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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: 05-17 (93), 05-16 (92), 05-18 (92), 05-14 (91), 05-15 (91) — by astronomy; check the weather when the night is within four days.
2040-04-19astronomy score per night — click a bar for that night2040-05-18
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2040-04-19 Thu 62 — unknown 02:30–04:55 (good, 2.42 h) 71.1° 07:30 7.03 54% 133.2°
2040-04-20 Fri 62 — unknown 02:30–04:50 (good, 2.33 h) 71.1° 07:25 6.97 63% 132.4°
2040-04-21 Sat 62 — unknown 02:25–04:50 (good, 2.42 h) 71.1° 07:20 6.91 72% 129.3°
2040-04-22 Sun 56 — unknown 02:25–04:45 (good, 2.33 h) 71.1° 07:15 6.85 81% 124.2°
2040-04-23 Mon 55 — unknown 02:20–04:45 (good, 2.42 h) 71.1° 07:10 6.79 88% 117.5°
2040-04-24 Tue 50 — unknown 02:25–04:45 (good, 2.33 h) 71.1° 07:10 6.74 94% 109.5°
2040-04-25 Wed 44 — unknown 02:25–04:40 (good, 2.25 h) 71.1° 07:05 6.68 98% 100.6°
2040-04-26 Thu 39 — unknown 02:50–04:40 (good, 1.83 h) 71.1° 07:00 6.62 100% 91.1°
2040-04-27 Fri 35 — unknown 03:25–04:40 (good, 1.25 h) 71.1° 06:55 6.56 99% 81.4°
2040-04-28 Sat 31 — unknown 03:50–04:35 (good, 0.75 h) 71.1° 06:55 6.5 96% 71.9°
2040-04-29 Sun 31 — unknown 03:55–04:35 (good, 0.67 h) 71.1° 06:50 6.44 90% 63.1°
2040-04-30 Mon 33 — unknown 03:25–04:30 (good, 1.08 h) 71.1° 06:45 6.39 81% 55.5°
2040-05-01 Tue 39 — unknown 02:05–04:30 (good, 2.42 h) 71.1° 06:40 6.33 71% 49.9°
2040-05-02 Wed 56 — unknown 01:35–04:30 (good, 2.92 h) 71.1° 06:35 6.27 60% 47.1°
2040-05-03 Thu 65 — unknown 01:30–04:25 (good, 2.92 h) 71.1° 06:35 6.21 49% 47.5°
2040-05-04 Fri 73 — unknown 01:30–04:25 (good, 2.92 h) 71.1° 06:30 6.16 38% 51.0°
2040-05-05 Sat 79 — unknown 01:25–04:25 (good, 3.0 h) 71.1° 06:25 6.1 27% 56.7°
2040-05-06 Sun 80 — unknown 01:20–04:20 (good, 3.0 h) 71.1° 06:20 6.04 18% 63.9°
2040-05-07 Mon 82 — unknown 01:15–04:20 (good, 3.08 h) 71.1° 06:15 5.98 11% 72.1°
2040-05-08 Tue 84 — unknown 01:10–04:20 (good, 3.17 h) 71.1° 06:15 5.93 5% 80.7°
2040-05-09 Wed 85 — unknown 01:10–04:15 (good, 3.08 h) 71.1° 06:10 5.87 2% 89.5°
2040-05-10 Thu 86 — unknown 01:05–04:15 (good, 3.17 h) 71.1° 06:05 5.82 0% 98.1°
2040-05-11 Fri 87 — unknown 01:00–04:15 (good, 3.25 h) 71.1° 06:00 5.76 1% 106.3°
2040-05-12 Sat 88 — unknown 00:55–04:10 (good, 3.25 h) 71.1° 06:00 5.71 3% 114.0°
2040-05-13 Sun 90 — unknown 00:50–04:10 (good, 3.33 h) 71.1° 05:55 5.65 7% 120.8°
2040-05-14 Mon 91 — unknown 00:50–04:10 (good, 3.33 h) 71.1° 05:50 5.6 13% 126.5°
2040-05-15 Tue 91 — unknown 00:45–04:05 (good, 3.33 h) 71.1° 05:45 5.55 20% 130.6°
2040-05-16 Wed 92 — unknown 00:45–04:05 (good, 3.33 h) 71.1° 05:40 5.49 28% 132.8°
2040-05-17 Thu 93 — unknown 00:40–04:05 (good, 3.42 h) 71.1° 05:40 5.44 37% 132.8°
2040-05-18 Fri 92 — unknown 00:35–04:00 (good, 3.42 h) 71.1° 05:35 5.39 46% 130.5°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-04-19&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.