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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: 06-10 (30), 06-09 (29), 06-08 (28), 06-07 (26), 06-06 (25) — by astronomy; check the weather when the night is within four days.
2040-05-12astronomy score per night — click a bar for that night2040-06-10
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
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°
2040-05-23 Wed 9 — unknown 03:20–03:55 (marginal, 0.58 h) 89.7° 09:55 5.15 91% 143.6°
2040-05-24 Thu 9 — unknown 03:15–03:55 (marginal, 0.67 h) 89.6° 09:50 5.1 97% 142.0°
2040-05-25 Fri 9 — unknown 03:10–03:50 (marginal, 0.67 h) 89.6° 09:50 5.05 100% 136.0°
2040-05-26 Sat 10 — unknown 03:05–04:40 (marginal, 1.58 h) 89.8° 09:45 5.01 100% 127.1°
2040-05-27 Sun 11 — unknown 03:05–04:40 (marginal, 1.58 h) 89.8° 09:40 4.97 97% 116.5°
2040-05-28 Mon 11 — unknown 03:00–04:40 (marginal, 1.67 h) 89.7° 09:35 4.93 91% 105.0°
2040-05-29 Tue 11 — unknown 02:55–04:35 (marginal, 1.67 h) 89.5° 09:30 4.89 84% 93.1°
2040-05-30 Wed 10 — unknown 02:50–03:45 (marginal, 0.92 h) 89.7° 09:30 4.85 74% 81.4°
2040-05-31 Thu 11 — unknown 02:50–04:35 (marginal, 1.75 h) 89.8° 09:25 4.81 63% 70.1°
2040-06-01 Fri 13 — unknown 03:40–03:45 (good, 0.08 h) 89.8° 09:20 4.77 52% 59.6°
2040-06-02 Sat 15 — unknown 03:30–03:45 (good, 0.25 h) 89.6° 09:15 4.74 41% 50.2°
2040-06-03 Sun 18 — unknown 03:20–03:45 (good, 0.42 h) 89.5° 09:15 4.71 31% 42.7°
2040-06-04 Mon 23 — unknown 03:05–03:40 (good, 0.58 h) 89.7° 09:10 4.67 21% 37.8°
2040-06-05 Tue 24 — unknown 03:00–03:40 (good, 0.67 h) 89.8° 09:05 4.64 14% 36.4°
2040-06-06 Wed 25 — unknown 02:55–03:40 (good, 0.75 h) 89.7° 09:00 4.62 8% 38.7°
2040-06-07 Thu 26 — unknown 02:55–03:40 (good, 0.75 h) 89.6° 08:55 4.59 3% 43.9°
2040-06-08 Fri 28 — unknown 02:50–03:40 (good, 0.83 h) 89.6° 08:55 4.57 1% 51.1°
2040-06-09 Sat 29 — unknown 02:45–03:40 (good, 0.92 h) 89.7° 08:50 4.54 0% 59.4°
2040-06-10 Sun 30 — unknown 02:40–03:40 (good, 1.0 h) 89.8° 08:45 4.52 1% 68.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-05-12&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.