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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 HD 189733: 06-09 (100), 06-10 (100), 06-11 (100), 06-12 (100), 06-13 (100) — by astronomy; check the weather when the night is within four days.
2026-06-09astronomy score per night — click a bar for that night2026-07-08
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-06-09 Tue 100 98 98 23:10–03:40 (good, 4.5 h) 71.1° 04:10 4.56 34% 65.5°
2026-06-10 Wed 100 96 96 23:15–03:40 (good, 4.42 h) 71.1° 04:05 4.53 24% 74.8°
2026-06-11 Thu 100 48 48 23:20–02:00 (good, 2.67 h) 71.1° 04:00 4.51 15% 84.9°
2026-06-12 Fri 100 0 0 — 71.1° 03:55 4.49 7% 95.5°
2026-06-13 Sat 100 94 94 23:10–03:40 (good, 4.5 h) 71.1° 03:55 4.48 2% 106.1°
2026-06-14 Sun 100 91 91 23:10–03:40 (good, 4.5 h) 71.1° 03:50 4.46 0% 116.2°
2026-06-15 Mon 100 64 64 02:00–03:40 (good, 1.67 h) 71.1° 03:45 4.45 1% 125.2°
2026-06-16 Tue 100 0 0 — 71.1° 03:40 4.44 5% 131.9°
2026-06-17 Wed 100 35 35 03:00–03:40 (good, 0.67 h) 71.1° 03:40 4.43 12% 135.6°
2026-06-18 Thu 100 74 74 23:10–03:40 (good, 4.5 h) 71.1° 03:35 4.43 20% 135.5°
2026-06-19 Fri 100 93 93 23:10–03:40 (good, 4.5 h) 71.1° 03:30 4.42 30% 132.1°
2026-06-20 Sat 100 98 98 23:15–03:40 (good, 4.42 h) 71.1° 03:25 4.42 40% 126.3°
2026-06-21 Sun 100 99 99 23:15–03:40 (good, 4.42 h) 71.1° 03:20 4.42 50% 119.0°
2026-06-22 Mon 100 89 89 23:15–03:40 (good, 4.42 h) 71.1° 03:20 4.42 60% 110.9°
2026-06-23 Tue 100 60 60 01:00–03:40 (good, 2.67 h) 71.1° 03:15 4.43 70% 102.4°
2026-06-24 Wed 100 87 87 23:15–03:40 (good, 4.42 h) 71.1° 03:10 4.43 78% 93.7°
2026-06-25 Thu 100 89 89 23:35–03:40 (good, 4.08 h) 71.1° 03:05 4.44 86% 85.1°
2026-06-26 Fri 100 96 96 00:15–03:40 (good, 3.42 h) 71.1° 03:00 4.45 92% 76.7°
2026-06-27 Sat 69 66 45 00:30–02:00 (good, 1.5 h) 71.1° 03:00 4.47 96% 68.6°
2026-06-28 Sun 58 100 58 00:40–03:40 (good, 3.0 h) 71.1° 02:55 4.48 99% 61.0°
2026-06-29 Mon 49 89 44 23:10–03:40 (marginal, 4.5 h) 71.1° 02:50 4.5 100% 54.3°
2026-06-30 Tue 43 96 41 23:10–03:45 (marginal, 4.58 h) 71.1° 02:45 4.52 99% 48.8°
2026-07-01 Wed 43 27 11 23:10–00:00 (marginal, 0.83 h) 71.1° 02:45 4.54 96% 45.2°
2026-07-02 Thu 47 74 35 23:10–03:45 (marginal, 4.58 h) 71.1° 02:40 4.56 92% 43.9°
2026-07-03 Fri 78 31 24 02:00–03:00 (marginal, 1.0 h) 71.1° 02:35 4.58 86% 45.3°
2026-07-04 Sat 89 72 64 01:00–01:15 (good, 0.25 h) 71.1° 02:30 4.61 78% 49.3°
2026-07-05 Sun 96 89 86 23:10–03:00 (good, 3.83 h) 71.1° 02:25 4.64 70% 55.3°
2026-07-06 Mon 99 97 96 23:10–03:50 (good, 4.67 h) 71.1° 02:25 4.67 59% 62.9°
2026-07-07 Tue 100 96 96 23:10–03:50 (good, 4.67 h) 71.1° 02:20 4.7 49% 71.7°
2026-07-08 Wed 100 0 0 — 71.1° 02:15 4.73 38% 81.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-06-09&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.