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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: 05-24 (11), 05-23 (10), 05-21 (9), 05-22 (9), 05-20 (8) — by astronomy; check the weather when the night is within four days.
2042-04-25astronomy score per night — click a bar for that night2042-05-24
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2042-04-25 Fri 0 — unknown — 89.6° 11:50 6.71 38% 82.4°
2042-04-26 Sat 1 — unknown — 89.8° 11:45 6.65 48% 93.0°
2042-04-27 Sun 1 — unknown — 89.8° 11:40 6.59 58% 103.2°
2042-04-28 Mon 1 — unknown — 89.7° 11:35 6.53 68% 113.1°
2042-04-29 Tue 1 — unknown — 89.5° 11:30 6.47 76% 122.5°
2042-04-30 Wed 1 — unknown — 89.7° 11:30 6.41 84% 131.1°
2042-05-01 Thu 1 — unknown — 89.8° 11:25 6.36 90% 138.6°
2042-05-02 Fri 1 — unknown — 89.8° 11:20 6.3 95% 144.2°
2042-05-03 Sat 1 — unknown — 89.6° 11:15 6.24 98% 146.8°
2042-05-04 Sun 1 — unknown — 89.5° 11:15 6.18 100% 145.8°
2042-05-05 Mon 1 — unknown — 89.7° 11:10 6.13 100% 141.2°
2042-05-06 Tue 1 — unknown — 89.8° 11:05 6.07 97% 134.0°
2042-05-07 Wed 1 — unknown — 89.7° 11:00 6.01 93% 125.2°
2042-05-08 Thu 2 — unknown — 89.6° 10:55 5.96 87% 115.4°
2042-05-09 Fri 2 — unknown — 89.6° 10:55 5.9 79% 104.9°
2042-05-10 Sat 2 — unknown 04:10–04:15 (marginal, 0.08 h) 89.8° 10:50 5.84 70% 93.9°
2042-05-11 Sun 2 — unknown 04:10–04:15 (marginal, 0.08 h) 89.8° 10:45 5.79 60% 82.6°
2042-05-12 Mon 2 — unknown 04:05–04:10 (marginal, 0.08 h) 89.7° 10:40 5.73 49% 71.3°
2042-05-13 Tue 3 — unknown 04:00–04:10 (marginal, 0.17 h) 89.5° 10:35 5.68 37% 60.1°
2042-05-14 Wed 4 — unknown 03:55–04:10 (marginal, 0.25 h) 89.6° 10:35 5.62 27% 49.5°
2042-05-15 Thu 5 — unknown 03:50–04:05 (marginal, 0.25 h) 89.8° 10:30 5.57 17% 40.4°
2042-05-16 Fri 5 — unknown 04:20–04:50 (marginal, 0.5 h) 89.8° 10:25 5.52 9% 34.3°
2042-05-17 Sat 6 — unknown 04:20–04:50 (marginal, 0.5 h) 89.6° 10:20 5.47 3% 33.4°
2042-05-18 Sun 6 — unknown 04:15–04:50 (marginal, 0.58 h) 89.5° 10:20 5.41 0% 37.9°
2042-05-19 Mon 7 — unknown 04:10–04:45 (marginal, 0.58 h) 89.7° 10:15 5.36 0% 46.2°
2042-05-20 Tue 8 — unknown 04:05–04:45 (marginal, 0.67 h) 89.8° 10:10 5.31 3% 56.4°
2042-05-21 Wed 9 — unknown 03:30–04:45 (marginal, 1.25 h) 89.7° 10:05 5.26 8% 67.3°
2042-05-22 Thu 9 — unknown 04:00–04:45 (marginal, 0.75 h) 89.6° 10:00 5.22 15% 78.3°
2042-05-23 Fri 10 — unknown 03:20–04:45 (marginal, 1.42 h) 89.6° 10:00 5.17 23% 89.2°
2042-05-24 Sat 11 — unknown 03:50–03:55 (good, 0.08 h) 89.7° 09:55 5.12 32% 99.9°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-04-25&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.