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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: 04-15 (100), 04-16 (100), 04-17 (100), 04-18 (100), 04-19 (100) — by astronomy; check the weather when the night is within four days.
2026-04-15astronomy score per night — click a bar for that night2026-05-14
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-04-15 Wed 100 0 0 — 87.1° 06:20 7.29 3% 83.0°
2026-04-16 Thu 100 22 22 04:00–05:35 (marginal, 1.58 h) 87.1° 06:20 7.24 0% 88.9°
2026-04-17 Fri 100 95 95 00:25–05:00 (good, 4.58 h) 87.1° 06:15 7.18 0% 94.9°
2026-04-18 Sat 100 92 92 00:40–04:55 (good, 4.25 h) 87.1° 06:10 7.12 3% 100.7°
2026-04-19 Sun 100 83 83 01:00–04:55 (good, 3.92 h) 87.1° 06:05 7.06 9% 105.9°
2026-04-20 Mon 100 81 81 01:00–04:50 (good, 3.83 h) 87.1° 06:00 7.0 16% 110.1°
2026-04-21 Tue 100 0 0 — 87.1° 06:00 6.95 26% 113.0°
2026-04-22 Wed 100 0 0 — 87.1° 05:55 6.89 37% 114.3°
2026-04-23 Thu 100 74 74 00:05–04:00 (good, 3.92 h) 87.1° 05:50 6.83 48% 114.1°
2026-04-24 Fri 100 82 82 01:00–04:45 (good, 3.75 h) 87.1° 05:45 6.77 59% 112.4°
2026-04-25 Sat 100 91 91 00:25–04:45 (good, 4.33 h) 87.1° 05:40 6.71 69% 109.5°
2026-04-26 Sun 100 100 100 00:05–04:40 (good, 4.58 h) 87.1° 05:40 6.65 78% 105.6°
2026-04-27 Mon 100 72 72 01:00–03:00 (good, 2.0 h) 87.1° 05:35 6.6 86% 101.1°
2026-04-28 Tue 84 64 54 04:00–04:35 (good, 0.58 h) 87.1° 05:30 6.54 92% 96.2°
2026-04-29 Wed 80 38 31 23:20–02:00 (marginal, 2.67 h) 87.1° 05:25 6.48 97% 91.1°
2026-04-30 Thu 74 0 0 — 87.1° 05:25 6.42 99% 86.0°
2026-05-01 Fri 68 54 36 02:00–04:00 (good, 2.0 h) 87.1° 05:20 6.36 100% 81.1°
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°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-04-15&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.