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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 Andromeda Galaxy: 05-30 (12), 05-29 (11), 05-28 (10), 05-27 (8), 05-21 (7) — by astronomy; check the weather when the night is within four days.
2027-05-01astronomy score per night — click a bar for that night2027-05-30
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2027-05-01 Sat 1 — unknown — 89.7° 11:25 6.38 22% 50.2°
2027-05-02 Sun 1 — unknown — 89.6° 11:20 6.32 14% 40.8°
2027-05-03 Mon 1 — unknown — 89.5° 11:15 6.26 8% 33.1°
2027-05-04 Tue 1 — unknown — 89.6° 11:15 6.2 3% 28.9°
2027-05-05 Wed 1 — unknown — 89.7° 11:10 6.15 0% 30.0°
2027-05-06 Thu 2 — unknown 05:00–05:05 (marginal, 0.08 h) 89.7° 11:05 6.09 0% 36.4°
2027-05-07 Fri 2 — unknown 05:00–05:05 (marginal, 0.08 h) 89.6° 11:00 6.03 3% 46.1°
2027-05-08 Sat 2 — unknown 04:55–05:00 (marginal, 0.08 h) 89.5° 11:00 5.98 8% 57.5°
2027-05-09 Sun 2 — unknown 04:50–05:00 (marginal, 0.17 h) 89.6° 10:55 5.92 16% 69.7°
2027-05-10 Mon 2 — unknown 04:45–05:00 (marginal, 0.25 h) 89.7° 10:50 5.86 25% 82.3°
2027-05-11 Tue 3 — unknown 04:40–04:55 (marginal, 0.25 h) 89.7° 10:45 5.81 36% 94.9°
2027-05-12 Wed 3 — unknown 04:40–04:55 (marginal, 0.25 h) 89.5° 10:40 5.75 47% 107.2°
2027-05-13 Thu 4 — unknown 04:35–04:55 (marginal, 0.33 h) 89.5° 10:40 5.7 58% 119.2°
2027-05-14 Fri 5 — unknown 04:30–04:55 (marginal, 0.42 h) 89.7° 10:35 5.64 69% 130.4°
2027-05-15 Sat 4 — unknown 04:25–04:50 (marginal, 0.42 h) 89.7° 10:30 5.59 79% 140.3°
2027-05-16 Sun 5 — unknown 04:25–04:50 (marginal, 0.42 h) 89.6° 10:25 5.54 87% 147.9°
2027-05-17 Mon 5 — unknown 04:20–04:50 (marginal, 0.5 h) 89.5° 10:20 5.48 93% 151.4°
2027-05-18 Tue 6 — unknown 03:40–04:05 (marginal, 0.42 h) 89.6° 10:20 5.43 97% 149.6°
2027-05-19 Wed 5 — unknown 04:20–04:45 (marginal, 0.42 h) 89.7° 10:15 5.38 100% 143.5°
2027-05-20 Thu 6 — unknown 03:35–04:00 (marginal, 0.42 h) 89.7° 10:10 5.33 100% 135.0°
2027-05-21 Fri 7 — unknown 03:30–04:00 (marginal, 0.5 h) 89.6° 10:05 5.28 98% 125.4°
2027-05-22 Sat 7 — unknown 03:25–03:55 (marginal, 0.5 h) 89.5° 10:05 5.23 94% 115.2°
2027-05-23 Sun 7 — unknown 03:20–03:55 (marginal, 0.58 h) 89.6° 10:00 5.19 89% 104.9°
2027-05-24 Mon 7 — unknown 03:20–03:55 (marginal, 0.58 h) 89.7° 09:55 5.14 82% 94.4°
2027-05-25 Tue 7 — unknown 03:15–03:55 (marginal, 0.67 h) 89.7° 09:50 5.09 74% 84.0°
2027-05-26 Wed 7 — unknown 03:10–03:50 (marginal, 0.67 h) 89.6° 09:45 5.05 66% 73.7°
2027-05-27 Thu 8 — unknown 03:05–03:50 (marginal, 0.75 h) 89.5° 09:45 5.0 56% 63.4°
2027-05-28 Fri 10 — unknown 03:00–03:50 (marginal, 0.83 h) 89.7° 09:40 4.96 47% 53.4°
2027-05-29 Sat 11 — unknown 03:00–04:40 (marginal, 1.67 h) 89.7° 09:35 4.92 37% 44.0°
2027-05-30 Sun 12 — unknown 03:40–03:45 (good, 0.08 h) 89.7° 09:30 4.88 27% 35.6°

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.