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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: 05-08 (81), 05-05 (80), 05-07 (80), 05-09 (80), 05-10 (80) — by astronomy; check the weather when the night is within four days.
2041-04-11astronomy score per night — click a bar for that night2041-05-10
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2041-04-11 Thu 48 — unknown 03:05–05:10 (good, 2.08 h) 71.1° 08:00 7.5 81% 128.6°
2041-04-12 Fri 47 — unknown 03:05–05:05 (good, 2.0 h) 71.1° 07:55 7.44 88% 123.8°
2041-04-13 Sat 46 — unknown 03:05–05:05 (good, 2.0 h) 71.1° 07:55 7.39 94% 117.6°
2041-04-14 Sun 43 — unknown 03:05–05:05 (good, 2.0 h) 71.1° 07:50 7.33 98% 110.4°
2041-04-15 Mon 38 — unknown 03:05–05:00 (good, 1.92 h) 71.1° 07:45 7.27 100% 102.4°
2041-04-16 Tue 35 — unknown 03:20–05:00 (good, 1.67 h) 71.1° 07:40 7.21 100% 94.0°
2041-04-17 Wed 31 — unknown 03:45–04:55 (good, 1.17 h) 71.1° 07:35 7.16 98% 85.2°
2041-04-18 Thu 30 — unknown 04:00–04:55 (good, 0.92 h) 71.1° 07:35 7.1 94% 76.5°
2041-04-19 Fri 29 — unknown 04:00–04:55 (good, 0.92 h) 71.1° 07:30 7.04 88% 68.0°
2041-04-20 Sat 31 — unknown 03:40–04:50 (good, 1.17 h) 71.1° 07:25 6.98 79% 60.3°
2041-04-21 Sun 34 — unknown 02:45–04:50 (good, 2.08 h) 71.1° 07:20 6.92 70% 53.8°
2041-04-22 Mon 47 — unknown 02:15–04:50 (good, 2.58 h) 71.1° 07:15 6.87 59% 49.3°
2041-04-23 Tue 56 — unknown 02:10–04:45 (good, 2.58 h) 71.1° 07:15 6.81 48% 47.4°
2041-04-24 Wed 63 — unknown 02:10–04:45 (good, 2.58 h) 71.1° 07:10 6.75 36% 48.7°
2041-04-25 Thu 68 — unknown 02:05–04:40 (good, 2.58 h) 71.1° 07:05 6.69 26% 53.0°
2041-04-26 Fri 69 — unknown 02:00–04:40 (good, 2.67 h) 71.1° 07:00 6.63 16% 59.6°
2041-04-27 Sat 72 — unknown 01:55–04:40 (good, 2.75 h) 71.1° 07:00 6.57 8% 67.8°
2041-04-28 Sun 72 — unknown 01:50–04:35 (good, 2.75 h) 71.1° 06:55 6.52 3% 76.8°
2041-04-29 Mon 73 — unknown 01:50–04:35 (good, 2.75 h) 71.1° 06:50 6.46 0% 86.3°
2041-04-30 Tue 74 — unknown 01:45–04:30 (good, 2.75 h) 71.1° 06:45 6.4 0% 95.7°
2041-05-01 Wed 75 — unknown 01:40–04:30 (good, 2.83 h) 71.1° 06:40 6.34 2% 104.7°
2041-05-02 Thu 76 — unknown 01:35–04:30 (good, 2.92 h) 71.1° 06:40 6.28 7% 113.0°
2041-05-03 Fri 77 — unknown 01:35–04:25 (good, 2.83 h) 71.1° 06:35 6.23 13% 120.3°
2041-05-04 Sat 78 — unknown 01:30–04:25 (good, 2.92 h) 71.1° 06:30 6.17 21% 126.2°
2041-05-05 Sun 80 — unknown 01:25–04:25 (good, 3.0 h) 71.1° 06:25 6.11 29% 130.3°
2041-05-06 Mon 79 — unknown 01:25–04:20 (good, 2.92 h) 71.1° 06:20 6.05 38% 132.4°
2041-05-07 Tue 80 — unknown 01:20–04:20 (good, 3.0 h) 71.1° 06:20 6.0 48% 132.2°
2041-05-08 Wed 81 — unknown 01:20–04:20 (good, 3.0 h) 71.1° 06:15 5.94 57% 129.8°
2041-05-09 Thu 80 — unknown 01:15–04:15 (good, 3.0 h) 71.1° 06:10 5.89 66% 125.6°
2041-05-10 Fri 80 — unknown 01:15–04:15 (good, 3.0 h) 71.1° 06:05 5.83 75% 119.8°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-11&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.