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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 Vega: 05-08 (100), 05-09 (100), 05-10 (100), 05-11 (100), 05-12 (100) — by astronomy; check the weather when the night is within four days.
2026-05-02astronomy score per night — click a bar for that night2026-05-31
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-05-02 Sat 66 0 0 — 87.1° 05:15 6.31 98% 76.7°
2026-05-03 Sun 66 66 44 02:00–04:30 (good, 2.5 h) 87.1° 05:10 6.25 95% 72.7°
2026-05-04 Mon 76 24 18 03:00–04:25 (marginal, 1.42 h) 87.1° 05:05 6.19 91% 69.5°
2026-05-05 Tue 86 100 86 23:10–04:25 (good, 5.25 h) 87.1° 05:05 6.13 84% 67.1°
2026-05-06 Wed 92 98 90 23:05–04:20 (good, 5.25 h) 87.1° 05:00 6.08 77% 65.8°
2026-05-07 Thu 97 36 35 23:05–01:00 (good, 1.92 h) 87.1° 04:55 6.02 69% 65.5°
2026-05-08 Fri 100 16 16 02:00–04:00 (marginal, 2.0 h) 87.1° 04:50 5.96 59% 66.4°
2026-05-09 Sat 100 81 81 00:00–04:00 (good, 4.0 h) 87.1° 04:45 5.91 50% 68.4°
2026-05-10 Sun 100 42 42 02:00–03:00 (good, 1.0 h) 87.1° 04:45 5.85 40% 71.5°
2026-05-11 Mon 100 27 27 22:50–00:00 (good, 1.17 h) 87.1° 04:40 5.79 30% 75.6°
2026-05-12 Tue 100 93 93 23:00–04:10 (good, 5.17 h) 87.1° 04:35 5.74 20% 80.6°
2026-05-13 Wed 100 2 2 — 87.1° 04:30 5.68 12% 86.2°
2026-05-14 Thu 100 70 70 22:45–02:00 (good, 3.25 h) 87.1° 04:30 5.63 5% 92.2°
2026-05-15 Fri 100 68 68 22:30–02:00 (good, 3.5 h) 87.1° 04:25 5.58 1% 98.2°
2026-05-16 Sat 100 73 73 00:00–04:05 (good, 4.08 h) 87.1° 04:20 5.52 0% 103.9°
2026-05-17 Sun 100 2 2 — 87.1° 04:15 5.47 2% 108.7°
2026-05-18 Mon 100 3 3 — 87.1° 04:10 5.42 7% 112.3°
2026-05-19 Tue 100 0 0 — 87.1° 04:10 5.37 14% 114.3°
2026-05-20 Wed 100 74 74 22:40–04:00 (good, 5.33 h) 87.1° 04:05 5.32 23% 114.6°
2026-05-21 Thu 100 13 13 22:40–00:00 (marginal, 1.33 h) 87.1° 04:00 5.27 33% 113.2°
2026-05-22 Fri 100 6 6 — 87.1° 03:55 5.22 44% 110.5°
2026-05-23 Sat 100 46 46 01:00–02:00 (good, 1.0 h) 87.1° 03:50 5.17 55% 106.8°
2026-05-24 Sun 100 81 81 01:00–03:55 (good, 2.92 h) 87.1° 03:50 5.13 65% 102.4°
2026-05-25 Mon 100 40 40 01:00–03:00 (marginal, 2.0 h) 87.1° 03:45 5.08 74% 97.5°
2026-05-26 Tue 100 80 80 00:00–03:00 (good, 3.0 h) 87.1° 03:40 5.04 83% 92.4°
2026-05-27 Wed 100 78 78 23:05–01:00 (good, 1.92 h) 87.1° 03:35 4.99 89% 87.3°
2026-05-28 Thu 79 99 78 23:15–03:50 (good, 4.58 h) 87.1° 03:35 4.95 94% 82.4°
2026-05-29 Fri 75 91 68 01:00–03:50 (good, 2.83 h) 87.1° 03:30 4.91 98% 77.8°
2026-05-30 Sat 68 67 45 01:00–03:45 (marginal, 2.75 h) 87.1° 03:25 4.87 100% 73.6°
2026-05-31 Sun 65 95 61 00:00–03:45 (good, 3.75 h) 87.1° 03:20 4.83 100% 70.2°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-05-02&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.