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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 North America Nebula: 05-23 (100), 05-24 (100), 05-25 (100), 05-26 (100), 05-27 (100) — by astronomy; check the weather when the night is within four days.
2025-05-11astronomy score per night — click a bar for that night2025-06-09
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-05-11 Sun 66 0 0 — 87.3° 07:00 5.78 99% 107.1°
2025-05-12 Mon 62 0 0 — 87.3° 06:55 5.73 100% 101.5°
2025-05-13 Tue 59 0 0 — 87.2° 06:50 5.67 98% 95.5°
2025-05-14 Wed 57 100 57 01:00–04:10 (good, 3.17 h) 87.2° 06:50 5.62 95% 89.2°
2025-05-15 Thu 55 0 0 — 87.3° 06:45 5.56 90% 82.9°
2025-05-16 Fri 58 0 0 — 87.3° 06:40 5.51 84% 76.7°
2025-05-17 Sat 69 18 13 00:00–01:00 (marginal, 1.0 h) 87.3° 06:35 5.46 76% 71.0°
2025-05-18 Sun 76 100 76 00:20–04:00 (good, 3.67 h) 87.2° 06:30 5.41 66% 65.9°
2025-05-19 Mon 83 95 79 00:30–04:00 (good, 3.5 h) 87.3° 06:30 5.36 56% 61.9°
2025-05-20 Tue 90 31 28 03:00–04:00 (good, 1.0 h) 87.3° 06:25 5.31 45% 59.3°
2025-05-21 Wed 96 74 71 00:15–02:00 (good, 1.75 h) 87.3° 06:20 5.26 34% 58.6°
2025-05-22 Thu 99 96 95 00:05–03:55 (good, 3.83 h) 87.2° 06:15 5.21 24% 59.9°
2025-05-23 Fri 100 6 6 — 87.2° 06:15 5.16 15% 63.3°
2025-05-24 Sat 100 0 0 — 87.3° 06:10 5.12 7% 68.6°
2025-05-25 Sun 100 0 0 — 87.3° 06:05 5.07 2% 75.2°
2025-05-26 Mon 100 76 76 01:25–03:50 (good, 2.42 h) 87.3° 06:00 5.03 0% 82.6°
2025-05-27 Tue 100 99 99 23:40–03:50 (good, 4.17 h) 87.2° 05:55 4.98 1% 90.4°
2025-05-28 Wed 100 91 91 23:40–03:50 (good, 4.17 h) 87.2° 05:55 4.94 5% 98.0°
2025-05-29 Thu 100 15 15 23:30–01:00 (marginal, 1.5 h) 87.3° 05:50 4.9 11% 105.1°
2025-05-30 Fri 100 20 20 02:00–03:45 (marginal, 1.75 h) 87.3° 05:45 4.86 19% 111.2°
2025-05-31 Sat 100 85 85 23:45–03:45 (good, 4.0 h) 87.3° 05:40 4.82 28% 116.1°
2025-06-01 Sun 100 22 22 23:55–00:00 (good, 0.08 h) 87.2° 05:35 4.79 38% 119.5°
2025-06-02 Mon 100 99 99 23:30–03:45 (good, 4.25 h) 87.2° 05:35 4.75 48% 121.3°
2025-06-03 Tue 100 100 100 23:20–03:45 (good, 4.42 h) 87.3° 05:30 4.72 58% 121.5°
2025-06-04 Wed 100 100 100 23:20–03:40 (good, 4.33 h) 87.3° 05:25 4.69 67% 120.1°
2025-06-05 Thu 100 17 17 03:00–03:40 (good, 0.67 h) 87.2° 05:20 4.65 76% 117.3°
2025-06-06 Fri 100 100 100 23:20–03:40 (good, 4.33 h) 87.2° 05:20 4.63 83% 113.4°
2025-06-07 Sat 100 100 100 23:20–03:40 (good, 4.33 h) 87.3° 05:15 4.6 90% 108.6°
2025-06-08 Sun 86 99 86 23:20–03:40 (good, 4.33 h) 87.3° 05:10 4.57 95% 103.1°
2025-06-09 Mon 82 94 77 00:00–03:40 (good, 3.67 h) 87.3° 05:05 4.55 98% 97.1°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-05-11&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.