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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: 04-27 (72), 04-28 (72), 04-26 (70), 04-24 (69), 04-25 (68) — by astronomy; check the weather when the night is within four days.
2025-03-30astronomy score per night — click a bar for that night2025-04-28
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-03-30 Sun 45 0 0 — 71.1° 08:45 8.18 3% 82.5°
2025-03-31 Mon 46 0 0 — 71.1° 08:45 8.12 9% 93.0°
2025-04-01 Tue 47 0 0 — 71.1° 08:40 8.07 17% 103.1°
2025-04-02 Wed 47 0 0 — 71.1° 08:35 8.01 27% 112.5°
2025-04-03 Thu 48 0 0 — 71.1° 08:30 7.96 37% 120.8°
2025-04-04 Fri 50 0 0 — 71.1° 08:30 7.9 48% 127.4°
2025-04-05 Sat 49 78 38 04:00–05:20 (good, 1.33 h) 71.1° 08:25 7.85 59% 131.9°
2025-04-06 Sun 50 0 0 — 71.1° 08:20 7.79 69% 133.9°
2025-04-07 Mon 49 2 1 — 71.1° 08:15 7.74 78% 133.2°
2025-04-08 Tue 45 87 39 04:05–05:15 (good, 1.17 h) 71.1° 08:10 7.68 85% 130.0°
2025-04-09 Wed 46 93 43 03:35–05:15 (good, 1.67 h) 71.1° 08:10 7.62 92% 125.0°
2025-04-10 Thu 44 38 17 05:00–05:10 (good, 0.17 h) 71.1° 08:05 7.57 96% 118.6°
2025-04-11 Fri 41 3 1 — 71.1° 08:00 7.51 99% 111.4°
2025-04-12 Sat 37 0 0 — 71.1° 07:55 7.45 100% 103.6°
2025-04-13 Sun 34 0 0 — 71.1° 07:50 7.39 99% 95.5°
2025-04-14 Mon 32 7 2 — 71.1° 07:50 7.34 97% 87.3°
2025-04-15 Tue 31 79 24 02:35–05:00 (marginal, 2.42 h) 71.1° 07:45 7.28 92% 79.1°
2025-04-16 Wed 30 96 29 04:05–05:00 (good, 0.92 h) 71.1° 07:40 7.22 87% 71.2°
2025-04-17 Thu 31 0 0 — 71.1° 07:35 7.16 79% 63.6°
2025-04-18 Fri 33 0 0 — 71.1° 07:35 7.11 71% 56.8°
2025-04-19 Sat 38 37 14 02:40–02:45 (good, 0.08 h) 71.1° 07:30 7.05 62% 51.2°
2025-04-20 Sun 49 84 41 03:00–04:50 (good, 1.83 h) 71.1° 07:25 6.99 52% 47.4°
2025-04-21 Mon 56 79 45 03:00–04:00 (good, 1.0 h) 71.1° 07:20 6.93 41% 46.0°
2025-04-22 Tue 61 59 36 04:00–04:50 (good, 0.83 h) 71.1° 07:15 6.87 30% 47.5°
2025-04-23 Wed 66 74 49 03:00–04:00 (good, 1.0 h) 71.1° 07:15 6.81 21% 52.0°
2025-04-24 Thu 69 92 63 02:15–04:45 (good, 2.5 h) 71.1° 07:10 6.76 12% 59.0°
2025-04-25 Fri 68 100 68 02:05–04:40 (good, 2.58 h) 71.1° 07:05 6.7 5% 67.8°
2025-04-26 Sat 70 47 33 02:00–04:40 (marginal, 2.67 h) 71.1° 07:00 6.64 1% 77.7°
2025-04-27 Sun 72 0 0 — 71.1° 06:55 6.58 0% 88.2°
2025-04-28 Mon 72 100 72 01:50–04:35 (good, 2.75 h) 71.1° 06:55 6.52 2% 98.8°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-03-30&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.