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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 Great Orion Nebula: 09-05 (12), 09-04 (8), 09-03 (6), 08-26 (4), 08-27 (4) — by astronomy; check the weather when the night is within four days.
2026-08-07astronomy score per night — click a bar for that night2026-09-05
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-08-07 Fri 0 0 0 — 42.9° 09:50 6.18 30% 36.2°
2026-08-08 Sat 0 0 0 — 42.9° 09:45 6.24 19% 33.5°
2026-08-09 Sun 0 0 0 — 42.9° 09:45 6.3 11% 36.2°
2026-08-10 Mon 0 0 0 — 42.9° 09:40 6.35 5% 43.4°
2026-08-11 Tue 0 100 0 — 42.9° 09:35 6.41 1% 53.2°
2026-08-12 Wed 0 100 0 — 42.9° 09:30 6.47 0% 64.3°
2026-08-13 Thu 0 0 0 — 42.9° 09:25 6.53 2% 75.8°
2026-08-14 Fri 0 82 0 — 42.9° 09:25 6.58 6% 87.4°
2026-08-15 Sat 0 100 0 — 42.9° 09:20 6.64 12% 98.6°
2026-08-16 Sun 0 100 0 — 42.9° 09:15 6.7 20% 109.4°
2026-08-17 Mon 0 100 0 — 42.9° 09:10 6.76 29% 119.5°
2026-08-18 Tue 0 22 0 — 42.9° 09:05 6.81 39% 128.7°
2026-08-19 Wed 1 100 1 — 42.9° 09:05 6.87 48% 136.6°
2026-08-20 Thu 1 100 1 — 42.9° 09:00 6.93 58% 142.7°
2026-08-21 Fri 1 100 1 — 42.9° 08:55 6.99 67% 146.1°
2026-08-22 Sat 1 100 1 — 42.9° 08:50 7.04 76% 146.0°
2026-08-23 Sun 2 53 1 — 42.9° 08:50 7.1 83% 142.4°
2026-08-24 Mon 2 100 2 05:30–05:40 (marginal, 0.17 h) 42.9° 08:45 7.16 90% 136.1°
2026-08-25 Tue 3 94 3 05:30–05:40 (marginal, 0.17 h) 42.9° 08:40 7.22 95% 128.0°
2026-08-26 Wed 4 98 4 04:50–05:05 (marginal, 0.25 h) 42.9° 08:35 7.27 98% 118.7°
2026-08-27 Thu 4 99 4 04:45–05:05 (marginal, 0.33 h) 42.9° 08:30 7.33 100% 108.6°
2026-08-28 Fri 3 85 3 05:00–05:05 (marginal, 0.08 h) 42.9° 08:30 7.39 99% 98.0°
2026-08-29 Sat 4 0 0 — 42.9° 08:25 7.44 97% 87.1°
2026-08-30 Sun 3 100 3 04:50–05:10 (marginal, 0.33 h) 42.9° 08:20 7.5 92% 76.1°
2026-08-31 Mon 3 100 3 04:50–05:10 (marginal, 0.33 h) 42.9° 08:15 7.56 85% 65.1°
2026-09-01 Tue 4 75 3 — 42.9° 08:10 7.61 76% 54.6°
2026-09-02 Wed 4 0 0 — 42.9° 08:10 7.67 66% 45.1°
2026-09-03 Thu 6 76 5 04:50–05:15 (marginal, 0.42 h) 42.9° 08:05 7.72 55% 37.6°
2026-09-04 Fri 8 100 8 04:20–05:15 (marginal, 0.92 h) 42.9° 08:00 7.78 43% 33.7°
2026-09-05 Sat 12 100 12 05:10–05:15 (good, 0.08 h) 42.9° 07:55 7.83 32% 34.9°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-08-07&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.