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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 (17), 12-27 (14), 12-28 (11), 12-29 (8) — by astronomy; check the weather when the night is within four days.
2030-12-25astronomy score per night — click a bar for that night2031-01-23
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2030-12-25 Wed 19 — unknown 18:40–19:15 (good, 0.58 h) 71.1° 14:05 11.5 2% 41.6°
2030-12-26 Thu 17 — unknown 18:40–19:05 (good, 0.42 h) 71.1° 14:05 11.5 7% 37.8°
2030-12-27 Fri 14 — unknown 18:40–19:00 (good, 0.33 h) 71.1° 14:00 11.49 14% 38.7°
2030-12-28 Sat 11 — unknown 18:40–18:50 (good, 0.17 h) 71.1° 13:55 11.48 23% 43.6°
2030-12-29 Sun 8 — unknown 18:10–19:25 (marginal, 1.25 h) 71.1° 13:50 11.48 33% 51.2°
2030-12-30 Mon 7 — unknown 18:40–19:20 (marginal, 0.67 h) 71.1° 13:45 11.47 44% 60.0°
2030-12-31 Tue 5 — unknown 18:45–19:15 (marginal, 0.5 h) 71.1° 13:45 11.46 54% 69.4°
2031-01-01 Wed 4 — unknown 18:45–19:10 (marginal, 0.42 h) 71.1° 13:40 11.45 64% 79.0°
2031-01-02 Thu 4 — unknown 18:45–19:10 (marginal, 0.42 h) 71.1° 13:35 11.44 72% 88.6°
2031-01-03 Fri 3 — unknown 18:45–19:05 (marginal, 0.33 h) 71.1° 13:30 11.43 81% 98.1°
2031-01-04 Sat 3 — unknown 18:45–19:00 (marginal, 0.25 h) 71.1° 13:30 11.42 88% 107.4°
2031-01-05 Sun 3 — unknown 18:45–18:55 (marginal, 0.17 h) 71.1° 13:25 11.4 93% 116.3°
2031-01-06 Mon 2 — unknown 18:50–18:55 (marginal, 0.08 h) 71.1° 13:20 11.39 97% 124.7°
2031-01-07 Tue 1 — unknown — 71.1° 13:15 11.38 99% 132.1°
2031-01-08 Wed 1 — unknown — 71.1° 13:10 11.36 100% 138.0°
2031-01-09 Thu 1 — unknown — 71.1° 13:10 11.34 99% 141.7°
2031-01-10 Fri 1 — unknown — 71.1° 13:05 11.33 96% 142.2°
2031-01-11 Sat 1 — unknown — 71.1° 13:00 11.31 91% 139.6°
2031-01-12 Sun 1 — unknown — 71.1° 12:55 11.29 84% 134.1°
2031-01-13 Mon 0 — unknown — 71.1° 12:50 11.27 76% 126.5°
2031-01-14 Tue 0 — unknown — 71.1° 12:50 11.25 67% 117.6°
2031-01-15 Wed 0 — unknown — 71.1° 12:45 11.23 56% 107.7°
2031-01-16 Thu 0 — unknown — 71.1° 12:40 11.21 46% 97.2°
2031-01-17 Fri 0 — unknown — 71.1° 12:35 11.19 35% 86.2°
2031-01-18 Sat 0 — unknown — 71.1° 12:35 11.16 24% 75.0°
2031-01-19 Sun 0 — unknown — 71.1° 12:30 11.14 15% 63.9°
2031-01-20 Mon 0 — unknown — 71.1° 12:25 11.11 7% 53.5°
2031-01-21 Tue 0 — unknown — 71.1° 12:20 11.09 2% 44.7°
2031-01-22 Wed 0 — unknown — 71.1° 12:15 11.06 0% 39.0°
2031-01-23 Thu 0 — unknown — 71.1° 12:15 11.03 1% 37.7°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-12-25&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.