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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: 03-13 (43), 03-14 (41), 03-15 (39), 03-16 (38), 03-17 (36) — by astronomy; check the weather when the night is within four days.
2028-03-13astronomy score per night — click a bar for that night2028-04-11
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2028-03-13 Mon 43 — unknown 20:00–21:50 (good, 1.83 h) 42.9° 18:30 9.05 88% 122.0°
2028-03-14 Tue 41 — unknown 20:00–21:45 (good, 1.75 h) 42.9° 18:25 9.0 80% 132.5°
2028-03-15 Wed 39 — unknown 20:05–21:40 (good, 1.58 h) 42.9° 18:25 8.95 70% 141.1°
2028-03-16 Thu 38 — unknown 20:05–21:40 (good, 1.58 h) 42.9° 18:20 8.9 60% 146.7°
2028-03-17 Fri 36 — unknown 20:05–21:35 (good, 1.5 h) 42.9° 18:15 8.85 50% 148.2°
2028-03-18 Sat 34 — unknown 20:05–21:30 (good, 1.42 h) 42.9° 18:10 8.8 41% 145.5°
2028-03-19 Sun 32 — unknown 20:10–21:25 (good, 1.25 h) 42.9° 18:05 8.75 31% 139.6°
2028-03-20 Mon 31 — unknown 20:10–21:20 (good, 1.17 h) 42.9° 18:05 8.7 23% 131.9°
2028-03-21 Tue 29 — unknown 20:10–21:20 (good, 1.17 h) 42.9° 18:00 8.64 16% 123.0°
2028-03-22 Wed 28 — unknown 20:10–21:15 (good, 1.08 h) 42.9° 17:55 8.59 9% 113.5°
2028-03-23 Thu 26 — unknown 20:15–21:10 (good, 0.92 h) 42.9° 17:50 8.54 5% 103.7°
2028-03-24 Fri 24 — unknown 20:15–21:05 (good, 0.83 h) 42.9° 17:45 8.49 2% 93.7°
2028-03-25 Sat 23 — unknown 20:15–21:00 (good, 0.75 h) 42.9° 17:45 8.43 0% 83.5°
2028-03-26 Sun 22 — unknown 21:15–22:00 (good, 0.75 h) 42.9° 18:40 8.38 1% 73.2°
2028-03-27 Mon 19 — unknown 21:20–21:55 (good, 0.58 h) 42.9° 18:35 8.33 3% 63.1°
2028-03-28 Tue 16 — unknown 21:20–21:50 (good, 0.5 h) 42.9° 18:30 8.27 7% 53.4°
2028-03-29 Wed 14 — unknown 21:20–21:40 (good, 0.33 h) 42.9° 18:25 8.22 13% 44.4°
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°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-03-13&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.