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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: 03-27 (7), 04-01 (6), 04-02 (6), 04-03 (6), 03-28 (5) — by astronomy; check the weather when the night is within four days.
2034-03-27astronomy score per night — click a bar for that night2034-04-25
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2034-03-27 Mon 7 — unknown 21:20–22:10 (marginal, 0.83 h) 42.9° 18:35 8.35 60% 33.6°
2034-03-28 Tue 5 — unknown 21:20–22:00 (marginal, 0.67 h) 42.9° 18:35 8.3 70% 43.7°
2034-03-29 Wed 5 — unknown 21:20–21:55 (marginal, 0.58 h) 42.9° 18:30 8.24 79% 54.6°
2034-03-30 Thu 5 — unknown 21:20–21:55 (marginal, 0.58 h) 42.9° 18:25 8.19 86% 65.8°
2034-03-31 Fri 5 — unknown 21:25–22:00 (marginal, 0.58 h) 42.9° 18:20 8.13 92% 77.1°
2034-04-01 Sat 6 — unknown 21:25–22:05 (marginal, 0.67 h) 42.9° 18:20 8.08 97% 88.3°
2034-04-02 Sun 6 — unknown 21:25–22:05 (marginal, 0.67 h) 42.9° 18:15 8.02 99% 99.4°
2034-04-03 Mon 6 — unknown 21:25–22:00 (marginal, 0.58 h) 42.9° 18:10 7.97 100% 110.3°
2034-04-04 Tue 5 — unknown 21:30–21:55 (marginal, 0.42 h) 42.9° 18:05 7.91 99% 121.0°
2034-04-05 Wed 5 — unknown 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.86 96% 131.3°
2034-04-06 Thu 5 — unknown 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.8 91% 141.0°
2034-04-07 Fri 3 — unknown 21:00–21:15 (marginal, 0.25 h) 42.9° 17:55 7.75 85% 149.4°
2034-04-08 Sat 3 — unknown 21:00–21:10 (marginal, 0.17 h) 42.9° 17:50 7.69 78% 155.2°
2034-04-09 Sun 2 — unknown 21:00–21:05 (marginal, 0.08 h) 42.9° 17:45 7.63 70% 156.3°
2034-04-10 Mon 2 — unknown — 42.9° 17:40 7.58 60% 151.9°
2034-04-11 Tue 1 — unknown — 42.9° 17:40 7.52 50% 143.8°
2034-04-12 Wed 1 — unknown — 42.9° 17:35 7.46 40% 133.6°
2034-04-13 Thu 1 — unknown — 42.9° 17:30 7.4 30% 122.2°
2034-04-14 Fri 1 — unknown — 42.9° 17:25 7.35 20% 109.9°
2034-04-15 Sat 0 — unknown — 42.9° 17:25 7.29 12% 96.9°
2034-04-16 Sun 0 — unknown — 42.9° 17:20 7.23 5% 83.4°
2034-04-17 Mon 0 — unknown — 42.9° 17:15 7.17 1% 69.8°
2034-04-18 Tue 0 — unknown — 42.9° 17:10 7.12 0% 56.2°
2034-04-19 Wed 0 — unknown — 42.9° 17:05 7.06 2% 43.2°
2034-04-20 Thu 0 — unknown — 42.9° 17:05 7.0 7% 32.0°
2034-04-21 Fri 0 — unknown — 42.9° 17:00 6.94 14% 24.6°
2034-04-22 Sat 0 — unknown — 42.9° 16:55 6.88 23% 24.5°
2034-04-23 Sun 0 — unknown — 42.9° 16:50 6.83 33% 31.1°
2034-04-24 Mon 0 — unknown — 42.9° 16:45 6.77 44% 40.9°
2034-04-25 Tue 0 — unknown — 42.9° 16:45 6.71 55% 51.8°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2034-03-27&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.