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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: 03-19 (33), 03-20 (31), 03-21 (28), 03-22 (23), 03-23 (18) — by astronomy; check the weather when the night is within four days.
2026-03-19astronomy score per night — click a bar for that night2026-04-17
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-03-19 Thu 33 0 0 — 42.9° 18:10 8.77 1% 75.8°
2026-03-20 Fri 31 0 0 — 42.9° 18:05 8.72 5% 64.3°
2026-03-21 Sat 28 0 0 — 42.9° 18:00 8.67 11% 53.4°
2026-03-22 Sun 23 0 0 — 42.9° 17:55 8.62 19% 43.7°
2026-03-23 Mon 18 0 0 — 42.9° 17:55 8.57 29% 36.7°
2026-03-24 Tue 13 0 0 — 42.9° 17:50 8.51 40% 33.8°
2026-03-25 Wed 9 77 7 20:15–21:00 (marginal, 0.75 h) 42.9° 17:45 8.46 52% 35.9°
2026-03-26 Thu 7 90 6 20:15–21:10 (marginal, 0.92 h) 42.9° 17:40 8.41 63% 42.2°
2026-03-27 Fri 6 0 0 — 42.9° 17:35 8.35 73% 51.0°
2026-03-28 Sat 6 35 2 — 42.9° 17:35 8.3 82% 61.0°
2026-03-29 Sun 6 0 0 — 42.9° 18:30 8.25 90% 71.6°
2026-03-30 Mon 6 3 0 — 42.9° 18:25 8.19 95% 82.5°
2026-03-31 Tue 7 10 1 — 42.9° 18:20 8.14 99% 93.3°
2026-04-01 Wed 8 0 0 — 42.9° 18:20 8.08 100% 103.8°
2026-04-02 Thu 8 0 0 — 42.9° 18:15 8.03 99% 114.0°
2026-04-03 Fri 8 0 0 — 42.9° 18:10 7.97 96% 123.5°
2026-04-04 Sat 7 0 0 — 42.9° 18:05 7.92 92% 132.1°
2026-04-05 Sun 6 89 5 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.86 86% 139.3°
2026-04-06 Mon 5 80 4 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.8 79% 144.4°
2026-04-07 Tue 3 19 1 — 42.9° 17:55 7.75 71% 146.3°
2026-04-08 Wed 3 100 3 21:00–21:10 (marginal, 0.17 h) 42.9° 17:50 7.69 62% 144.7°
2026-04-09 Thu 2 15 0 — 42.9° 17:45 7.64 53% 139.9°
2026-04-10 Fri 1 0 0 — 42.9° 17:40 7.58 43% 132.8°
2026-04-11 Sat 1 49 0 — 42.9° 17:40 7.52 33% 124.1°
2026-04-12 Sun 1 15 0 — 42.9° 17:35 7.47 24% 114.3°
2026-04-13 Mon 1 0 0 — 42.9° 17:30 7.41 16% 103.6°
2026-04-14 Tue 1 0 0 — 42.9° 17:25 7.35 9% 92.4°
2026-04-15 Wed 0 0 0 — 42.9° 17:25 7.29 3% 80.7°
2026-04-16 Thu 0 0 0 — 42.9° 17:20 7.24 0% 69.0°
2026-04-17 Fri 0 100 0 — 42.9° 17:15 7.18 0% 57.5°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-03-19&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.