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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 V1057 Cyg: 05-17 (100), 05-18 (100), 05-19 (100), 05-20 (100), 05-21 (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 54 0 0 — 87.3° 07:35 6.31 98% 101.4°
2026-05-03 Sun 52 93 48 02:00–04:30 (good, 2.5 h) 87.3° 07:35 6.25 95% 95.1°
2026-05-04 Mon 50 38 19 04:00–04:25 (good, 0.42 h) 87.3° 07:30 6.19 91% 88.6°
2026-05-05 Tue 50 100 50 01:35–04:25 (good, 2.83 h) 87.3° 07:25 6.13 84% 82.2°
2026-05-06 Wed 53 98 52 01:30–04:20 (good, 2.83 h) 87.3° 07:20 6.08 77% 76.0°
2026-05-07 Thu 62 9 6 00:25–01:00 (marginal, 0.58 h) 87.3° 07:15 6.02 69% 70.2°
2026-05-08 Fri 68 23 16 02:00–04:00 (marginal, 2.0 h) 87.3° 07:15 5.96 59% 65.1°
2026-05-09 Sat 74 82 61 01:00–04:00 (good, 3.0 h) 87.3° 07:10 5.91 50% 60.9°
2026-05-10 Sun 80 45 36 02:00–03:00 (good, 1.0 h) 87.3° 07:05 5.85 40% 58.0°
2026-05-11 Mon 86 7 6 00:40–01:00 (marginal, 0.33 h) 87.3° 07:00 5.79 30% 56.8°
2026-05-12 Tue 90 96 86 00:45–04:10 (good, 3.42 h) 87.3° 06:55 5.74 20% 57.6°
2026-05-13 Wed 94 0 0 — 87.3° 06:55 5.68 12% 60.5°
2026-05-14 Thu 97 59 57 00:35–02:00 (good, 1.42 h) 87.3° 06:50 5.63 5% 65.3°
2026-05-15 Fri 97 57 55 00:50–02:00 (good, 1.17 h) 87.3° 06:45 5.58 1% 71.8°
2026-05-16 Sat 99 84 83 01:00–04:05 (good, 3.08 h) 87.3° 06:40 5.52 0% 79.4°
2026-05-17 Sun 100 0 0 — 87.3° 06:40 5.47 2% 87.5°
2026-05-18 Mon 100 5 5 — 87.3° 06:35 5.42 7% 95.8°
2026-05-19 Tue 100 0 0 — 87.3° 06:30 5.37 14% 103.7°
2026-05-20 Wed 100 68 68 01:15–02:00 (good, 0.75 h) 87.3° 06:25 5.32 23% 110.7°
2026-05-21 Thu 100 4 4 — 87.3° 06:20 5.27 33% 116.5°
2026-05-22 Fri 100 5 5 — 87.3° 06:20 5.22 44% 120.6°
2026-05-23 Sat 100 45 45 01:00–02:00 (good, 1.0 h) 87.3° 06:15 5.17 55% 122.9°
2026-05-24 Sun 100 85 85 01:00–03:55 (good, 2.92 h) 87.3° 06:10 5.13 65% 123.2°
2026-05-25 Mon 100 43 43 02:40–03:00 (good, 0.33 h) 87.3° 06:05 5.08 74% 121.7°
2026-05-26 Tue 100 80 80 00:15–03:00 (good, 2.75 h) 87.3° 06:00 5.04 83% 118.6°
2026-05-27 Wed 100 77 77 03:00–03:50 (good, 0.83 h) 87.3° 06:00 4.99 89% 114.2°
2026-05-28 Thu 86 99 85 00:00–03:50 (good, 3.83 h) 87.3° 05:55 4.95 94% 108.9°
2026-05-29 Fri 79 92 72 01:00–03:50 (good, 2.83 h) 87.3° 05:50 4.91 98% 103.0°
2026-05-30 Sat 73 65 48 02:00–03:45 (good, 1.75 h) 87.3° 05:45 4.87 100% 96.7°
2026-05-31 Sun 67 96 64 00:40–03:45 (good, 3.08 h) 87.3° 05:40 4.83 100% 90.2°

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.