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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: 06-01 (97), 05-17 (93), 05-16 (92), 05-18 (92), 05-19 (92) — by astronomy; check the weather when the night is within four days.
2040-05-03astronomy score per night — click a bar for that night2040-06-01
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
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°
2040-05-19 Sat 92 — unknown 00:35–04:00 (good, 3.42 h) 71.1° 05:30 5.34 56% 126.1°
2040-05-20 Sun 92 — unknown 00:30–04:00 (good, 3.5 h) 71.1° 05:25 5.29 66% 120.1°
2040-05-21 Mon 89 — unknown 00:30–03:55 (good, 3.42 h) 71.1° 05:20 5.24 75% 112.7°
2040-05-22 Tue 75 — unknown 00:35–03:55 (good, 3.33 h) 71.1° 05:20 5.19 84% 104.3°
2040-05-23 Wed 66 — unknown 00:40–03:55 (good, 3.25 h) 71.1° 05:15 5.15 91% 95.1°
2040-05-24 Thu 57 — unknown 01:15–03:55 (good, 2.67 h) 71.1° 05:10 5.1 97% 85.5°
2040-05-25 Fri 48 — unknown 02:00–03:50 (good, 1.83 h) 71.1° 05:05 5.05 100% 75.8°
2040-05-26 Sat 42 — unknown 02:40–03:50 (good, 1.17 h) 71.1° 05:05 5.01 100% 66.4°
2040-05-27 Sun 39 — unknown 03:10–03:50 (good, 0.67 h) 71.1° 05:00 4.97 97% 58.0°
2040-05-28 Mon 41 — unknown 03:05–03:15 (good, 0.17 h) 71.1° 04:55 4.93 91% 51.5°
2040-05-29 Tue 64 — unknown 01:10–03:50 (good, 2.67 h) 71.1° 04:50 4.89 84% 47.6°
2040-05-30 Wed 76 — unknown 23:45–03:45 (good, 4.0 h) 71.1° 04:45 4.85 74% 47.1°
2040-05-31 Thu 89 — unknown 23:40–03:45 (good, 4.08 h) 71.1° 04:45 4.81 63% 49.9°
2040-06-01 Fri 97 — unknown 23:40–03:45 (good, 4.08 h) 71.1° 04:40 4.77 52% 55.2°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-05-03&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.