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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: 06-24 (100), 06-25 (100), 06-26 (100), 06-27 (100), 06-28 (100) — by astronomy; check the weather when the night is within four days.
2031-06-24astronomy score per night — click a bar for that night2031-07-23
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2031-06-24 Tue 100 — unknown 23:15–03:40 (good, 4.42 h) 71.1° 03:10 4.43 21% 139.3°
2031-06-25 Wed 100 — unknown 23:15–03:40 (good, 4.42 h) 71.1° 03:05 4.44 30% 133.6°
2031-06-26 Thu 100 — unknown 23:15–03:40 (good, 4.42 h) 71.1° 03:05 4.45 39% 126.1°
2031-06-27 Fri 100 — unknown 23:15–03:40 (good, 4.42 h) 71.1° 03:00 4.46 49% 117.2°
2031-06-28 Sat 100 — unknown 23:15–03:40 (good, 4.42 h) 71.1° 02:55 4.48 60% 107.4°
2031-06-29 Sun 100 — unknown 23:10–03:40 (good, 4.5 h) 71.1° 02:50 4.5 70% 96.8°
2031-06-30 Mon 100 — unknown 23:10–03:45 (good, 4.58 h) 71.1° 02:50 4.51 80% 85.8°
2031-07-01 Tue 100 — unknown 23:10–03:45 (good, 4.58 h) 71.1° 02:45 4.53 88% 74.4°
2031-07-02 Wed 64 — unknown 00:25–03:45 (good, 3.33 h) 71.1° 02:40 4.56 95% 63.2°
2031-07-03 Thu 47 — unknown 03:30–03:45 (good, 0.25 h) 71.1° 02:35 4.58 99% 52.7°
2031-07-04 Fri 36 — unknown 23:10–03:45 (marginal, 4.58 h) 71.1° 02:30 4.6 100% 43.9°
2031-07-05 Sat 32 — unknown 23:10–03:45 (marginal, 4.58 h) 71.1° 02:30 4.63 98% 38.4°
2031-07-06 Sun 38 — unknown 23:10–03:50 (marginal, 4.67 h) 71.1° 02:25 4.66 93% 37.6°
2031-07-07 Mon 50 — unknown 23:10–00:20 (good, 1.17 h) 71.1° 02:20 4.69 86% 41.6°
2031-07-08 Tue 88 — unknown 23:05–02:45 (good, 3.67 h) 71.1° 02:15 4.72 77% 48.9°
2031-07-09 Wed 96 — unknown 23:05–03:50 (good, 4.75 h) 71.1° 02:10 4.76 66% 57.9°
2031-07-10 Thu 100 — unknown 23:05–03:55 (good, 4.83 h) 71.1° 02:10 4.79 56% 67.7°
2031-07-11 Fri 100 — unknown 23:05–03:55 (good, 4.83 h) 71.1° 02:05 4.83 45% 77.8°
2031-07-12 Sat 100 — unknown 23:05–03:55 (good, 4.83 h) 71.1° 02:00 4.87 36% 87.8°
2031-07-13 Sun 100 — unknown 23:00–03:55 (good, 4.92 h) 71.1° 01:55 4.91 26% 97.6°
2031-07-14 Mon 100 — unknown 23:00–04:00 (good, 5.0 h) 71.1° 01:55 4.95 18% 107.1°
2031-07-15 Tue 100 — unknown 23:00–04:00 (good, 5.0 h) 71.1° 01:50 4.99 12% 116.2°
2031-07-16 Wed 100 — unknown 23:00–04:00 (good, 5.0 h) 71.1° 01:45 5.03 6% 124.7°
2031-07-17 Thu 100 — unknown 23:00–04:00 (good, 5.0 h) 71.1° 01:40 5.08 2% 132.1°
2031-07-18 Fri 100 — unknown 22:55–04:05 (good, 5.17 h) 71.1° 01:35 5.12 0% 138.1°
2031-07-19 Sat 100 — unknown 22:55–04:05 (good, 5.17 h) 71.1° 01:35 5.17 0% 141.8°
2031-07-20 Sun 100 — unknown 22:55–04:05 (good, 5.17 h) 71.1° 01:30 5.21 2% 142.6°
2031-07-21 Mon 100 — unknown 22:50–04:10 (good, 5.33 h) 71.1° 01:25 5.26 5% 140.2°
2031-07-22 Tue 100 — unknown 22:50–04:10 (good, 5.33 h) 71.1° 01:20 5.31 10% 135.0°
2031-07-23 Wed 100 — unknown 22:50–04:10 (good, 5.33 h) 71.1° 01:15 5.36 17% 127.9°

Download: CSV · JSON

💡 API 
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-06-24&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.