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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.

2027-05-01astronomy score per night — click a bar for that night2027-05-30
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2027-05-01 Sat 0 — unknown — 79.1° 12:20 6.38 22% 49.6°
2027-05-02 Sun 0 — unknown — 79.1° 12:15 6.32 14% 37.8°
2027-05-03 Mon 0 — unknown — 79.1° 12:10 6.26 8% 26.4°
2027-05-04 Tue 0 — unknown — 79.1° 12:10 6.2 3% 17.0°
2027-05-05 Wed 0 — unknown — 79.1° 12:00 6.15 0% 15.2°
2027-05-06 Thu 0 — unknown — 79.1° 12:00 6.09 0% 23.6°
2027-05-07 Fri 0 — unknown — 79.1° 11:55 6.03 3% 35.7°
2027-05-08 Sat 0 — unknown — 79.1° 11:50 5.98 8% 49.1°
2027-05-09 Sun 0 — unknown — 79.1° 11:45 5.92 16% 62.9°
2027-05-10 Mon 0 — unknown — 79.1° 11:40 5.86 25% 76.8°
2027-05-11 Tue 0 — unknown — 79.1° 11:35 5.81 36% 90.7°
2027-05-12 Wed 0 — unknown — 79.1° 11:35 5.75 47% 104.4°
2027-05-13 Thu 0 — unknown — 79.1° 11:30 5.7 58% 117.9°
2027-05-14 Fri 0 — unknown — 79.1° 11:25 5.64 69% 131.1°
2027-05-15 Sat 0 — unknown — 79.1° 11:20 5.59 79% 143.7°
2027-05-16 Sun 0 — unknown — 79.1° 11:15 5.54 87% 155.4°
2027-05-17 Mon 0 — unknown — 79.1° 11:15 5.48 93% 164.0°
2027-05-18 Tue 0 — unknown — 79.1° 11:10 5.43 97% 164.3°
2027-05-19 Wed 0 — unknown — 79.1° 11:05 5.38 100% 156.3°
2027-05-20 Thu 0 — unknown — 79.1° 11:00 5.33 100% 145.6°
2027-05-21 Fri 0 — unknown — 79.1° 11:00 5.28 98% 134.2°
2027-05-22 Sat 0 — unknown — 79.1° 10:55 5.23 94% 122.7°
2027-05-23 Sun 0 — unknown — 79.1° 10:50 5.19 89% 111.1°
2027-05-24 Mon 0 — unknown — 79.1° 10:45 5.14 82% 99.6°
2027-05-25 Tue 0 — unknown — 79.1° 10:40 5.09 74% 88.1°
2027-05-26 Wed 0 — unknown — 79.1° 10:40 5.05 66% 76.6°
2027-05-27 Thu 0 — unknown — 79.1° 10:35 5.0 56% 65.1°
2027-05-28 Fri 0 — unknown — 79.1° 10:30 4.96 47% 53.6°
2027-05-29 Sat 0 — unknown — 79.1° 10:25 4.92 37% 42.0°
2027-05-30 Sun 0 — unknown — 79.1° 10:20 4.88 27% 30.5°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-05-01&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.