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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: 05-24 (100), 05-25 (100), 05-23 (95), 05-22 (87), 05-08 (81) — by astronomy; check the weather when the night is within four days.
2041-04-26astronomy score per night — click a bar for that night2041-05-25
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
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°
2041-05-11 Sat 71 — unknown 01:15–04:15 (good, 3.0 h) 71.1° 06:00 5.77 83% 112.9°
2041-05-12 Sun 64 — unknown 01:15–04:10 (good, 2.92 h) 71.1° 06:00 5.72 90% 105.2°
2041-05-13 Mon 58 — unknown 01:20–04:10 (good, 2.83 h) 71.1° 05:55 5.67 95% 96.9°
2041-05-14 Tue 51 — unknown 01:50–04:10 (good, 2.33 h) 71.1° 05:50 5.61 99% 88.1°
2041-05-15 Wed 44 — unknown 02:20–04:05 (good, 1.75 h) 71.1° 05:45 5.56 100% 79.2°
2041-05-16 Thu 40 — unknown 02:50–04:05 (good, 1.25 h) 71.1° 05:45 5.51 99% 70.5°
2041-05-17 Fri 38 — unknown 03:10–04:05 (good, 0.92 h) 71.1° 05:40 5.45 96% 62.3°
2041-05-18 Sat 38 — unknown 03:00–04:00 (good, 1.0 h) 71.1° 05:35 5.4 90% 55.3°
2041-05-19 Sun 50 — unknown 01:45–04:00 (good, 2.25 h) 71.1° 05:30 5.35 82% 50.1°
2041-05-20 Mon 66 — unknown 00:25–04:00 (good, 3.58 h) 71.1° 05:25 5.3 72% 47.6°
2041-05-21 Tue 77 — unknown 00:20–04:00 (good, 3.67 h) 71.1° 05:25 5.25 62% 48.1°
2041-05-22 Wed 87 — unknown 00:20–03:55 (good, 3.58 h) 71.1° 05:20 5.2 50% 51.8°
2041-05-23 Thu 95 — unknown 00:15–03:55 (good, 3.67 h) 71.1° 05:15 5.16 39% 57.8°
2041-05-24 Fri 100 — unknown 00:10–03:55 (good, 3.75 h) 71.1° 05:10 5.11 28% 65.5°
2041-05-25 Sat 100 — unknown 00:05–03:50 (good, 3.75 h) 71.1° 05:05 5.07 18% 74.1°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-26&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.