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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: 02-11 (7), 02-12 (7), 02-13 (7), 02-10 (6), 02-09 (5) — by astronomy; check the weather when the night is within four days.
2041-01-15astronomy score per night — click a bar for that night2041-02-13
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2041-01-15 Tue 0 — unknown — 71.1° 12:40 11.22 98% 127.7°
2041-01-16 Wed 0 — unknown — 71.1° 12:40 11.2 100% 131.3°
2041-01-17 Thu 0 — unknown — 71.1° 12:35 11.17 100% 132.9°
2041-01-18 Fri 0 — unknown — 71.1° 12:30 11.15 97% 132.2°
2041-01-19 Sat 0 — unknown — 71.1° 12:25 11.12 94% 129.4°
2041-01-20 Sun 0 — unknown — 71.1° 12:25 11.1 88% 124.8°
2041-01-21 Mon 0 — unknown — 71.1° 12:20 11.07 82% 118.8°
2041-01-22 Tue 0 — unknown — 71.1° 12:15 11.05 74% 111.7°
2041-01-23 Wed 0 — unknown — 71.1° 12:10 11.02 65% 103.9°
2041-01-24 Thu 0 — unknown — 71.1° 12:05 10.99 55% 95.6°
2041-01-25 Fri 0 — unknown — 71.1° 12:00 10.96 45% 86.9°
2041-01-26 Sat 0 — unknown — 71.1° 11:55 10.93 34% 78.0°
2041-01-27 Sun 0 — unknown — 71.1° 11:50 10.9 24% 69.2°
2041-01-28 Mon 1 — unknown — 71.1° 11:45 10.87 15% 60.8°
2041-01-29 Tue 1 — unknown — 71.1° 11:45 10.84 8% 53.7°
2041-01-30 Wed 1 — unknown — 71.1° 11:40 10.81 3% 48.8°
2041-01-31 Thu 1 — unknown — 71.1° 11:35 10.78 0% 47.1°
2041-02-01 Fri 1 — unknown — 71.1° 11:30 10.75 1% 49.1°
2041-02-02 Sat 1 — unknown 06:25–06:30 (marginal, 0.08 h) 71.1° 11:30 10.71 5% 54.3°
2041-02-03 Sun 2 — unknown 06:25–06:30 (marginal, 0.08 h) 71.1° 11:25 10.68 11% 61.7°
2041-02-04 Mon 3 — unknown 06:20–06:30 (marginal, 0.17 h) 71.1° 11:20 10.64 19% 70.4°
2041-02-05 Tue 3 — unknown 06:15–06:30 (marginal, 0.25 h) 71.1° 11:15 10.61 29% 79.5°
2041-02-06 Wed 3 — unknown 06:10–06:25 (marginal, 0.25 h) 71.1° 11:10 10.57 39% 88.7°
2041-02-07 Thu 4 — unknown 05:40–05:55 (marginal, 0.25 h) 71.1° 11:10 10.54 50% 97.6°
2041-02-08 Fri 4 — unknown 05:35–05:50 (marginal, 0.25 h) 71.1° 11:05 10.5 60% 106.1°
2041-02-09 Sat 5 — unknown 05:30–05:50 (marginal, 0.33 h) 71.1° 11:00 10.46 69% 113.9°
2041-02-10 Sun 6 — unknown 05:55–06:25 (marginal, 0.5 h) 71.1° 10:55 10.43 78% 120.8°
2041-02-11 Mon 7 — unknown 05:25–06:20 (marginal, 0.92 h) 71.1° 10:50 10.39 85% 126.4°
2041-02-12 Tue 7 — unknown 05:20–05:50 (marginal, 0.5 h) 71.1° 10:50 10.35 91% 130.5°
2041-02-13 Wed 7 — unknown 05:15–05:45 (marginal, 0.5 h) 71.1° 10:45 10.31 96% 132.7°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-01-15&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.