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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: 09-01 (100), 09-02 (100), 09-03 (100), 09-04 (100), 09-05 (100) — by astronomy; check the weather when the night is within four days.
2026-08-25astronomy score per night — click a bar for that night2026-09-23
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-08-25 Tue 51 97 50 21:50–04:40 (marginal, 6.83 h) 71.1° 23:05 7.22 95% 44.3°
2026-08-26 Wed 45 93 42 21:45–04:20 (marginal, 6.58 h) 71.1° 23:05 7.27 98% 44.2°
2026-08-27 Thu 44 97 43 21:45–04:05 (marginal, 6.33 h) 71.1° 23:00 7.33 100% 46.8°
2026-08-28 Fri 48 94 45 21:45–03:55 (marginal, 6.17 h) 71.1° 22:55 7.39 99% 51.9°
2026-08-29 Sat 58 24 14 21:40–23:00 (marginal, 1.33 h) 71.1° 22:50 7.44 97% 59.0°
2026-08-30 Sun 71 97 69 21:40–00:25 (good, 2.75 h) 71.1° 22:45 7.5 92% 67.3°
2026-08-31 Mon 79 99 78 21:35–01:40 (good, 4.08 h) 71.1° 22:45 7.56 85% 76.6°
2026-09-01 Tue 100 91 91 21:35–02:45 (good, 5.17 h) 71.1° 22:40 7.61 76% 86.3°
2026-09-02 Wed 100 9 9 — 71.1° 22:35 7.67 66% 96.3°
2026-09-03 Thu 100 89 89 21:30–03:10 (good, 5.67 h) 71.1° 22:30 7.72 55% 106.2°
2026-09-04 Fri 100 96 96 21:30–03:30 (good, 6.0 h) 71.1° 22:25 7.78 43% 115.6°
2026-09-05 Sat 100 100 100 21:25–03:25 (good, 6.0 h) 71.1° 22:25 7.83 32% 124.1°
2026-09-06 Sun 100 99 99 21:25–03:25 (good, 6.0 h) 71.1° 22:20 7.89 22% 131.0°
2026-09-07 Mon 100 100 100 21:25–03:20 (good, 5.92 h) 71.1° 22:15 7.94 13% 135.2°
2026-09-08 Tue 100 100 100 21:20–03:20 (good, 6.0 h) 71.1° 22:10 8.0 6% 136.0°
2026-09-09 Wed 100 91 91 21:20–03:00 (good, 5.67 h) 71.1° 22:10 8.05 2% 133.2°
2026-09-10 Thu 100 99 99 21:15–03:10 (good, 5.92 h) 71.1° 22:05 8.11 0% 127.6°
2026-09-11 Fri 100 98 98 21:15–03:05 (good, 5.83 h) 71.1° 22:00 8.16 1% 120.1°
2026-09-12 Sat 100 0 0 — 71.1° 21:55 8.21 4% 111.7°
2026-09-13 Sun 100 84 84 21:10–02:40 (good, 5.5 h) 71.1° 21:50 8.27 9% 102.7°
2026-09-14 Mon 100 51 51 00:00–02:00 (good, 2.0 h) 71.1° 21:50 8.32 15% 93.7°
2026-09-15 Tue 100 63 63 22:00–00:00 (good, 2.0 h) 71.1° 21:45 8.37 23% 84.7°
2026-09-16 Wed 100 96 96 21:05–02:45 (good, 5.67 h) 71.1° 21:40 8.42 32% 76.1°
2026-09-17 Thu 100 100 100 21:05–02:40 (good, 5.58 h) 71.1° 21:35 8.48 41% 67.9°
2026-09-18 Fri 100 83 83 21:00–02:35 (good, 5.58 h) 71.1° 21:30 8.53 51% 60.4°
2026-09-19 Sat 94 92 87 21:00–02:00 (good, 5.0 h) 71.1° 21:30 8.58 60% 53.7°
2026-09-20 Sun 86 97 83 21:00–02:30 (good, 5.5 h) 71.1° 21:25 8.63 69% 48.4°
2026-09-21 Mon 64 0 0 — 71.1° 21:20 8.68 78% 44.9°
2026-09-22 Tue 47 3 2 — 71.1° 21:15 8.73 85% 43.9°
2026-09-23 Wed 41 86 35 20:50–02:25 (marginal, 5.58 h) 71.1° 21:15 8.78 92% 45.6°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-08-25&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.