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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: 05-17 (6), 05-14 (5), 05-15 (5), 05-16 (5), 05-13 (4) — by astronomy; check the weather when the night is within four days.
2026-04-18astronomy score per night — click a bar for that night2026-05-17
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-04-18 Sat 0 97 0 — 89.7° 12:20 7.12 3% 34.6°
2026-04-19 Sun 0 54 0 — 89.7° 12:15 7.06 9% 43.7°
2026-04-20 Mon 0 36 0 — 89.6° 12:10 7.0 16% 54.9°
2026-04-21 Tue 0 0 0 — 89.5° 12:05 6.95 26% 67.0°
2026-04-22 Wed 0 0 0 — 89.7° 12:00 6.89 37% 79.2°
2026-04-23 Thu 0 0 0 — 89.7° 12:00 6.83 48% 91.4°
2026-04-24 Fri 0 100 0 — 89.6° 11:50 6.77 59% 103.3°
2026-04-25 Sat 1 100 1 — 89.5° 11:50 6.71 69% 114.7°
2026-04-26 Sun 1 100 1 — 89.6° 11:45 6.65 78% 125.5°
2026-04-27 Mon 1 31 0 — 89.7° 11:40 6.6 86% 135.3°
2026-04-28 Tue 1 96 1 — 89.7° 11:35 6.54 92% 143.5°
2026-04-29 Wed 1 0 0 — 89.5° 11:30 6.48 97% 149.0°
2026-04-30 Thu 1 0 0 — 89.5° 11:30 6.42 99% 150.5°
2026-05-01 Fri 1 39 0 — 89.7° 11:25 6.36 100% 147.7°
2026-05-02 Sat 1 0 0 — 89.7° 11:20 6.31 98% 141.5°
2026-05-03 Sun 1 100 1 — 89.6° 11:15 6.25 95% 133.3°
2026-05-04 Mon 1 88 1 — 89.5° 11:10 6.19 91% 124.1°
2026-05-05 Tue 1 100 1 — 89.6° 11:10 6.13 84% 114.3°
2026-05-06 Wed 1 94 1 — 89.7° 11:05 6.08 77% 104.2°
2026-05-07 Thu 1 0 0 — 89.7° 11:00 6.02 69% 93.9°
2026-05-08 Fri 1 25 0 — 89.6° 10:55 5.96 59% 83.3°
2026-05-09 Sat 2 35 1 — 89.5° 10:55 5.91 50% 72.6°
2026-05-10 Sun 2 56 1 — 89.6° 10:50 5.85 40% 61.9°
2026-05-11 Mon 3 0 0 — 89.7° 10:45 5.79 30% 51.3°
2026-05-12 Tue 3 100 3 04:45–04:55 (marginal, 0.17 h) 89.7° 10:40 5.74 20% 41.4°
2026-05-13 Wed 4 0 0 — 89.5° 10:35 5.68 12% 33.3°
2026-05-14 Thu 5 5 0 — 89.5° 10:35 5.63 5% 29.4°
2026-05-15 Fri 5 10 1 — 89.7° 10:30 5.58 1% 31.7°
2026-05-16 Sat 5 97 5 04:25–04:50 (marginal, 0.42 h) 89.7° 10:25 5.52 0% 39.5°
2026-05-17 Sun 6 0 0 — 89.6° 10:20 5.47 2% 50.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-04-18&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.