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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 North America Nebula: 04-29 (80), 04-27 (78), 04-28 (78), 04-26 (76), 04-24 (75) — by astronomy; check the weather when the night is within four days.
2025-03-31astronomy score per night — click a bar for that night2025-04-29
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-03-31 Mon 52 0 0 — 87.3° 09:40 8.12 9% 74.4°
2025-04-01 Tue 53 0 0 — 87.2° 09:35 8.07 17% 81.6°
2025-04-02 Wed 53 0 0 — 87.2° 09:35 8.01 27% 89.0°
2025-04-03 Thu 54 0 0 — 87.3° 09:30 7.96 37% 96.2°
2025-04-04 Fri 55 0 0 — 87.3° 09:25 7.9 48% 103.0°
2025-04-05 Sat 54 79 43 04:00–05:20 (good, 1.33 h) 87.2° 09:20 7.85 59% 109.0°
2025-04-06 Sun 54 0 0 — 87.2° 09:20 7.79 69% 114.0°
2025-04-07 Mon 54 6 3 — 87.3° 09:15 7.74 78% 117.9°
2025-04-08 Tue 50 86 43 03:20–05:15 (good, 1.92 h) 87.3° 09:10 7.68 85% 120.3°
2025-04-09 Wed 51 93 48 03:25–05:15 (good, 1.83 h) 87.3° 09:05 7.62 92% 121.2°
2025-04-10 Thu 49 34 17 05:00–05:10 (good, 0.17 h) 87.2° 09:00 7.57 96% 120.6°
2025-04-11 Fri 49 3 1 — 87.2° 09:00 7.51 99% 118.5°
2025-04-12 Sat 47 0 0 — 87.3° 08:55 7.45 100% 115.2°
2025-04-13 Sun 45 0 0 — 87.3° 08:50 7.39 99% 110.9°
2025-04-14 Mon 44 10 5 02:55–03:00 (marginal, 0.08 h) 87.3° 08:45 7.34 97% 105.7°
2025-04-15 Tue 43 79 34 02:05–05:00 (marginal, 2.92 h) 87.2° 08:40 7.28 92% 100.1°
2025-04-16 Wed 42 96 40 03:00–05:00 (good, 2.0 h) 87.2° 08:40 7.22 87% 94.0°
2025-04-17 Thu 43 0 0 — 87.3° 08:35 7.16 79% 87.8°
2025-04-18 Fri 45 0 0 — 87.3° 08:30 7.11 71% 81.5°
2025-04-19 Sat 50 42 21 02:25–02:45 (good, 0.33 h) 87.3° 08:25 7.05 62% 75.4°
2025-04-20 Sun 56 83 46 03:00–04:50 (good, 1.83 h) 87.2° 08:25 6.99 52% 69.8°
2025-04-21 Mon 63 75 47 03:00–04:00 (good, 1.0 h) 87.3° 08:20 6.93 41% 64.9°
2025-04-22 Tue 68 58 39 04:00–04:50 (good, 0.83 h) 87.3° 08:15 6.87 30% 61.1°
2025-04-23 Wed 72 72 51 03:00–04:00 (good, 1.0 h) 87.3° 08:10 6.81 21% 59.0°
2025-04-24 Thu 75 91 68 02:00–04:45 (good, 2.75 h) 87.2° 08:05 6.76 12% 58.9°
2025-04-25 Fri 74 100 74 01:50–04:40 (good, 2.83 h) 87.2° 08:05 6.7 5% 61.1°
2025-04-26 Sat 76 44 33 02:00–04:40 (marginal, 2.67 h) 87.3° 08:00 6.64 1% 65.4°
2025-04-27 Sun 78 0 0 — 87.3° 07:55 6.58 0% 71.4°
2025-04-28 Mon 78 100 78 01:35–04:35 (good, 3.0 h) 87.3° 07:50 6.52 2% 78.4°
2025-04-29 Tue 80 100 80 01:30–04:35 (good, 3.08 h) 87.2° 07:45 6.47 7% 86.0°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-03-31&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.