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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: 05-23 (100), 05-22 (97), 05-21 (92), 05-20 (83), 05-05 (78) — by astronomy; check the weather when the night is within four days.
2025-04-24astronomy score per night — click a bar for that night2025-05-23
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
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°
2025-04-29 Tue 73 100 73 01:50–04:35 (good, 2.75 h) 71.1° 06:50 6.47 7% 108.9°
2025-04-30 Wed 75 87 65 02:05–04:35 (good, 2.5 h) 71.1° 06:45 6.41 14% 117.9°
2025-05-01 Thu 75 30 23 03:00–04:30 (marginal, 1.5 h) 71.1° 06:40 6.35 23% 125.5°
2025-05-02 Fri 76 99 76 01:40–04:30 (good, 2.83 h) 71.1° 06:40 6.29 33% 130.9°
2025-05-03 Sat 76 100 76 01:35–04:25 (good, 2.83 h) 71.1° 06:35 6.23 43% 133.8°
2025-05-04 Sun 77 9 7 05:00–05:05 (marginal, 0.08 h) 71.1° 06:30 6.18 54% 133.8°
2025-05-05 Mon 78 74 58 04:00–04:25 (good, 0.42 h) 71.1° 06:25 6.12 64% 131.2°
2025-05-06 Tue 76 0 0 — 71.1° 06:20 6.06 73% 126.5°
2025-05-07 Wed 76 71 54 01:30–04:00 (good, 2.5 h) 71.1° 06:20 6.0 81% 120.4°
2025-05-08 Thu 68 72 49 01:25–04:00 (good, 2.58 h) 71.1° 06:15 5.95 88% 113.3°
2025-05-09 Fri 62 0 0 — 71.1° 06:10 5.89 93% 105.6°
2025-05-10 Sat 56 0 0 — 71.1° 06:05 5.84 97% 97.6°
2025-05-11 Sun 51 0 0 — 71.1° 06:00 5.78 99% 89.4°
2025-05-12 Mon 45 0 0 — 71.1° 06:00 5.73 100% 81.1°
2025-05-13 Tue 42 0 0 — 71.1° 05:55 5.67 98% 73.1°
2025-05-14 Wed 40 100 40 02:55–04:10 (good, 1.25 h) 71.1° 05:50 5.62 95% 65.3°
2025-05-15 Thu 38 0 0 — 71.1° 05:45 5.56 90% 58.3°
2025-05-16 Fri 41 0 0 — 71.1° 05:45 5.51 84% 52.3°
2025-05-17 Sat 58 16 9 00:15–01:00 (marginal, 0.75 h) 71.1° 05:40 5.46 76% 47.9°
2025-05-18 Sun 67 100 67 00:35–04:00 (good, 3.42 h) 71.1° 05:35 5.41 66% 45.9°
2025-05-19 Mon 76 96 73 00:40–04:00 (good, 3.33 h) 71.1° 05:30 5.36 56% 46.6°
2025-05-20 Tue 83 28 24 03:00–04:00 (good, 1.0 h) 71.1° 05:25 5.31 45% 50.1°
2025-05-21 Wed 92 73 68 00:30–02:00 (good, 1.5 h) 71.1° 05:25 5.26 34% 56.2°
2025-05-22 Thu 97 96 93 00:20–03:55 (good, 3.58 h) 71.1° 05:20 5.21 24% 64.1°
2025-05-23 Fri 100 5 5 — 71.1° 05:15 5.16 15% 73.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-04-24&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.