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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 Andromeda Galaxy: 09-15 (100), 09-16 (100), 09-17 (100), 09-18 (100), 09-19 (100) — by astronomy; check the weather when the night is within four days.
2025-09-14astronomy score per night — click a bar for that night2025-10-13
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-09-14 Sun 99 33 33 02:00–04:00 (good, 2.0 h) 89.6° 02:30 8.33 44% 62.9°
2025-09-15 Mon 100 100 100 21:05–05:30 (good, 8.42 h) 89.7° 02:25 8.38 34% 74.5°
2025-09-16 Tue 100 100 100 21:05–05:30 (good, 8.42 h) 89.7° 02:20 8.44 24% 86.2°
2025-09-17 Wed 100 92 92 21:05–05:35 (good, 8.5 h) 89.6° 02:15 8.49 15% 97.7°
2025-09-18 Thu 100 100 100 21:00–05:35 (good, 8.58 h) 89.5° 02:15 8.54 8% 108.9°
2025-09-19 Fri 100 98 98 21:00–05:35 (good, 8.58 h) 89.6° 02:10 8.59 4% 119.7°
2025-09-20 Sat 100 76 76 01:00–05:35 (good, 4.58 h) 89.7° 02:05 8.64 1% 129.8°
2025-09-21 Sun 100 100 100 20:55–05:40 (good, 8.75 h) 89.7° 02:00 8.7 0% 138.7°
2025-09-22 Mon 100 100 100 20:55–05:40 (good, 8.75 h) 89.5° 01:55 8.75 1% 145.7°
2025-09-23 Tue 100 100 100 20:50–05:40 (good, 8.83 h) 89.5° 01:55 8.8 4% 149.6°
2025-09-24 Wed 100 89 89 20:50–04:00 (good, 7.17 h) 89.7° 01:50 8.85 9% 149.5°
2025-09-25 Thu 100 0 0 — 89.7° 01:45 8.9 15% 145.4°
2025-09-26 Fri 100 19 19 00:00–01:00 (good, 1.0 h) 89.6° 01:40 8.95 22% 138.6°
2025-09-27 Sat 100 12 12 20:45–21:00 (good, 0.25 h) 89.5° 01:35 9.0 31% 130.2°
2025-09-28 Sun 100 0 0 — 89.6° 01:35 9.05 40% 120.8°
2025-09-29 Mon 100 4 4 — 89.7° 01:30 9.09 49% 110.8°
2025-09-30 Tue 100 60 60 00:00–05:50 (good, 5.83 h) 89.7° 01:25 9.14 59% 100.2°
2025-10-01 Wed 100 0 0 — 89.6° 01:20 9.19 69% 89.3°
2025-10-02 Thu 100 0 0 — 89.5° 01:20 9.24 78% 78.0°
2025-10-03 Fri 100 0 0 — 89.6° 01:15 9.29 86% 66.6°
2025-10-04 Sat 92 96 88 02:40–05:50 (good, 3.17 h) 89.7° 01:10 9.33 93% 55.1°
2025-10-05 Sun 54 39 21 20:30–23:00 (marginal, 2.5 h) 89.7° 01:05 9.38 98% 44.3°
2025-10-06 Mon 40 0 0 — 89.5° 01:00 9.43 100% 35.3°
2025-10-07 Tue 35 0 0 — 89.5° 01:00 9.47 99% 30.3°
2025-10-08 Wed 43 0 0 — 89.7° 00:55 9.52 95% 31.6°
2025-10-09 Thu 57 94 54 20:25–04:00 (marginal, 7.58 h) 89.7° 00:50 9.57 89% 38.5°
2025-10-10 Fri 90 65 59 22:00–22:55 (good, 0.92 h) 89.6° 00:45 9.61 80% 48.5°
2025-10-11 Sat 97 31 30 20:20–22:00 (good, 1.67 h) 89.5° 00:40 9.66 70% 59.9°
2025-10-12 Sun 100 41 41 01:00–03:00 (good, 2.0 h) 89.6° 00:40 9.7 59% 71.7°
2025-10-13 Mon 100 6 6 — 89.7° 00:35 9.74 48% 83.5°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-09-14&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.