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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: 03-21 (30), 03-22 (28), 03-23 (27), 03-24 (25), 03-20 (24) — by astronomy; check the weather when the night is within four days.
2030-03-14astronomy score per night — click a bar for that night2030-04-12
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2030-03-14 Thu 10 — unknown 20:00–21:45 (marginal, 1.75 h) 42.9° 18:30 9.02 74% 38.8°
2030-03-15 Fri 9 — unknown 20:05–21:40 (marginal, 1.58 h) 42.9° 18:25 8.97 83% 48.1°
2030-03-16 Sat 10 — unknown 20:05–21:40 (marginal, 1.58 h) 42.9° 18:20 8.92 90% 58.8°
2030-03-17 Sun 13 — unknown 20:05–21:45 (marginal, 1.67 h) 42.9° 18:15 8.87 96% 70.4°
2030-03-18 Mon 17 — unknown 20:05–21:55 (marginal, 1.83 h) 42.9° 18:15 8.82 99% 82.8°
2030-03-19 Tue 20 — unknown 20:10–21:00 (good, 0.83 h) 42.9° 18:10 8.77 100% 95.5°
2030-03-20 Wed 24 — unknown 20:10–21:05 (good, 0.92 h) 42.9° 18:05 8.72 98% 108.3°
2030-03-21 Thu 30 — unknown 20:10–21:10 (good, 1.0 h) 42.9° 18:00 8.67 93% 120.9°
2030-03-22 Fri 28 — unknown 20:10–21:15 (good, 1.08 h) 42.9° 17:55 8.62 86% 132.7°
2030-03-23 Sat 27 — unknown 20:15–21:10 (good, 0.92 h) 42.9° 17:55 8.56 77% 142.9°
2030-03-24 Sun 25 — unknown 20:15–21:10 (good, 0.92 h) 42.9° 17:50 8.51 66% 150.0°
2030-03-25 Mon 24 — unknown 20:15–21:05 (good, 0.83 h) 42.9° 17:45 8.46 55% 151.6°
2030-03-26 Tue 22 — unknown 20:15–21:00 (good, 0.75 h) 42.9° 17:40 8.41 44% 147.2°
2030-03-27 Wed 20 — unknown 20:20–20:55 (good, 0.58 h) 42.9° 17:35 8.35 34% 139.1°
2030-03-28 Thu 19 — unknown 20:20–20:55 (good, 0.58 h) 42.9° 17:35 8.3 24% 129.2°
2030-03-29 Fri 17 — unknown 20:20–20:50 (good, 0.5 h) 42.9° 17:30 8.24 16% 118.4°
2030-03-30 Sat 15 — unknown 20:20–20:45 (good, 0.42 h) 42.9° 17:25 8.19 9% 107.4°
2030-03-31 Sun 12 — unknown 21:25–21:40 (good, 0.25 h) 42.9° 18:20 8.14 4% 96.3°
2030-04-01 Mon 11 — unknown 21:25–21:35 (good, 0.17 h) 42.9° 18:20 8.08 1% 85.3°
2030-04-02 Tue 10 — unknown 21:25–21:35 (good, 0.17 h) 42.9° 18:15 8.03 0% 74.5°
2030-04-03 Wed 8 — unknown 21:25–21:30 (good, 0.08 h) 42.9° 18:10 7.97 1% 64.1°
2030-04-04 Thu 6 — unknown 21:30–21:55 (marginal, 0.42 h) 42.9° 18:05 7.91 4% 54.1°
2030-04-05 Fri 5 — unknown 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.86 8% 44.8°
2030-04-06 Sat 4 — unknown 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.8 14% 36.7°
2030-04-07 Sun 3 — unknown 21:35–21:45 (marginal, 0.17 h) 42.9° 17:55 7.75 21% 30.6°
2030-04-08 Mon 2 — unknown 21:35–21:40 (marginal, 0.08 h) 42.9° 17:50 7.69 29% 28.1°
2030-04-09 Tue 1 — unknown — 42.9° 17:45 7.63 38% 30.1°
2030-04-10 Wed 1 — unknown — 42.9° 17:40 7.58 48% 35.9°
2030-04-11 Thu 0 — unknown — 42.9° 17:40 7.52 58% 44.3°
2030-04-12 Fri 0 — unknown — 42.9° 17:35 7.46 68% 54.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-03-14&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.