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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: 05-27 (14), 05-25 (12), 05-26 (12), 05-24 (11), 05-23 (10) — by astronomy; check the weather when the night is within four days.
2025-04-28astronomy score per night — click a bar for that night2025-05-27
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-04-28 Mon 1 100 1 — 89.7° 11:35 6.52 2% 38.3°
2025-04-29 Tue 1 100 1 — 89.7° 11:30 6.47 7% 48.2°
2025-04-30 Wed 1 38 0 — 89.5° 11:25 6.41 14% 59.6°
2025-05-01 Thu 1 54 1 — 89.5° 11:25 6.35 23% 71.3°
2025-05-02 Fri 1 100 1 — 89.7° 11:20 6.29 33% 83.1°
2025-05-03 Sat 1 100 1 — 89.7° 11:15 6.23 43% 94.5°
2025-05-04 Sun 1 37 0 — 89.6° 11:10 6.18 54% 105.6°
2025-05-05 Mon 2 98 2 — 89.5° 11:05 6.12 64% 116.1°
2025-05-06 Tue 2 0 0 — 89.6° 11:05 6.06 73% 125.9°
2025-05-07 Wed 2 5 0 — 89.7° 11:00 6.0 81% 134.9°
2025-05-08 Thu 2 0 0 — 89.7° 10:55 5.95 88% 142.4°
2025-05-09 Fri 2 0 0 — 89.6° 10:50 5.89 93% 147.7°
2025-05-10 Sat 3 0 0 — 89.5° 10:50 5.84 97% 149.4°
2025-05-11 Sun 3 0 0 — 89.6° 10:45 5.78 99% 147.2°
2025-05-12 Mon 3 0 0 — 89.7° 10:40 5.73 100% 141.6°
2025-05-13 Tue 3 0 0 — 89.7° 10:35 5.67 98% 133.9°
2025-05-14 Wed 4 100 4 03:55–04:10 (marginal, 0.25 h) 89.5° 10:30 5.62 95% 124.8°
2025-05-15 Thu 4 0 0 — 89.5° 10:30 5.56 90% 115.0°
2025-05-16 Fri 4 0 0 — 89.7° 10:25 5.51 84% 104.6°
2025-05-17 Sat 4 0 0 — 89.7° 10:20 5.46 76% 93.8°
2025-05-18 Sun 4 100 4 03:40–04:00 (marginal, 0.33 h) 89.6° 10:15 5.41 66% 82.8°
2025-05-19 Mon 5 100 5 03:35–04:00 (marginal, 0.42 h) 89.5° 10:10 5.36 56% 71.6°
2025-05-20 Tue 6 72 4 03:30–04:00 (marginal, 0.5 h) 89.6° 10:10 5.31 45% 60.4°
2025-05-21 Wed 7 68 5 03:45–04:00 (marginal, 0.25 h) 89.7° 10:05 5.26 34% 49.6°
2025-05-22 Thu 7 89 6 03:25–03:55 (marginal, 0.5 h) 89.7° 10:00 5.21 24% 39.8°
2025-05-23 Fri 10 21 2 — 89.6° 09:55 5.16 15% 32.7°
2025-05-24 Sat 11 0 0 — 89.5° 09:55 5.12 7% 30.6°
2025-05-25 Sun 12 0 0 — 89.6° 09:50 5.07 2% 34.8°
2025-05-26 Mon 12 80 10 03:10–03:50 (marginal, 0.67 h) 89.7° 09:45 5.03 0% 43.6°
2025-05-27 Tue 14 100 14 03:35–03:50 (good, 0.25 h) 89.7° 09:40 4.98 1% 54.6°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-04-28&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.