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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: 06-22 (100), 06-23 (100), 06-24 (100), 06-25 (100), 06-26 (100) — by astronomy; check the weather when the night is within four days.
2025-06-22astronomy score per night — click a bar for that night2025-07-21
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-06-22 Sun 100 100 100 23:15–03:40 (good, 4.42 h) 71.1° 03:15 4.42 9% 100.4°
2025-06-23 Mon 100 100 100 23:15–03:40 (good, 4.42 h) 71.1° 03:15 4.43 3% 110.3°
2025-06-24 Tue 100 100 100 23:15–03:40 (good, 4.42 h) 71.1° 03:10 4.44 1% 119.4°
2025-06-25 Wed 100 100 100 23:15–03:40 (good, 4.42 h) 71.1° 03:05 4.45 0% 126.9°
2025-06-26 Thu 100 100 100 23:15–03:40 (good, 4.42 h) 71.1° 03:00 4.46 3% 132.1°
2025-06-27 Fri 100 78 78 23:15–03:40 (good, 4.42 h) 71.1° 03:00 4.47 8% 134.5°
2025-06-28 Sat 100 38 38 03:00–03:40 (good, 0.67 h) 71.1° 02:55 4.48 15% 133.7°
2025-06-29 Sun 100 100 100 23:10–03:40 (good, 4.5 h) 71.1° 02:50 4.5 23% 130.1°
2025-06-30 Mon 100 94 94 23:10–03:45 (good, 4.58 h) 71.1° 02:45 4.52 32% 124.7°
2025-07-01 Tue 100 88 88 00:00–03:45 (good, 3.75 h) 71.1° 02:40 4.54 42% 117.9°
2025-07-02 Wed 100 100 100 23:10–03:45 (good, 4.58 h) 71.1° 02:40 4.56 51% 110.4°
2025-07-03 Thu 100 100 100 23:10–03:45 (good, 4.58 h) 71.1° 02:35 4.59 61% 102.4°
2025-07-04 Fri 100 100 100 23:10–03:45 (good, 4.58 h) 71.1° 02:30 4.62 70% 94.2°
2025-07-05 Sat 100 100 100 23:10–03:50 (good, 4.67 h) 71.1° 02:25 4.64 78% 85.9°
2025-07-06 Sun 100 99 99 23:10–03:50 (good, 4.67 h) 71.1° 02:20 4.67 85% 77.6°
2025-07-07 Mon 100 99 99 23:15–03:50 (good, 4.58 h) 71.1° 02:20 4.7 91% 69.6°
2025-07-08 Tue 70 100 70 23:35–03:50 (good, 4.25 h) 71.1° 02:15 4.74 96% 61.9°
2025-07-09 Wed 57 99 56 01:55–03:50 (good, 1.92 h) 71.1° 02:10 4.77 99% 55.1°
2025-07-10 Thu 48 81 39 23:05–03:55 (marginal, 4.83 h) 71.1° 02:05 4.81 100% 49.7°
2025-07-11 Fri 45 40 18 02:00–03:55 (marginal, 1.92 h) 71.1° 02:00 4.85 99% 46.2°
2025-07-12 Sat 48 86 41 23:05–03:55 (marginal, 4.83 h) 71.1° 02:00 4.88 95% 45.5°
2025-07-13 Sun 57 46 26 00:00–01:00 (marginal, 1.0 h) 71.1° 01:55 4.92 90% 47.7°
2025-07-14 Mon 95 100 95 23:00–02:35 (good, 3.58 h) 71.1° 01:50 4.97 82% 52.6°
2025-07-15 Tue 98 90 88 23:00–03:15 (good, 4.25 h) 71.1° 01:45 5.01 73% 59.6°
2025-07-16 Wed 100 87 87 23:00–04:00 (good, 5.0 h) 71.1° 01:45 5.05 62% 68.1°
2025-07-17 Thu 100 50 50 00:00–03:00 (good, 3.0 h) 71.1° 01:40 5.1 51% 77.4°
2025-07-18 Fri 100 93 93 22:55–04:00 (good, 5.08 h) 71.1° 01:35 5.14 40% 87.3°
2025-07-19 Sat 100 100 100 22:55–04:05 (good, 5.17 h) 71.1° 01:30 5.19 29% 97.3°
2025-07-20 Sun 100 100 100 22:55–04:05 (good, 5.17 h) 71.1° 01:25 5.24 19% 107.1°
2025-07-21 Mon 100 100 100 22:50–04:10 (good, 5.33 h) 71.1° 01:25 5.28 11% 116.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-06-22&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.