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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: 05-23 (100), 05-24 (100), 05-25 (100), 05-26 (100), 05-27 (100) — by astronomy; check the weather when the night is within four days.
2025-05-15astronomy score per night — click a bar for that night2025-06-13
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-05-15 Thu 38 0 0 — 71.1° 05:45 5.56 90% 58.3°
2025-05-16 Fri 41 0 0 — 71.1° 05:45 5.51 84% 52.3°
2025-05-17 Sat 58 16 9 00:15–01:00 (marginal, 0.75 h) 71.1° 05:40 5.46 76% 47.9°
2025-05-18 Sun 67 100 67 00:35–04:00 (good, 3.42 h) 71.1° 05:35 5.41 66% 45.9°
2025-05-19 Mon 76 96 73 00:40–04:00 (good, 3.33 h) 71.1° 05:30 5.36 56% 46.6°
2025-05-20 Tue 83 28 24 03:00–04:00 (good, 1.0 h) 71.1° 05:25 5.31 45% 50.1°
2025-05-21 Wed 92 73 68 00:30–02:00 (good, 1.5 h) 71.1° 05:25 5.26 34% 56.2°
2025-05-22 Thu 97 96 93 00:20–03:55 (good, 3.58 h) 71.1° 05:20 5.21 24% 64.1°
2025-05-23 Fri 100 5 5 — 71.1° 05:15 5.16 15% 73.4°
2025-05-24 Sat 100 0 0 — 71.1° 05:10 5.12 7% 83.6°
2025-05-25 Sun 100 0 0 — 71.1° 05:05 5.07 2% 94.1°
2025-05-26 Mon 100 75 75 01:25–03:50 (good, 2.42 h) 71.1° 05:05 5.03 0% 104.5°
2025-05-27 Tue 100 99 99 00:00–03:50 (good, 3.83 h) 71.1° 05:00 4.98 1% 114.2°
2025-05-28 Wed 100 91 91 23:55–03:50 (good, 3.92 h) 71.1° 04:55 4.94 5% 122.7°
2025-05-29 Thu 100 12 12 23:50–01:00 (marginal, 1.17 h) 71.1° 04:50 4.9 11% 129.3°
2025-05-30 Fri 100 22 22 02:00–03:45 (marginal, 1.75 h) 71.1° 04:50 4.86 19% 133.3°
2025-05-31 Sat 100 85 85 00:05–03:45 (good, 3.67 h) 71.1° 04:45 4.82 28% 134.3°
2025-06-01 Sun 100 19 19 23:10–01:00 (marginal, 1.83 h) 71.1° 04:40 4.79 38% 132.4°
2025-06-02 Mon 100 99 99 23:45–03:45 (good, 4.0 h) 71.1° 04:35 4.75 48% 128.2°
2025-06-03 Tue 100 100 100 23:35–03:45 (good, 4.17 h) 71.1° 04:30 4.72 58% 122.4°
2025-06-04 Wed 100 100 100 23:35–03:40 (good, 4.08 h) 71.1° 04:30 4.69 67% 115.5°
2025-06-05 Thu 100 18 18 03:00–03:40 (good, 0.67 h) 71.1° 04:25 4.65 76% 107.9°
2025-06-06 Fri 100 100 100 23:40–03:40 (good, 4.0 h) 71.1° 04:20 4.63 83% 99.9°
2025-06-07 Sat 96 100 96 23:40–03:40 (good, 4.0 h) 71.1° 04:15 4.6 90% 91.6°
2025-06-08 Sun 72 100 72 00:15–03:40 (good, 3.42 h) 71.1° 04:10 4.57 95% 83.3°
2025-06-09 Mon 62 94 58 01:10–03:40 (good, 2.5 h) 71.1° 04:10 4.55 98% 75.1°
2025-06-10 Tue 54 55 30 00:00–03:00 (marginal, 3.0 h) 71.1° 04:05 4.53 100% 67.2°
2025-06-11 Wed 48 94 45 23:10–03:40 (marginal, 4.5 h) 71.1° 04:00 4.51 100% 59.8°
2025-06-12 Thu 44 100 44 23:10–03:40 (marginal, 4.5 h) 71.1° 03:55 4.49 97% 53.4°
2025-06-13 Fri 62 71 44 00:00–03:40 (marginal, 3.67 h) 71.1° 03:55 4.47 93% 48.6°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-05-15&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.