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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: 12-26 (18), 12-27 (16), 12-28 (15), 12-29 (12), 12-30 (10) — by astronomy; check the weather when the night is within four days.
2046-12-26astronomy score per night — click a bar for that night2047-01-24
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2046-12-26 Wed 18 — unknown 18:40–19:10 (good, 0.5 h) 71.1° 14:05 11.5 0% 57.3°
2046-12-27 Thu 16 — unknown 18:40–19:05 (good, 0.42 h) 71.1° 14:00 11.49 0% 49.4°
2046-12-28 Fri 15 — unknown 18:40–19:00 (good, 0.33 h) 71.2° 13:55 11.48 3% 43.7°
2046-12-29 Sat 12 — unknown 18:40–18:55 (good, 0.25 h) 71.1° 13:50 11.48 7% 40.9°
2046-12-30 Sun 10 — unknown 18:40–18:50 (good, 0.17 h) 71.1° 13:45 11.47 13% 41.5°
2046-12-31 Mon 7 — unknown 18:45–19:15 (marginal, 0.5 h) 71.1° 13:45 11.46 20% 45.0°
2047-01-01 Tue 6 — unknown 18:45–19:15 (marginal, 0.5 h) 71.2° 13:40 11.45 29% 50.7°
2047-01-02 Wed 4 — unknown 18:45–19:10 (marginal, 0.42 h) 71.1° 13:35 11.44 38% 57.7°
2047-01-03 Thu 3 — unknown 18:45–19:05 (marginal, 0.33 h) 71.1° 13:30 11.43 47% 65.7°
2047-01-04 Fri 3 — unknown 18:45–19:00 (marginal, 0.25 h) 71.1° 13:30 11.42 57% 74.2°
2047-01-05 Sat 2 — unknown 18:45–18:55 (marginal, 0.17 h) 71.1° 13:25 11.4 66% 83.0°
2047-01-06 Sun 2 — unknown 18:50–18:55 (marginal, 0.08 h) 71.2° 13:20 11.39 75% 92.1°
2047-01-07 Mon 1 — unknown — 71.1° 13:15 11.37 83% 101.3°
2047-01-08 Tue 1 — unknown — 71.1° 13:10 11.36 90% 110.5°
2047-01-09 Wed 1 — unknown — 71.1° 13:10 11.34 95% 119.3°
2047-01-10 Thu 1 — unknown — 71.1° 13:05 11.33 98% 127.5°
2047-01-11 Fri 1 — unknown — 71.2° 13:00 11.31 100% 134.2°
2047-01-12 Sat 0 — unknown — 71.1° 12:55 11.29 99% 138.4°
2047-01-13 Sun 0 — unknown — 71.1° 12:50 11.27 96% 139.0°
2047-01-14 Mon 0 — unknown — 71.1° 12:50 11.25 90% 135.9°
2047-01-15 Tue 0 — unknown — 71.2° 12:45 11.23 82% 129.5°
2047-01-16 Wed 0 — unknown — 71.2° 12:40 11.21 72% 121.0°
2047-01-17 Thu 0 — unknown — 71.1° 12:35 11.18 61% 111.3°
2047-01-18 Fri 0 — unknown — 71.1° 12:35 11.16 50% 101.0°
2047-01-19 Sat 0 — unknown — 71.1° 12:30 11.13 39% 90.4°
2047-01-20 Sun 0 — unknown — 71.2° 12:25 11.11 28% 79.8°
2047-01-21 Mon 0 — unknown — 71.1° 12:20 11.08 19% 69.6°
2047-01-22 Tue 0 — unknown — 71.1° 12:15 11.06 11% 60.1°
2047-01-23 Wed 0 — unknown — 71.1° 12:15 11.03 5% 51.8°
2047-01-24 Thu 0 — unknown — 71.1° 12:10 11.0 1% 45.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2046-12-26&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.