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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 3C 273: 12-29 (87), 12-28 (86), 12-30 (86), 12-27 (85), 12-26 (83) — 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 41 11 5 06:00–06:05 (marginal, 0.08 h) 50.2° 07:20 11.48 30% 12.0°
2025-12-14 Sun 49 100 49 03:35–06:05 (good, 2.5 h) 50.2° 07:15 11.49 22% 22.9°
2025-12-15 Mon 58 100 58 03:25–06:05 (good, 2.67 h) 50.2° 07:10 11.49 15% 34.4°
2025-12-16 Tue 64 14 9 02:55–03:00 (marginal, 0.08 h) 50.2° 07:05 11.5 9% 46.0°
2025-12-17 Wed 67 52 35 03:15–05:00 (good, 1.75 h) 50.2° 07:05 11.5 4% 57.7°
2025-12-18 Thu 69 17 12 05:00–06:00 (marginal, 1.0 h) 50.2° 07:00 11.5 1% 69.4°
2025-12-19 Fri 71 24 17 03:20–04:00 (marginal, 0.67 h) 50.2° 06:55 11.51 0% 81.3°
2025-12-20 Sat 72 0 0 — 50.2° 06:50 11.51 1% 93.3°
2025-12-21 Sun 74 0 0 — 50.2° 06:45 11.51 3% 105.4°
2025-12-22 Mon 76 0 0 — 50.2° 06:45 11.51 8% 117.6°
2025-12-23 Tue 78 0 0 — 50.2° 06:40 11.51 14% 130.0°
2025-12-24 Wed 79 0 0 — 50.2° 06:35 11.5 21% 142.5°
2025-12-25 Thu 82 4 3 — 50.2° 06:30 11.5 30% 155.1°
2025-12-26 Fri 83 13 11 04:55–05:00 (marginal, 0.08 h) 50.2° 06:30 11.5 41% 167.2°
2025-12-27 Sat 85 100 85 02:35–06:10 (good, 3.58 h) 50.2° 06:25 11.49 51% 172.6°
2025-12-28 Sun 86 99 85 02:35–06:10 (good, 3.58 h) 50.2° 06:20 11.48 62% 162.0°
2025-12-29 Mon 87 100 87 02:35–06:10 (good, 3.58 h) 50.2° 06:15 11.48 73% 148.4°
2025-12-30 Tue 86 37 32 05:00–06:10 (good, 1.17 h) 50.2° 06:10 11.47 83% 134.1°
2025-12-31 Wed 83 35 29 02:20–04:00 (marginal, 1.67 h) 50.2° 06:10 11.46 91% 119.4°
2026-01-01 Thu 64 88 56 02:40–05:00 (good, 2.33 h) 50.2° 06:05 11.45 97% 104.6°
2026-01-02 Fri 50 14 7 02:15–03:00 (marginal, 0.75 h) 50.2° 06:00 11.44 100% 89.7°
2026-01-03 Sat 37 10 4 06:00–06:10 (marginal, 0.17 h) 50.2° 05:55 11.43 100% 75.0°
2026-01-04 Sun 27 0 0 — 50.2° 05:50 11.42 97% 60.5°
2026-01-05 Mon 20 9 2 — 50.2° 05:50 11.4 92% 46.5°
2026-01-06 Tue 18 7 1 — 50.2° 05:45 11.39 84% 33.0°
2026-01-07 Wed 23 0 0 — 50.2° 05:40 11.37 76% 20.2°
2026-01-08 Thu 32 99 32 01:35–06:10 (marginal, 4.58 h) 50.2° 05:35 11.36 67% 9.3°
2026-01-09 Fri 43 12 5 — 50.2° 05:35 11.34 57% 9.4°
2026-01-10 Sat 55 19 10 02:00–03:00 (marginal, 1.0 h) 50.2° 05:30 11.32 47% 19.7°
2026-01-11 Sun 77 0 0 — 50.2° 05:25 11.31 38% 31.2°

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.