.6°
2026-01-14 Wed 32 98 31 18:55–20:05 (good, 1.17 h) 87.3° 13:45 11.25 14% 93.3°
2026-01-15 Thu 30 100 30 18:55–20:00 (good, 1.08 h) 87.3° 13:40 11.23 8% 86.9°
2026-01-16 Fri 29 0 0 — 87.2° 13:35 11.2 4% 80.4°
2026-01-17 Sat 27 85 23 19:00–19:40 (good, 0.67 h) 87.2° 13:35 11.18 1% 74.2°
2026-01-18 Sun 26 0 0 — 87.3° 13:30 11.16 0% 68.5°
2026-01-19 Mon 25 96 24 19:00–19:45 (good, 0.75 h) 87.3° 13:25 11.13 1% 63.6°
2026-01-20 Tue 23 91 21 19:00–19:40 (good, 0.67 h) 87.2° 13:20 11.11 5% 59.8°
2026-01-21 Wed 21 0 0 — 87.2° 13:15 11.08 10% 57.6°
2026-01-22 Thu 18 1 0 — 87.2° 13:15 11.06 17% 57.2°
2026-01-23 Fri 15 84 13 19:05–19:15 (good, 0.17 h) 87.3° 13:10 11.03 26% 58.9°
2026-01-24 Sat 12 0 0 — 87.3° 13:05 11.0 36% 62.4°
2026-01-25 Sun 10 0 0 — 87.2° 13:00 10.97 47% 67.5°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-12-27&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.