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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: 05-20 (8), 05-21 (8), 05-22 (8), 05-19 (7), 05-16 (6) — by astronomy; check the weather when the night is within four days.
2040-04-23astronomy score per night — click a bar for that night2040-05-22
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2040-04-23 Mon 0 — unknown — 89.7° 11:55 6.79 88% 130.2°
2040-04-24 Tue 0 — unknown — 89.8° 11:50 6.74 94% 137.6°
2040-04-25 Wed 0 — unknown — 89.7° 11:45 6.68 98% 142.5°
2040-04-26 Thu 1 — unknown — 89.5° 11:40 6.62 100% 143.5°
2040-04-27 Fri 1 — unknown — 89.6° 11:40 6.56 99% 140.0°
2040-04-28 Sat 1 — unknown — 89.8° 11:35 6.5 96% 132.7°
2040-04-29 Sun 1 — unknown — 89.8° 11:30 6.44 90% 123.2°
2040-04-30 Mon 1 — unknown — 89.7° 11:25 6.39 81% 112.5°
2040-05-01 Tue 1 — unknown — 89.5° 11:25 6.33 71% 101.2°
2040-05-02 Wed 1 — unknown — 89.7° 11:20 6.27 60% 89.7°
2040-05-03 Thu 1 — unknown — 89.8° 11:15 6.21 49% 78.4°
2040-05-04 Fri 1 — unknown — 89.8° 11:10 6.16 38% 67.5°
2040-05-05 Sat 1 — unknown — 89.6° 11:05 6.1 27% 57.3°
2040-05-06 Sun 2 — unknown — 89.6° 11:05 6.04 18% 48.3°
2040-05-07 Mon 2 — unknown 04:55–05:00 (marginal, 0.08 h) 89.7° 11:00 5.98 11% 41.3°
2040-05-08 Tue 2 — unknown 04:50–05:00 (marginal, 0.17 h) 89.8° 10:55 5.93 5% 37.1°
2040-05-09 Wed 2 — unknown 04:45–05:00 (marginal, 0.25 h) 89.7° 10:50 5.87 2% 36.6°
2040-05-10 Thu 3 — unknown 04:45–04:55 (marginal, 0.17 h) 89.6° 10:45 5.82 0% 39.8°
2040-05-11 Fri 4 — unknown 04:40–04:55 (marginal, 0.25 h) 89.6° 10:45 5.76 1% 45.7°
2040-05-12 Sat 4 — unknown 04:35–04:55 (marginal, 0.33 h) 89.8° 10:40 5.71 3% 53.3°
2040-05-13 Sun 4 — unknown 04:30–04:55 (marginal, 0.42 h) 89.8° 10:35 5.65 7% 61.9°
2040-05-14 Mon 5 — unknown 03:55–04:10 (marginal, 0.25 h) 89.7° 10:30 5.6 13% 71.0°
2040-05-15 Tue 5 — unknown 04:25–04:50 (marginal, 0.42 h) 89.5° 10:25 5.55 20% 80.3°
2040-05-16 Wed 6 — unknown 04:20–04:50 (marginal, 0.5 h) 89.7° 10:25 5.49 28% 89.8°
2040-05-17 Thu 6 — unknown 04:15–04:50 (marginal, 0.58 h) 89.8° 10:20 5.44 37% 99.4°
2040-05-18 Fri 6 — unknown 04:10–04:45 (marginal, 0.58 h) 89.8° 10:15 5.39 46% 108.9°
2040-05-19 Sat 7 — unknown 04:10–04:45 (marginal, 0.58 h) 89.6° 10:10 5.34 56% 118.1°
2040-05-20 Sun 8 — unknown 04:05–04:45 (marginal, 0.67 h) 89.5° 10:10 5.29 66% 127.0°
2040-05-21 Mon 8 — unknown 04:00–04:45 (marginal, 0.75 h) 89.7° 10:05 5.24 75% 134.9°
2040-05-22 Tue 8 — unknown 04:05–04:45 (marginal, 0.67 h) 89.8° 10:00 5.19 84% 140.9°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-04-23&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.