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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 Triangulum Pinwheel: 12-13 (100), 12-14 (100), 12-15 (100), 12-16 (100), 12-17 (100) — by astronomy; check the weather when the night is within four days.
2025-12-13astronomy score per night — click a bar for that night2026-01-11
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-12-13 Sat 100 20 20 18:35–19:00 (good, 0.42 h) 79.1° 20:25 11.48 30% 155.8°
2025-12-14 Sun 100 60 60 18:35–22:00 (good, 3.42 h) 79.1° 20:20 11.49 22% 163.1°
2025-12-15 Mon 100 100 100 18:35–01:50 (good, 7.25 h) 79.1° 20:20 11.49 15% 163.8°
2025-12-16 Tue 100 100 100 18:35–01:45 (good, 7.17 h) 79.1° 20:15 11.5 9% 157.3°
2025-12-17 Wed 100 67 67 18:35–23:00 (good, 4.42 h) 79.1° 20:10 11.5 4% 147.8°
2025-12-18 Thu 100 0 0 — 79.1° 20:05 11.5 1% 137.2°
2025-12-19 Fri 100 95 95 18:35–01:20 (good, 6.75 h) 79.1° 20:00 11.51 0% 126.0°
2025-12-20 Sat 100 10 10 18:35–19:00 (good, 0.42 h) 79.1° 20:00 11.51 1% 114.5°
2025-12-21 Sun 100 0 0 — 79.1° 19:55 11.51 3% 102.8°
2025-12-22 Mon 100 18 18 18:35–20:00 (good, 1.42 h) 79.1° 19:50 11.51 8% 90.9°
2025-12-23 Tue 100 2 2 — 79.1° 19:45 11.51 14% 78.9°
2025-12-24 Wed 100 0 0 — 79.1° 19:40 11.5 21% 66.7°
2025-12-25 Thu 97 0 0 — 79.1° 19:40 11.5 30% 54.3°
2025-12-26 Fri 88 35 31 18:40–20:00 (marginal, 1.33 h) 79.1° 19:35 11.5 41% 42.0°
2025-12-27 Sat 74 100 74 18:40–01:05 (good, 6.42 h) 79.1° 19:30 11.49 51% 29.9°
2025-12-28 Sun 57 64 36 19:00–22:00 (marginal, 3.0 h) 79.1° 19:25 11.48 62% 19.5°
2025-12-29 Mon 36 100 36 18:40–01:10 (marginal, 6.5 h) 79.1° 19:25 11.48 73% 15.5°
2025-12-30 Tue 24 24 6 18:40–20:00 (marginal, 1.33 h) 79.1° 19:20 11.47 83% 22.5°
2025-12-31 Wed 20 41 8 18:45–19:00 (marginal, 0.25 h) 79.1° 19:15 11.46 91% 34.7°
2026-01-01 Thu 29 100 29 18:45–00:15 (marginal, 5.5 h) 79.1° 19:10 11.45 97% 48.4°
2026-01-02 Fri 44 83 36 18:45–23:00 (marginal, 4.25 h) 79.1° 19:05 11.44 100% 62.6°
2026-01-03 Sat 65 0 0 — 79.1° 19:05 11.43 100% 76.8°
2026-01-04 Sun 81 0 0 — 79.1° 19:00 11.42 97% 90.9°
2026-01-05 Mon 100 0 0 — 79.1° 18:55 11.4 92% 104.6°
2026-01-06 Tue 100 0 0 — 79.1° 18:50 11.39 84% 117.8°
2026-01-07 Wed 100 0 0 — 79.1° 18:45 11.37 76% 130.4°
2026-01-08 Thu 100 41 41 23:00–00:05 (good, 1.08 h) 79.1° 18:45 11.36 67% 142.2°
2026-01-09 Fri 100 52 52 21:00–23:00 (good, 2.0 h) 79.1° 18:40 11.34 57% 153.1°
2026-01-10 Sat 100 33 33 21:00–22:00 (good, 1.0 h) 79.1° 18:35 11.32 47% 161.7°
2026-01-11 Sun 100 0 0 — 79.1° 18:30 11.31 38% 164.7°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-12-13&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.