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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), 12-27 (85), 12-26 (83), 12-25 (82) — by astronomy; check the weather when the night is within four days.
2025-11-30astronomy score per night — click a bar for that night2025-12-29
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-11-30 Sun 37 0 0 — 50.2° 08:10 11.32 78% 170.4°
2025-12-01 Mon 39 0 0 — 50.2° 08:05 11.34 86% 157.5°
2025-12-02 Tue 38 85 32 04:25–05:55 (good, 1.5 h) 50.2° 08:00 11.35 94% 143.0°
2025-12-03 Wed 35 0 0 — 50.2° 08:00 11.37 98% 128.0°
2025-12-04 Thu 32 0 0 — 50.2° 07:55 11.38 100% 112.9°
2025-12-05 Fri 25 0 0 — 50.2° 07:50 11.4 98% 97.8°
2025-12-06 Sat 20 0 0 — 50.2° 07:45 11.41 94% 82.9°
2025-12-07 Sun 17 0 0 — 50.2° 07:45 11.42 88% 68.4°
2025-12-08 Mon 15 0 0 — 50.2° 07:40 11.44 79% 54.4°
2025-12-09 Tue 15 0 0 — 50.2° 07:35 11.45 70% 40.9°
2025-12-10 Wed 18 63 11 03:45–05:00 (marginal, 1.25 h) 50.2° 07:30 11.46 60% 28.1°
2025-12-11 Thu 25 74 19 04:00–06:00 (marginal, 2.0 h) 50.2° 07:25 11.47 49% 16.0°
2025-12-12 Fri 32 0 0 — 50.2° 07:25 11.47 40% 7.1°
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°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-11-30&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.