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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: 04-21 (71), 04-22 (71), 04-23 (71), 04-20 (69), 04-18 (68) — by astronomy; check the weather when the night is within four days.
2026-03-25astronomy score per night — click a bar for that night2026-04-23
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-03-25 Wed 47 76 36 02:55–04:00 (good, 1.08 h) 87.3° 09:05 8.46 52% 100.4°
2026-03-26 Thu 46 0 0 — 87.3° 09:00 8.41 63% 107.4°
2026-03-27 Fri 46 11 5 02:40–03:00 (marginal, 0.33 h) 87.3° 09:00 8.35 73% 113.5°
2026-03-28 Sat 45 0 0 — 87.3° 09:55 8.3 82% 118.3°
2026-03-29 Sun 42 0 0 — 87.3° 09:50 8.25 90% 121.6°
2026-03-30 Mon 42 0 0 — 87.3° 09:45 8.19 95% 123.0°
2026-03-31 Tue 41 0 0 — 87.3° 09:40 8.14 99% 122.4°
2026-04-01 Wed 42 0 0 — 87.3° 09:40 8.08 100% 120.1°
2026-04-02 Thu 41 0 0 — 87.3° 09:35 8.03 99% 116.3°
2026-04-03 Fri 39 0 0 — 87.3° 09:30 7.97 96% 111.4°
2026-04-04 Sat 39 13 5 — 87.3° 09:25 7.92 92% 105.8°
2026-04-05 Sun 37 89 33 04:00–05:20 (good, 1.33 h) 87.3° 09:25 7.86 86% 99.7°
2026-04-06 Mon 38 89 34 03:25–05:00 (good, 1.58 h) 87.3° 09:20 7.8 79% 93.3°
2026-04-07 Tue 39 68 27 05:00–05:20 (good, 0.33 h) 87.3° 09:15 7.75 71% 86.9°
2026-04-08 Wed 41 1 0 — 87.3° 09:10 7.69 62% 80.5°
2026-04-09 Thu 45 10 5 02:30–03:00 (marginal, 0.5 h) 87.3° 09:05 7.64 53% 74.4°
2026-04-10 Fri 50 0 0 — 87.3° 09:05 7.58 43% 68.7°
2026-04-11 Sat 55 3 2 — 87.3° 09:00 7.52 33% 63.8°
2026-04-12 Sun 60 0 0 — 87.3° 08:55 7.47 24% 59.9°
2026-04-13 Mon 62 0 0 — 87.3° 08:50 7.41 16% 57.5°
2026-04-14 Tue 64 21 13 02:35–03:00 (good, 0.42 h) 87.3° 08:45 7.35 9% 57.0°
2026-04-15 Wed 64 0 0 — 87.3° 08:45 7.29 3% 58.7°
2026-04-16 Thu 65 32 21 04:00–05:35 (marginal, 1.58 h) 87.3° 08:40 7.24 0% 62.4°
2026-04-17 Fri 67 95 64 02:25–05:00 (good, 2.58 h) 87.3° 08:35 7.18 0% 68.0°
2026-04-18 Sat 68 96 65 02:25–04:55 (good, 2.5 h) 87.3° 08:30 7.12 3% 74.9°
2026-04-19 Sun 68 90 61 02:15–04:55 (good, 2.67 h) 87.3° 08:30 7.06 9% 82.7°
2026-04-20 Mon 69 92 64 02:10–04:50 (good, 2.67 h) 87.3° 08:25 7.0 16% 90.7°
2026-04-21 Tue 71 0 0 — 87.3° 08:20 6.95 26% 98.6°
2026-04-22 Wed 71 0 0 — 87.3° 08:15 6.89 37% 105.9°
2026-04-23 Thu 71 61 43 02:10–04:00 (good, 1.83 h) 87.3° 08:10 6.83 48% 112.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-03-25&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.