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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: 04-22 (66), 04-23 (66), 04-21 (65), 04-19 (63), 04-20 (63) — by astronomy; check the weather when the night is within four days.
2026-03-25astronomy score per night — click a bar for that night2026-04-23
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-03-25 Wed 41 72 30 03:10–04:00 (good, 0.83 h) 71.1° 08:10 8.46 52% 125.0°
2026-03-26 Thu 41 0 0 — 71.1° 08:05 8.41 63% 131.2°
2026-03-27 Fri 42 7 3 02:55–03:00 (marginal, 0.08 h) 71.1° 08:00 8.35 73% 134.7°
2026-03-28 Sat 40 0 0 — 71.1° 08:55 8.3 82% 135.2°
2026-03-29 Sun 37 0 0 — 71.1° 08:50 8.25 90% 132.5°
2026-03-30 Mon 37 0 0 — 71.1° 08:50 8.19 95% 127.3°
2026-03-31 Tue 37 0 0 — 71.1° 08:45 8.14 99% 120.5°
2026-04-01 Wed 35 0 0 — 71.1° 08:40 8.08 100% 112.6°
2026-04-02 Thu 32 0 0 — 71.1° 08:35 8.03 99% 104.2°
2026-04-03 Fri 29 0 0 — 71.1° 08:35 7.97 96% 95.5°
2026-04-04 Sat 28 11 3 — 71.1° 08:30 7.92 92% 86.9°
2026-04-05 Sun 27 91 25 04:45–05:20 (good, 0.58 h) 71.1° 08:25 7.86 86% 78.4°
2026-04-06 Mon 27 88 24 04:00–05:00 (good, 1.0 h) 71.1° 08:20 7.8 79% 70.3°
2026-04-07 Tue 29 73 21 05:00–05:20 (good, 0.33 h) 71.1° 08:15 7.75 71% 62.7°
2026-04-08 Wed 30 1 0 — 71.1° 08:15 7.69 62% 55.9°
2026-04-09 Thu 35 5 2 02:50–03:00 (marginal, 0.17 h) 71.1° 08:10 7.64 53% 50.2°
2026-04-10 Fri 44 0 0 — 71.1° 08:05 7.58 43% 46.3°
2026-04-11 Sat 49 2 1 — 71.1° 08:00 7.52 33% 44.6°
2026-04-12 Sun 54 0 0 — 71.1° 07:55 7.47 24% 45.6°
2026-04-13 Mon 56 0 0 — 71.1° 07:55 7.41 16% 49.5°
2026-04-14 Tue 58 14 8 02:50–03:00 (good, 0.17 h) 71.1° 07:50 7.35 9% 55.7°
2026-04-15 Wed 59 0 0 — 71.1° 07:45 7.29 3% 63.9°
2026-04-16 Thu 59 34 20 04:00–05:35 (marginal, 1.58 h) 71.1° 07:40 7.24 0% 73.3°
2026-04-17 Fri 61 96 58 02:40–05:00 (good, 2.33 h) 71.1° 07:40 7.18 0% 83.6°
2026-04-18 Sat 62 96 60 02:40–04:55 (good, 2.25 h) 71.1° 07:35 7.12 3% 94.2°
2026-04-19 Sun 63 89 56 02:30–04:55 (good, 2.42 h) 71.1° 07:30 7.06 9% 104.6°
2026-04-20 Mon 63 92 58 02:25–04:50 (good, 2.42 h) 71.1° 07:25 7.0 16% 114.5°
2026-04-21 Tue 65 0 0 — 71.1° 07:20 6.95 26% 123.2°
2026-04-22 Wed 66 0 0 — 71.1° 07:20 6.89 37% 130.0°
2026-04-23 Thu 66 57 38 02:20–04:00 (good, 1.67 h) 71.1° 07:15 6.83 48% 134.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-03-25&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.