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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: 05-13 (4), 05-14 (4), 05-15 (4), 05-10 (3), 05-11 (3) — by astronomy; check the weather when the night is within four days.
2041-04-16astronomy score per night — click a bar for that night2041-05-15
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2041-04-16 Tue 0 — unknown — 89.7° 12:25 7.21 100% 145.2°
2041-04-17 Wed 0 — unknown — 89.5° 12:25 7.16 98% 142.9°
2041-04-18 Thu 0 — unknown — 89.7° 12:20 7.1 94% 137.0°
2041-04-19 Fri 0 — unknown — 89.8° 12:15 7.04 88% 128.7°
2041-04-20 Sat 0 — unknown — 89.8° 12:10 6.98 79% 118.9°
2041-04-21 Sun 0 — unknown — 89.6° 12:05 6.92 70% 108.2°
2041-04-22 Mon 0 — unknown — 89.7° 12:00 6.87 59% 97.0°
2041-04-23 Tue 0 — unknown — 89.8° 11:55 6.81 48% 85.4°
2041-04-24 Wed 0 — unknown — 89.7° 11:50 6.75 36% 73.9°
2041-04-25 Thu 0 — unknown — 89.6° 11:45 6.69 26% 62.6°
2041-04-26 Fri 1 — unknown — 89.6° 11:45 6.63 16% 52.1°
2041-04-27 Sat 1 — unknown — 89.8° 11:40 6.57 8% 43.0°
2041-04-28 Sun 1 — unknown — 89.8° 11:35 6.52 3% 36.8°
2041-04-29 Mon 1 — unknown — 89.7° 11:30 6.46 0% 34.8°
2041-04-30 Tue 1 — unknown — 89.5° 11:25 6.4 0% 37.6°
2041-05-01 Wed 1 — unknown — 89.7° 11:25 6.34 2% 44.0°
2041-05-02 Thu 1 — unknown — 89.8° 11:20 6.28 7% 52.5°
2041-05-03 Fri 1 — unknown — 89.8° 11:15 6.23 13% 61.9°
2041-05-04 Sat 1 — unknown — 89.6° 11:10 6.17 21% 71.8°
2041-05-05 Sun 2 — unknown — 89.5° 11:10 6.11 29% 81.7°
2041-05-06 Mon 2 — unknown 05:00–05:05 (marginal, 0.08 h) 89.7° 11:05 6.05 38% 91.6°
2041-05-07 Tue 2 — unknown 04:55–05:00 (marginal, 0.08 h) 89.8° 11:00 6.0 48% 101.4°
2041-05-08 Wed 2 — unknown 04:50–05:00 (marginal, 0.17 h) 89.7° 10:55 5.94 57% 110.9°
2041-05-09 Thu 2 — unknown 04:50–05:00 (marginal, 0.17 h) 89.6° 10:50 5.89 66% 120.1°
2041-05-10 Fri 3 — unknown 04:45–05:00 (marginal, 0.25 h) 89.6° 10:50 5.83 75% 128.7°
2041-05-11 Sat 3 — unknown 04:40–04:55 (marginal, 0.25 h) 89.8° 10:45 5.77 83% 136.3°
2041-05-12 Sun 3 — unknown 04:45–04:55 (marginal, 0.17 h) 89.8° 10:40 5.72 90% 142.2°
2041-05-13 Mon 4 — unknown 04:40–04:55 (marginal, 0.25 h) 89.7° 10:35 5.67 95% 145.1°
2041-05-14 Tue 4 — unknown 03:55–04:10 (marginal, 0.25 h) 89.5° 10:30 5.61 99% 144.1°
2041-05-15 Wed 4 — unknown 03:50–04:05 (marginal, 0.25 h) 89.7° 10:30 5.56 100% 139.2°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-16&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.