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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 HD 189733: 12-07 (44), 12-08 (44), 12-09 (42), 12-10 (41), 12-05 (40) — by astronomy; check the weather when the night is within four days.
2025-12-01astronomy score per night — click a bar for that night2025-12-30
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-12-01 Mon 24 90 22 18:35–21:05 (marginal, 2.5 h) 71.1° 15:40 11.34 86% 78.9°
2025-12-02 Tue 26 0 0 — 71.1° 15:35 11.35 94% 89.4°
2025-12-03 Wed 30 22 7 18:35–19:00 (marginal, 0.42 h) 71.1° 15:30 11.37 98% 100.1°
2025-12-04 Thu 35 0 0 — 71.1° 15:30 11.38 100% 110.5°
2025-12-05 Fri 40 0 0 — 71.1° 15:25 11.4 98% 120.0°
2025-12-06 Sat 40 0 0 — 71.1° 15:20 11.41 94% 127.8°
2025-12-07 Sun 44 9 4 — 71.1° 15:15 11.42 88% 133.0°
2025-12-08 Mon 44 55 24 19:00–19:55 (good, 0.92 h) 71.1° 15:15 11.44 79% 135.1°
2025-12-09 Tue 42 1 0 — 71.1° 15:10 11.45 70% 133.8°
2025-12-10 Wed 41 6 3 — 71.1° 15:05 11.46 60% 129.8°
2025-12-11 Thu 40 98 39 18:35–20:00 (good, 1.42 h) 71.1° 15:00 11.47 49% 123.9°
2025-12-12 Fri 38 99 37 18:35–20:00 (good, 1.42 h) 71.1° 14:55 11.47 40% 116.8°
2025-12-13 Sat 36 52 19 18:35–20:00 (marginal, 1.42 h) 71.1° 14:55 11.48 30% 109.0°
2025-12-14 Sun 35 100 35 18:35–19:55 (good, 1.33 h) 71.1° 14:50 11.49 22% 100.9°
2025-12-15 Mon 34 100 34 18:35–19:50 (good, 1.25 h) 71.1° 14:45 11.49 15% 92.5°
2025-12-16 Tue 32 100 32 18:35–19:45 (good, 1.17 h) 71.1° 14:40 11.5 9% 84.2°
2025-12-17 Wed 31 95 29 18:35–19:45 (good, 1.17 h) 71.1° 14:35 11.5 4% 75.9°
2025-12-18 Thu 29 0 0 — 71.1° 14:35 11.5 1% 68.0°
2025-12-19 Fri 28 94 26 18:35–19:30 (good, 0.92 h) 71.1° 14:30 11.51 0% 60.6°
2025-12-20 Sat 27 47 13 18:35–19:00 (good, 0.42 h) 71.1° 14:25 11.51 1% 54.0°
2025-12-21 Sun 25 2 1 — 71.1° 14:20 11.51 3% 48.8°
2025-12-22 Mon 22 74 16 18:35–19:00 (good, 0.42 h) 71.1° 14:20 11.51 8% 45.5°
2025-12-23 Tue 18 10 2 — 71.1° 14:15 11.51 14% 44.8°
2025-12-24 Wed 16 0 0 — 71.1° 14:10 11.5 21% 46.8°
2025-12-25 Thu 14 0 0 — 71.1° 14:05 11.5 30% 51.4°
2025-12-26 Fri 11 79 9 18:40–19:25 (marginal, 0.75 h) 71.1° 14:00 11.5 41% 58.0°
2025-12-27 Sat 9 100 9 18:05–19:30 (marginal, 1.42 h) 71.1° 14:00 11.49 51% 66.1°
2025-12-28 Sun 7 19 1 — 71.1° 13:55 11.48 62% 75.4°
2025-12-29 Mon 6 100 6 18:40–19:20 (marginal, 0.67 h) 71.1° 13:50 11.48 73% 85.3°
2025-12-30 Tue 6 94 6 18:40–19:10 (marginal, 0.5 h) 71.1° 13:45 11.47 83% 95.7°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-12-01&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.