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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: 03-27 (42), 03-25 (41), 03-26 (41), 03-24 (40), 03-28 (40) — by astronomy; check the weather when the night is within four days.
2026-03-01astronomy score per night — click a bar for that night2026-03-30
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-03-01 Sun 18 47 8 04:55–05:00 (good, 0.08 h) 71.1° 09:40 9.65 97% 134.7°
2026-03-02 Mon 18 0 0 — 71.1° 09:40 9.6 100% 131.1°
2026-03-03 Tue 18 99 18 04:45–05:20 (good, 0.58 h) 71.1° 09:35 9.56 100% 125.2°
2026-03-04 Wed 19 0 0 — 71.1° 09:30 9.51 98% 117.9°
2026-03-05 Thu 18 100 18 04:40–05:20 (good, 0.67 h) 71.1° 09:25 9.46 94% 109.7°
2026-03-06 Fri 17 66 11 04:05–05:00 (marginal, 0.92 h) 71.1° 09:25 9.41 88% 101.2°
2026-03-07 Sat 17 82 14 04:40–05:00 (good, 0.33 h) 71.1° 09:20 9.37 81% 92.6°
2026-03-08 Sun 17 32 5 05:00–05:15 (marginal, 0.25 h) 71.1° 09:15 9.32 72% 84.0°
2026-03-09 Mon 17 89 15 04:45–05:00 (good, 0.25 h) 71.1° 09:10 9.27 64% 75.7°
2026-03-10 Tue 19 100 19 04:25–05:10 (good, 0.75 h) 71.1° 09:05 9.22 54% 67.8°
2026-03-11 Wed 21 52 11 04:15–05:00 (marginal, 0.75 h) 71.1° 09:05 9.17 45% 60.4°
2026-03-12 Thu 23 99 23 04:10–05:05 (good, 0.92 h) 71.1° 09:00 9.13 36% 53.9°
2026-03-13 Fri 28 100 28 03:55–05:05 (good, 1.17 h) 71.1° 08:55 9.08 27% 48.7°
2026-03-14 Sat 31 95 30 03:55–05:05 (good, 1.17 h) 71.1° 08:50 9.03 18% 45.4°
2026-03-15 Sun 32 100 32 03:45–05:00 (good, 1.25 h) 71.1° 08:45 8.98 11% 44.7°
2026-03-16 Mon 33 72 24 04:00–05:00 (good, 1.0 h) 71.1° 08:45 8.93 5% 47.0°
2026-03-17 Tue 35 0 0 — 71.1° 08:40 8.88 2% 51.9°
2026-03-18 Wed 35 0 0 — 71.1° 08:35 8.82 0% 59.0°
2026-03-19 Thu 36 0 0 — 71.1° 08:30 8.77 1% 67.7°
2026-03-20 Fri 36 0 0 — 71.1° 08:30 8.72 5% 77.4°
2026-03-21 Sat 37 0 0 — 71.1° 08:25 8.67 11% 87.5°
2026-03-22 Sun 39 0 0 — 71.1° 08:20 8.62 19% 97.8°
2026-03-23 Mon 38 0 0 — 71.1° 08:15 8.57 29% 107.8°
2026-03-24 Tue 40 0 0 — 71.1° 08:10 8.51 40% 117.0°
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°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-03-01&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.