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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 Seven Sisters: 03-16 (40), 03-17 (39), 03-18 (37), 03-15 (36), 03-19 (35) — by astronomy; check the weather when the night is within four days.
2025-03-15astronomy score per night — click a bar for that night2025-04-13
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-03-15 Sat 36 67 24 20:05–20:35 (good, 0.5 h) 72.5° 16:35 8.96 98% 133.9°
2025-03-16 Sun 40 96 38 20:05–21:35 (good, 1.5 h) 72.5° 16:30 8.91 94% 145.8°
2025-03-17 Mon 39 0 0 — 72.5° 16:25 8.86 88% 157.7°
2025-03-18 Tue 37 0 0 — 72.5° 16:25 8.81 82% 169.5°
2025-03-19 Wed 35 100 35 20:10–21:30 (good, 1.33 h) 72.5° 16:20 8.76 74% 178.5°
2025-03-20 Thu 33 100 33 20:10–21:25 (good, 1.25 h) 72.5° 16:15 8.71 65% 166.6°
2025-03-21 Fri 32 100 32 20:10–21:20 (good, 1.17 h) 72.5° 16:10 8.66 55% 154.5°
2025-03-22 Sat 30 0 0 — 72.5° 16:10 8.61 45% 142.1°
2025-03-23 Sun 27 0 0 — 72.5° 16:05 8.55 35% 129.3°
2025-03-24 Mon 26 0 0 — 72.5° 16:00 8.5 26% 116.0°
2025-03-25 Tue 25 0 0 — 72.5° 15:55 8.45 17% 102.4°
2025-03-26 Wed 23 30 7 20:15–21:00 (marginal, 0.75 h) 72.5° 15:50 8.39 9% 88.2°
2025-03-27 Thu 21 0 0 — 72.5° 15:50 8.34 3% 73.6°
2025-03-28 Fri 19 0 0 — 72.5° 15:45 8.29 0% 58.7°
2025-03-29 Sat 18 6 1 — 72.5° 15:40 8.23 0% 43.5°
2025-03-30 Sun 16 0 0 — 72.5° 16:35 8.18 3% 28.4°
2025-03-31 Mon 12 11 1 — 72.5° 16:30 8.12 9% 13.3°
2025-04-01 Tue 9 0 0 — 72.5° 16:30 8.07 17% 1.6°
2025-04-02 Wed 7 0 0 — 72.5° 16:25 8.01 27% 15.9°
2025-04-03 Thu 4 0 0 — 72.5° 16:20 7.96 37% 29.9°
2025-04-04 Fri 3 49 1 — 72.5° 16:15 7.9 48% 43.5°
2025-04-05 Sat 2 91 2 21:30–21:40 (marginal, 0.17 h) 72.5° 16:15 7.85 59% 56.7°
2025-04-06 Sun 2 0 0 — 72.5° 16:10 7.79 69% 69.6°
2025-04-07 Mon 2 100 2 — 72.5° 16:05 7.74 78% 82.2°
2025-04-08 Tue 1 0 0 — 72.5° 16:00 7.68 85% 94.5°
2025-04-09 Wed 1 92 1 — 72.5° 15:55 7.62 92% 106.7°
2025-04-10 Thu 1 0 0 — 72.5° 15:55 7.57 96% 118.8°
2025-04-11 Fri 1 0 0 — 72.5° 15:50 7.51 99% 130.7°
2025-04-12 Sat 1 0 0 — 72.5° 15:45 7.45 100% 142.6°
2025-04-13 Sun 1 100 1 — 72.5° 15:40 7.39 99% 154.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-03-15&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.