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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: 12-23 (11), 12-24 (10), 12-25 (9), 12-26 (9), 12-29 (9) — by astronomy; check the weather when the night is within four days.
2028-12-23astronomy score per night — click a bar for that night2029-01-21
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2028-12-23 Sat 11 — unknown 18:40–18:45 (good, 0.08 h) 71.1° 14:15 11.5 50% 60.5°
2028-12-24 Sun 10 — unknown 18:40–19:40 (marginal, 1.0 h) 71.1° 14:10 11.5 60% 68.8°
2028-12-25 Mon 9 — unknown 18:40–19:35 (marginal, 0.92 h) 71.1° 14:05 11.5 69% 77.7°
2028-12-26 Tue 9 — unknown 18:40–19:30 (marginal, 0.83 h) 71.1° 14:00 11.49 77% 86.9°
2028-12-27 Wed 8 — unknown 18:40–19:30 (marginal, 0.83 h) 71.1° 13:55 11.49 85% 96.4°
2028-12-28 Thu 8 — unknown 18:05–19:25 (marginal, 1.33 h) 71.1° 13:55 11.48 92% 106.0°
2028-12-29 Fri 9 — unknown 18:10–19:25 (marginal, 1.25 h) 71.1° 13:50 11.47 96% 115.4°
2028-12-30 Sat 8 — unknown 18:10–19:20 (marginal, 1.17 h) 71.1° 13:45 11.47 99% 124.4°
2028-12-31 Sun 7 — unknown 18:45–19:15 (marginal, 0.5 h) 71.1° 13:40 11.46 100% 132.2°
2029-01-01 Mon 6 — unknown 18:45–19:10 (marginal, 0.42 h) 71.1° 13:35 11.45 98% 137.8°
2029-01-02 Tue 6 — unknown 18:10–18:40 (marginal, 0.5 h) 71.1° 13:35 11.44 94% 140.2°
2029-01-03 Wed 5 — unknown 18:45–19:05 (marginal, 0.33 h) 71.1° 13:30 11.42 87% 138.4°
2029-01-04 Thu 4 — unknown 18:45–19:00 (marginal, 0.25 h) 71.1° 13:25 11.41 78% 133.0°
2029-01-05 Fri 3 — unknown 18:15–18:30 (marginal, 0.25 h) 71.1° 13:20 11.4 68% 125.0°
2029-01-06 Sat 2 — unknown 18:15–18:25 (marginal, 0.17 h) 71.1° 13:20 11.38 57% 115.6°
2029-01-07 Sun 2 — unknown 18:15–18:20 (marginal, 0.08 h) 71.1° 13:15 11.37 46% 105.3°
2029-01-08 Mon 1 — unknown — 71.1° 13:10 11.35 35% 94.6°
2029-01-09 Tue 1 — unknown — 71.1° 13:05 11.34 24% 84.0°
2029-01-10 Wed 1 — unknown — 71.1° 13:00 11.32 16% 73.6°
2029-01-11 Thu 1 — unknown — 71.1° 13:00 11.3 8% 63.7°
2029-01-12 Fri 0 — unknown — 71.1° 12:55 11.28 4% 54.8°
2029-01-13 Sat 0 — unknown — 71.1° 12:50 11.26 1% 47.4°
2029-01-14 Sun 0 — unknown — 71.1° 12:45 11.24 0% 42.2°
2029-01-15 Mon 0 — unknown — 71.1° 12:40 11.22 2% 39.9°
2029-01-16 Tue 0 — unknown — 71.1° 12:40 11.2 5% 40.8°
2029-01-17 Wed 0 — unknown — 71.1° 12:35 11.17 10% 44.7°
2029-01-18 Thu 0 — unknown — 71.1° 12:30 11.15 17% 50.6°
2029-01-19 Fri 0 — unknown — 71.1° 12:25 11.13 24% 57.9°
2029-01-20 Sat 0 — unknown — 71.1° 12:25 11.1 33% 66.0°
2029-01-21 Sun 0 — unknown — 71.1° 12:20 11.08 42% 74.6°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-12-23&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.