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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: 07-17 (100), 07-18 (100), 07-19 (100), 07-20 (100), 07-21 (100) — by astronomy; check the weather when the night is within four days.
2026-07-09astronomy score per night — click a bar for that night2026-08-07
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-07-09 Thu 63 92 58 00:55–03:50 (good, 2.92 h) 89.5° 06:55 4.76 27% 32.7°
2026-07-10 Fri 76 100 76 00:45–03:55 (good, 3.17 h) 89.7° 06:50 4.8 17% 41.0°
2026-07-11 Sat 84 100 84 00:40–03:55 (good, 3.25 h) 89.7° 06:45 4.84 9% 51.9°
2026-07-12 Sun 90 91 82 01:00–03:55 (good, 2.92 h) 89.7° 06:40 4.87 3% 64.2°
2026-07-13 Mon 92 90 83 00:45–03:55 (good, 3.17 h) 89.5° 06:35 4.91 0% 77.2°
2026-07-14 Tue 96 99 95 00:30–04:00 (good, 3.5 h) 89.6° 06:35 4.96 0% 90.3°
2026-07-15 Wed 97 63 61 02:00–04:00 (good, 2.0 h) 89.7° 06:30 5.0 3% 103.2°
2026-07-16 Thu 99 13 13 04:00–04:50 (marginal, 0.83 h) 89.7° 06:25 5.04 9% 115.5°
2026-07-17 Fri 100 98 98 00:20–04:00 (good, 3.67 h) 89.6° 06:20 5.08 16% 127.1°
2026-07-18 Sat 100 93 93 00:15–04:05 (good, 3.83 h) 89.5° 06:15 5.13 25% 137.3°
2026-07-19 Sun 100 99 99 00:10–04:05 (good, 3.92 h) 89.6° 06:15 5.18 35% 145.4°
2026-07-20 Mon 100 53 53 02:00–04:05 (good, 2.08 h) 89.7° 06:10 5.22 45% 150.3°
2026-07-21 Tue 100 72 72 00:15–03:00 (good, 2.75 h) 89.7° 06:05 5.27 55% 150.7°
2026-07-22 Wed 100 98 98 00:05–04:10 (good, 4.08 h) 89.6° 06:00 5.32 64% 146.7°
2026-07-23 Thu 100 64 64 00:10–02:00 (good, 1.83 h) 89.5° 06:00 5.37 73% 139.9°
2026-07-24 Fri 100 0 0 — 89.7° 05:55 5.42 81% 131.3°
2026-07-25 Sat 100 86 86 01:00–04:15 (good, 3.25 h) 89.7° 05:50 5.47 88% 121.9°
2026-07-26 Sun 100 88 88 00:00–04:15 (good, 4.25 h) 89.7° 05:45 5.52 93% 112.0°
2026-07-27 Mon 85 99 84 00:05–04:20 (good, 4.25 h) 89.5° 05:40 5.58 97% 101.7°
2026-07-28 Tue 75 90 67 01:15–04:20 (good, 3.08 h) 89.6° 05:40 5.63 100% 91.1°
2026-07-29 Wed 62 100 62 01:20–04:20 (good, 3.0 h) 89.7° 05:35 5.68 100% 80.4°
2026-07-30 Thu 50 100 50 02:45–04:20 (good, 1.58 h) 89.7° 05:30 5.74 98% 69.7°
2026-07-31 Fri 42 100 42 23:00–04:25 (marginal, 5.42 h) 89.6° 05:25 5.79 95% 59.1°
2026-08-01 Sat 37 100 37 22:55–04:25 (marginal, 5.5 h) 89.5° 05:20 5.85 89% 48.9°
2026-08-02 Sun 37 99 37 22:50–04:25 (marginal, 5.58 h) 89.6° 05:20 5.9 82% 39.6°
2026-08-03 Mon 42 99 42 22:40–04:30 (marginal, 5.83 h) 89.7° 05:15 5.96 73% 32.3°
2026-08-04 Tue 58 96 56 22:35–04:30 (marginal, 5.92 h) 89.7° 05:10 6.01 63% 28.9°
2026-08-05 Wed 81 93 75 00:05–04:30 (good, 4.42 h) 89.6° 05:05 6.07 52% 31.0°
2026-08-06 Thu 85 90 77 23:10–04:35 (good, 5.42 h) 89.5° 05:05 6.13 40% 38.0°
2026-08-07 Fri 91 98 89 23:00–04:35 (good, 5.58 h) 89.6° 05:00 6.18 30% 48.0°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-07-09&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.