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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: 03-30 (10), 03-31 (8), 04-01 (5), 04-02 (4), 04-03 (2) — by astronomy; check the weather when the night is within four days.
2028-03-30astronomy score per night — click a bar for that night2028-04-28
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2028-03-30 Thu 10 — unknown 21:25–21:30 (good, 0.08 h) 42.9° 18:25 8.16 21% 36.9°
2028-03-31 Fri 8 — unknown 21:25–22:10 (marginal, 0.75 h) 42.9° 18:20 8.11 30% 32.3°
2028-04-01 Sat 5 — unknown 21:25–22:05 (marginal, 0.67 h) 42.9° 18:15 8.05 40% 32.1°
2028-04-02 Sun 4 — unknown 21:25–21:50 (marginal, 0.42 h) 42.9° 18:10 8.0 51% 36.8°
2028-04-03 Mon 2 — unknown 21:30–21:40 (marginal, 0.17 h) 42.9° 18:10 7.94 63% 45.0°
2028-04-04 Tue 2 — unknown 21:30–21:35 (marginal, 0.08 h) 42.9° 18:05 7.89 73% 55.4°
2028-04-05 Wed 2 — unknown 21:30–21:35 (marginal, 0.08 h) 42.9° 18:00 7.83 83% 67.0°
2028-04-06 Thu 2 — unknown 21:30–21:35 (marginal, 0.08 h) 42.9° 17:55 7.78 91% 79.4°
2028-04-07 Fri 2 — unknown 21:35–21:40 (marginal, 0.08 h) 42.9° 17:50 7.72 97% 92.1°
2028-04-08 Sat 2 — unknown 21:35–21:40 (marginal, 0.08 h) 42.9° 17:50 7.66 100% 104.7°
2028-04-09 Sun 1 — unknown — 42.9° 17:45 7.61 100% 116.9°
2028-04-10 Mon 1 — unknown — 42.9° 17:40 7.55 97% 128.2°
2028-04-11 Tue 1 — unknown — 42.9° 17:35 7.49 92% 137.9°
2028-04-12 Wed 1 — unknown — 42.9° 17:30 7.44 85% 145.1°
2028-04-13 Thu 1 — unknown — 42.9° 17:30 7.38 76% 148.4°
2028-04-14 Fri 0 — unknown — 42.9° 17:25 7.32 67% 147.1°
2028-04-15 Sat 0 — unknown — 42.9° 17:20 7.26 57% 142.0°
2028-04-16 Sun 0 — unknown — 42.9° 17:15 7.21 48% 134.6°
2028-04-17 Mon 0 — unknown — 42.9° 17:15 7.15 38% 125.9°
2028-04-18 Tue 0 — unknown — 42.9° 17:10 7.09 29% 116.5°
2028-04-19 Wed 0 — unknown — 42.9° 17:05 7.03 21% 106.7°
2028-04-20 Thu 0 — unknown — 42.9° 17:00 6.97 14% 96.7°
2028-04-21 Fri 0 — unknown — 42.9° 16:55 6.92 8% 86.5°
2028-04-22 Sat 0 — unknown — 42.9° 16:55 6.86 4% 76.2°
2028-04-23 Sun 0 — unknown — 42.9° 16:50 6.8 1% 66.0°
2028-04-24 Mon 0 — unknown — 42.9° 16:45 6.74 0% 55.9°
2028-04-25 Tue 0 — unknown — 42.9° 16:40 6.68 1% 46.5°
2028-04-26 Wed 0 — unknown — 42.9° 16:35 6.62 5% 38.4°
2028-04-27 Thu 0 — unknown — 42.9° 16:35 6.57 10% 32.8°
2028-04-28 Fri 0 — unknown — 42.9° 16:30 6.51 18% 31.5°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-03-30&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.