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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 Great Orion Nebula: 10-28 (89), 10-29 (89), 10-30 (89), 10-31 (89), 11-01 (89) — by astronomy; check the weather when the night is within four days.
2025-10-28astronomy score per night — click a bar for that night2025-11-26
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-10-28 Tue 89 100 89 00:15–05:20 (good, 5.08 h) 42.9° 03:25 10.36 42% 133.9°
2025-10-29 Wed 89 100 89 00:10–05:20 (good, 5.17 h) 42.9° 03:25 10.4 52% 125.2°
2025-10-30 Thu 89 31 28 00:10–02:00 (good, 1.83 h) 42.9° 03:20 10.44 63% 115.3°
2025-10-31 Fri 89 65 58 00:15–02:00 (good, 1.75 h) 42.9° 03:15 10.47 73% 104.6°
2025-11-01 Sat 89 99 88 00:25–05:25 (good, 5.0 h) 42.9° 03:10 10.51 82% 93.1°
2025-11-02 Sun 87 95 83 01:35–05:25 (good, 3.83 h) 42.9° 03:05 10.55 90% 81.2°
2025-11-03 Mon 71 0 0 — 42.9° 03:05 10.58 96% 69.1°
2025-11-04 Tue 35 0 0 — 42.9° 03:00 10.62 99% 57.4°
2025-11-05 Wed 22 0 0 — 42.9° 02:55 10.65 100% 46.6°
2025-11-06 Thu 15 0 0 — 42.9° 02:50 10.69 97% 38.2°
2025-11-07 Fri 13 0 0 — 42.9° 02:50 10.72 92% 33.9°
2025-11-08 Sat 20 0 0 — 42.9° 02:45 10.75 84% 35.2°
2025-11-09 Sun 34 0 0 — 42.9° 02:40 10.78 74% 41.2°
2025-11-10 Mon 53 0 0 — 42.9° 02:35 10.82 64% 49.8°
2025-11-11 Tue 68 100 68 23:40–04:30 (good, 4.83 h) 42.9° 02:30 10.85 53% 59.7°
2025-11-12 Wed 83 99 83 23:15–05:20 (good, 6.08 h) 42.9° 02:30 10.88 43% 69.9°
2025-11-13 Thu 87 87 76 23:10–04:00 (good, 4.83 h) 42.9° 02:25 10.91 33% 80.3°
2025-11-14 Fri 89 100 89 23:05–05:30 (good, 6.42 h) 42.9° 02:20 10.94 24% 90.6°
2025-11-15 Sat 89 44 39 04:00–05:00 (good, 1.0 h) 42.9° 02:15 10.97 16% 100.7°
2025-11-16 Sun 89 16 14 23:00–00:00 (marginal, 1.0 h) 42.9° 02:10 10.99 10% 110.6°
2025-11-17 Mon 89 0 0 — 42.9° 02:10 11.02 5% 120.0°
2025-11-18 Tue 89 0 0 — 42.9° 02:05 11.05 2% 128.8°
2025-11-19 Wed 89 6 6 02:00–03:00 (marginal, 1.0 h) 42.9° 02:00 11.08 0% 136.5°
2025-11-20 Thu 89 5 4 — 42.9° 01:55 11.1 0% 142.5°
2025-11-21 Fri 89 0 0 — 42.9° 01:55 11.13 3% 145.9°
2025-11-22 Sat 89 0 0 — 42.9° 01:50 11.15 6% 145.9°
2025-11-23 Sun 89 100 89 22:30–05:05 (good, 6.58 h) 42.9° 01:45 11.17 12% 142.3°
2025-11-24 Mon 89 56 50 22:25–02:00 (good, 3.58 h) 42.9° 01:40 11.2 18% 136.0°
2025-11-25 Tue 89 0 0 — 42.9° 01:35 11.22 27% 127.8°
2025-11-26 Wed 89 0 0 — 42.9° 01:35 11.24 36% 118.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-10-28&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.