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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: 03-16 (38), 03-15 (37), 03-17 (36), 03-18 (35), 03-19 (32) — by astronomy; check the weather when the night is within four days.
2044-03-11astronomy score per night — click a bar for that night2044-04-09
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2044-03-11 Fri 15 — unknown 20:00–22:05 (marginal, 2.08 h) 42.9° 18:40 9.14 96% 69.5°
2044-03-12 Sat 20 — unknown 20:00–22:10 (marginal, 2.17 h) 42.9° 18:35 9.09 99% 80.7°
2044-03-13 Sun 24 — unknown 20:00–21:00 (good, 1.0 h) 42.9° 18:30 9.04 100% 91.9°
2044-03-14 Mon 29 — unknown 20:00–21:25 (good, 1.42 h) 42.9° 18:25 8.99 99% 102.9°
2044-03-15 Tue 37 — unknown 20:05–21:30 (good, 1.42 h) 42.9° 18:25 8.94 95% 113.3°
2044-03-16 Wed 38 — unknown 20:05–21:40 (good, 1.58 h) 42.9° 18:20 8.89 90% 123.1°
2044-03-17 Thu 36 — unknown 20:05–21:35 (good, 1.5 h) 42.9° 18:15 8.84 83% 131.8°
2044-03-18 Fri 35 — unknown 20:05–21:30 (good, 1.42 h) 42.9° 18:10 8.79 75% 139.1°
2044-03-19 Sat 32 — unknown 20:10–21:25 (good, 1.25 h) 42.9° 18:05 8.74 66% 144.1°
2044-03-20 Sun 31 — unknown 20:10–21:20 (good, 1.17 h) 42.9° 18:05 8.69 57% 146.1°
2044-03-21 Mon 29 — unknown 20:10–21:20 (good, 1.17 h) 42.9° 18:00 8.64 48% 144.5°
2044-03-22 Tue 28 — unknown 20:10–21:15 (good, 1.08 h) 42.9° 17:55 8.58 38% 139.7°
2044-03-23 Wed 26 — unknown 20:15–21:10 (good, 0.92 h) 42.9° 17:50 8.53 29% 132.7°
2044-03-24 Thu 25 — unknown 20:15–21:05 (good, 0.83 h) 42.9° 17:45 8.48 21% 124.1°
2044-03-25 Fri 23 — unknown 20:15–21:05 (good, 0.83 h) 42.9° 17:45 8.43 13% 114.4°
2044-03-26 Sat 22 — unknown 20:15–21:00 (good, 0.75 h) 42.9° 17:40 8.37 7% 104.0°
2044-03-27 Sun 19 — unknown 21:20–21:55 (good, 0.58 h) 42.9° 18:35 8.32 3% 93.1°
2044-03-28 Mon 17 — unknown 21:20–21:50 (good, 0.5 h) 42.9° 18:30 8.27 0% 81.8°
2044-03-29 Tue 16 — unknown 21:20–21:45 (good, 0.42 h) 42.9° 18:30 8.21 0% 70.4°
2044-03-30 Wed 13 — unknown 21:25–21:45 (good, 0.33 h) 42.9° 18:25 8.16 3% 59.3°
2044-03-31 Thu 11 — unknown 21:25–21:35 (good, 0.17 h) 42.9° 18:20 8.1 8% 48.9°
2044-04-01 Fri 9 — unknown 20:50–22:05 (marginal, 1.25 h) 42.9° 18:15 8.05 16% 40.3°
2044-04-02 Sat 6 — unknown 21:25–22:00 (marginal, 0.58 h) 42.9° 18:10 7.99 25% 34.9°
2044-04-03 Sun 4 — unknown 21:30–22:00 (marginal, 0.5 h) 42.9° 18:10 7.94 36% 34.3°
2044-04-04 Mon 3 — unknown 21:30–21:50 (marginal, 0.33 h) 42.9° 18:05 7.88 47% 38.6°
2044-04-05 Tue 2 — unknown 21:30–21:35 (marginal, 0.08 h) 42.9° 18:00 7.83 59% 46.3°
2044-04-06 Wed 1 — unknown — 42.9° 17:55 7.77 70% 55.9°
2044-04-07 Thu 1 — unknown — 42.9° 17:50 7.71 79% 66.4°
2044-04-08 Fri 1 — unknown — 42.9° 17:50 7.66 87% 77.4°
2044-04-09 Sat 1 — unknown — 42.9° 17:45 7.6 94% 88.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-03-11&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.