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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: 12-25 (19), 12-26 (18), 12-27 (17), 12-28 (15), 12-29 (13) — by astronomy; check the weather when the night is within four days.
2035-12-25astronomy score per night — click a bar for that night2036-01-23
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2035-12-25 Tue 19 — unknown 18:40–19:15 (good, 0.58 h) 71.1° 14:10 11.5 12% 75.7°
2035-12-26 Wed 18 — unknown 18:40–19:10 (good, 0.5 h) 71.1° 14:05 11.5 7% 66.8°
2035-12-27 Thu 17 — unknown 18:40–19:05 (good, 0.42 h) 71.1° 14:00 11.49 3% 58.6°
2035-12-28 Fri 15 — unknown 18:40–19:00 (good, 0.33 h) 71.1° 13:55 11.49 0% 51.3°
2035-12-29 Sat 13 — unknown 18:40–19:00 (good, 0.33 h) 71.1° 13:50 11.48 0% 45.5°
2035-12-30 Sun 11 — unknown 18:40–18:55 (good, 0.25 h) 71.1° 13:50 11.47 2% 41.7°
2035-12-31 Mon 9 — unknown 18:45–18:50 (good, 0.08 h) 71.1° 13:45 11.46 5% 40.4°
2036-01-01 Tue 7 — unknown 18:10–19:15 (marginal, 1.08 h) 71.1° 13:40 11.45 10% 42.0°
2036-01-02 Wed 6 — unknown 18:45–19:10 (marginal, 0.42 h) 71.1° 13:35 11.44 16% 46.1°
2036-01-03 Thu 5 — unknown 18:45–19:05 (marginal, 0.33 h) 71.1° 13:35 11.43 23% 52.2°
2036-01-04 Fri 3 — unknown 18:45–19:00 (marginal, 0.25 h) 71.1° 13:30 11.42 32% 59.9°
2036-01-05 Sat 3 — unknown 18:45–19:00 (marginal, 0.25 h) 71.1° 13:25 11.41 42% 68.5°
2036-01-06 Sun 2 — unknown 18:45–18:55 (marginal, 0.17 h) 71.1° 13:20 11.39 52% 78.0°
2036-01-07 Mon 1 — unknown — 71.1° 13:15 11.38 62% 88.0°
2036-01-08 Tue 1 — unknown — 71.1° 13:15 11.36 73% 98.4°
2036-01-09 Wed 1 — unknown — 71.1° 13:10 11.35 82% 108.9°
2036-01-10 Thu 1 — unknown — 71.1° 13:05 11.33 90% 119.2°
2036-01-11 Fri 1 — unknown — 71.1° 13:00 11.31 96% 128.5°
2036-01-12 Sat 0 — unknown — 71.1° 12:55 11.29 100% 135.7°
2036-01-13 Sun 0 — unknown — 71.1° 12:55 11.28 100% 139.4°
2036-01-14 Mon 0 — unknown — 71.1° 12:50 11.26 97% 138.5°
2036-01-15 Tue 0 — unknown — 71.1° 12:45 11.23 91% 133.4°
2036-01-16 Wed 0 — unknown — 71.1° 12:40 11.21 83% 125.6°
2036-01-17 Thu 0 — unknown — 71.1° 12:40 11.19 74% 116.4°
2036-01-18 Fri 0 — unknown — 71.1° 12:35 11.17 64% 106.7°
2036-01-19 Sat 0 — unknown — 71.1° 12:30 11.14 54% 96.8°
2036-01-20 Sun 0 — unknown — 71.1° 12:25 11.12 43% 87.1°
2036-01-21 Mon 0 — unknown — 71.1° 12:20 11.09 34% 77.7°
2036-01-22 Tue 0 — unknown — 71.1° 12:20 11.07 25% 68.8°
2036-01-23 Wed 0 — unknown — 71.1° 12:15 11.04 17% 60.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-12-25&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.