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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 (9), 05-23 (7), 05-21 (6), 05-22 (6), 05-17 (5) — by astronomy; check the weather when the night is within four days.
2041-04-25astronomy score per night — click a bar for that night2041-05-24
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2041-04-25 Thu 0 — unknown — 89.6° 11:45 6.69 26% 62.6°
2041-04-26 Fri 1 — unknown — 89.6° 11:45 6.63 16% 52.1°
2041-04-27 Sat 1 — unknown — 89.8° 11:40 6.57 8% 43.0°
2041-04-28 Sun 1 — unknown — 89.8° 11:35 6.52 3% 36.8°
2041-04-29 Mon 1 — unknown — 89.7° 11:30 6.46 0% 34.8°
2041-04-30 Tue 1 — unknown — 89.5° 11:25 6.4 0% 37.6°
2041-05-01 Wed 1 — unknown — 89.7° 11:25 6.34 2% 44.0°
2041-05-02 Thu 1 — unknown — 89.8° 11:20 6.28 7% 52.5°
2041-05-03 Fri 1 — unknown — 89.8° 11:15 6.23 13% 61.9°
2041-05-04 Sat 1 — unknown — 89.6° 11:10 6.17 21% 71.8°
2041-05-05 Sun 2 — unknown — 89.5° 11:10 6.11 29% 81.7°
2041-05-06 Mon 2 — unknown 05:00–05:05 (marginal, 0.08 h) 89.7° 11:05 6.05 38% 91.6°
2041-05-07 Tue 2 — unknown 04:55–05:00 (marginal, 0.08 h) 89.8° 11:00 6.0 48% 101.4°
2041-05-08 Wed 2 — unknown 04:50–05:00 (marginal, 0.17 h) 89.7° 10:55 5.94 57% 110.9°
2041-05-09 Thu 2 — unknown 04:50–05:00 (marginal, 0.17 h) 89.6° 10:50 5.89 66% 120.1°
2041-05-10 Fri 3 — unknown 04:45–05:00 (marginal, 0.25 h) 89.6° 10:50 5.83 75% 128.7°
2041-05-11 Sat 3 — unknown 04:40–04:55 (marginal, 0.25 h) 89.8° 10:45 5.77 83% 136.3°
2041-05-12 Sun 3 — unknown 04:45–04:55 (marginal, 0.17 h) 89.8° 10:40 5.72 90% 142.2°
2041-05-13 Mon 4 — unknown 04:40–04:55 (marginal, 0.25 h) 89.7° 10:35 5.67 95% 145.1°
2041-05-14 Tue 4 — unknown 03:55–04:10 (marginal, 0.25 h) 89.5° 10:30 5.61 99% 144.1°
2041-05-15 Wed 4 — unknown 03:50–04:05 (marginal, 0.25 h) 89.7° 10:30 5.56 100% 139.2°
2041-05-16 Thu 4 — unknown 04:30–04:50 (marginal, 0.33 h) 89.8° 10:25 5.51 99% 131.4°
2041-05-17 Fri 5 — unknown 03:45–04:05 (marginal, 0.33 h) 89.8° 10:20 5.45 96% 121.8°
2041-05-18 Sat 5 — unknown 03:40–04:00 (marginal, 0.33 h) 89.6° 10:15 5.4 90% 111.0°
2041-05-19 Sun 5 — unknown 03:35–04:00 (marginal, 0.42 h) 89.5° 10:15 5.35 82% 99.7°
2041-05-20 Mon 5 — unknown 03:30–04:00 (marginal, 0.5 h) 89.7° 10:10 5.3 72% 88.1°
2041-05-21 Tue 6 — unknown 03:30–04:00 (marginal, 0.5 h) 89.8° 10:05 5.25 62% 76.5°
2041-05-22 Wed 6 — unknown 03:25–03:55 (marginal, 0.5 h) 89.7° 10:00 5.2 50% 65.2°
2041-05-23 Thu 7 — unknown 03:20–03:55 (marginal, 0.58 h) 89.6° 09:55 5.16 39% 54.6°
2041-05-24 Fri 9 — unknown 03:15–03:55 (marginal, 0.67 h) 89.6° 09:55 5.11 28% 45.2°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-25&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.