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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: 10-10 (100), 10-11 (100), 10-12 (100), 10-13 (100), 10-14 (100) — by astronomy; check the weather when the night is within four days.
2025-09-29astronomy score per night — click a bar for that night2025-10-28
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-09-29 Mon 97 0 0 — 71.1° 20:50 9.09 49% 55.7°
2025-09-30 Tue 89 32 29 00:00–01:30 (good, 1.5 h) 71.1° 20:45 9.14 59% 50.2°
2025-10-01 Wed 75 0 0 — 71.1° 20:40 9.19 69% 46.5°
2025-10-02 Thu 51 0 0 — 71.1° 20:35 9.24 78% 45.4°
2025-10-03 Fri 43 0 0 — 71.1° 20:30 9.29 86% 47.3°
2025-10-04 Sat 39 91 35 20:30–01:40 (marginal, 5.17 h) 71.1° 20:30 9.33 93% 52.0°
2025-10-05 Sun 40 72 29 20:30–23:00 (marginal, 2.5 h) 71.1° 20:25 9.38 98% 59.2°
2025-10-06 Mon 47 0 0 — 71.1° 20:20 9.43 100% 68.1°
2025-10-07 Tue 58 0 0 — 71.1° 20:15 9.47 99% 78.1°
2025-10-08 Wed 71 0 0 — 71.1° 20:15 9.52 95% 88.6°
2025-10-09 Thu 85 94 80 20:25–00:50 (good, 4.42 h) 71.1° 20:10 9.57 89% 99.1°
2025-10-10 Fri 100 93 93 20:20–00:55 (good, 4.58 h) 71.1° 20:05 9.61 80% 109.1°
2025-10-11 Sat 100 51 51 20:20–22:00 (good, 1.67 h) 71.1° 20:00 9.66 70% 118.2°
2025-10-12 Sun 100 26 26 00:00–01:30 (marginal, 1.5 h) 71.1° 19:55 9.7 59% 125.8°
2025-10-13 Mon 100 8 8 — 71.1° 19:55 9.74 48% 131.4°
2025-10-14 Tue 100 0 0 — 71.1° 19:50 9.79 38% 134.3°
2025-10-15 Wed 100 15 15 23:00–00:00 (good, 1.0 h) 71.1° 19:45 9.83 28% 134.3°
2025-10-16 Thu 100 0 0 — 71.1° 19:40 9.87 19% 131.6°
2025-10-17 Fri 100 0 0 — 71.1° 19:35 9.92 12% 126.6°
2025-10-18 Sat 100 0 0 — 71.1° 19:35 9.96 6% 120.2°
2025-10-19 Sun 100 0 0 — 71.1° 19:30 10.0 2% 112.8°
2025-10-20 Mon 100 40 40 20:05–21:00 (good, 0.92 h) 71.1° 19:25 10.04 0% 104.8°
2025-10-21 Tue 100 22 22 23:00–00:00 (marginal, 1.0 h) 71.1° 19:20 10.08 0% 96.6°
2025-10-22 Wed 100 63 63 20:05–22:00 (good, 1.92 h) 71.1° 19:15 10.13 2% 88.2°
2025-10-23 Thu 100 40 40 20:05–21:25 (good, 1.33 h) 71.1° 19:15 10.17 5% 80.0°
2025-10-24 Fri 100 56 56 20:00–21:00 (good, 1.0 h) 71.1° 19:10 10.21 10% 71.9°
2025-10-25 Sat 100 63 63 20:00–22:00 (good, 2.0 h) 71.1° 19:05 10.25 17% 64.3°
2025-10-26 Sun 99 0 0 — 71.1° 18:00 10.29 24% 57.4°
2025-10-27 Mon 91 93 85 19:00–23:05 (good, 4.08 h) 71.1° 18:00 10.32 33% 51.6°
2025-10-28 Tue 76 98 75 18:55–23:00 (good, 4.08 h) 71.1° 17:55 10.36 42% 47.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-09-29&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.