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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: 11-09 (89), 11-10 (89), 11-11 (89), 11-08 (88), 11-12 (88) — by astronomy; check the weather when the night is within four days.
2025-10-31astronomy score per night — click a bar for that night2025-11-29
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-10-31 Fri 40 1 1 — 71.1° 17:40 10.47 73% 49.6°
2025-11-01 Sat 36 92 33 18:50–22:55 (marginal, 4.08 h) 71.1° 17:40 10.51 82% 55.7°
2025-11-02 Sun 35 74 26 18:50–19:00 (good, 0.17 h) 71.1° 17:35 10.55 90% 63.8°
2025-11-03 Mon 38 10 4 18:50–19:00 (marginal, 0.17 h) 71.1° 17:30 10.58 96% 73.3°
2025-11-04 Tue 44 0 0 — 71.1° 17:25 10.62 99% 83.7°
2025-11-05 Wed 54 0 0 — 71.1° 17:20 10.65 100% 94.5°
2025-11-06 Thu 65 0 0 — 71.1° 17:20 10.69 97% 105.1°
2025-11-07 Fri 76 0 0 — 71.1° 17:15 10.72 92% 114.9°
2025-11-08 Sat 88 0 0 — 71.1° 17:10 10.75 84% 123.5°
2025-11-09 Sun 89 7 6 — 71.1° 17:05 10.78 74% 130.1°
2025-11-10 Mon 89 0 0 — 71.1° 17:05 10.82 64% 134.0°
2025-11-11 Tue 89 89 79 18:40–22:05 (good, 3.42 h) 71.1° 17:00 10.85 53% 134.8°
2025-11-12 Wed 88 45 40 21:00–22:00 (good, 1.0 h) 71.1° 16:55 10.88 43% 132.6°
2025-11-13 Thu 86 99 85 18:40–21:55 (good, 3.25 h) 71.1° 16:50 10.91 33% 128.1°
2025-11-14 Fri 85 100 85 18:40–21:55 (good, 3.25 h) 71.1° 16:45 10.94 24% 121.9°
2025-11-15 Sat 83 92 77 18:40–21:50 (good, 3.17 h) 71.1° 16:45 10.97 16% 114.7°
2025-11-16 Sun 82 55 45 18:40–19:00 (good, 0.33 h) 71.1° 16:40 10.99 10% 106.9°
2025-11-17 Mon 80 0 0 — 71.1° 16:35 11.02 5% 98.7°
2025-11-18 Tue 78 0 0 — 71.1° 16:30 11.05 2% 90.4°
2025-11-19 Wed 77 4 3 — 71.1° 16:25 11.08 0% 82.0°
2025-11-20 Thu 75 12 9 — 71.1° 16:25 11.1 0% 73.9°
2025-11-21 Fri 73 1 0 — 71.1° 16:20 11.13 3% 66.1°
2025-11-22 Sat 72 48 35 20:00–21:00 (good, 1.0 h) 71.1° 16:15 11.15 6% 58.9°
2025-11-23 Sun 68 97 66 18:35–21:20 (good, 2.75 h) 71.1° 16:10 11.17 12% 52.7°
2025-11-24 Mon 61 97 59 18:35–21:10 (good, 2.58 h) 71.1° 16:10 11.2 18% 48.0°
2025-11-25 Tue 52 0 0 — 71.1° 16:05 11.22 27% 45.4°
2025-11-26 Wed 45 5 2 — 71.1° 16:00 11.24 36% 45.3°
2025-11-27 Thu 37 0 0 — 71.1° 15:55 11.26 46% 47.9°
2025-11-28 Fri 31 0 0 — 71.1° 15:50 11.28 57% 53.1°
2025-11-29 Sat 26 0 0 — 71.1° 15:50 11.3 67% 60.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-10-31&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.