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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: 05-27 (13), 05-26 (12), 05-25 (11), 05-23 (10), 05-24 (10) — by astronomy; check the weather when the night is within four days.
2039-04-28astronomy score per night — click a bar for that night2039-05-27
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2039-04-28 Thu 1 — unknown — 89.5° 11:35 6.55 25% 73.2°
2039-04-29 Fri 1 — unknown — 89.6° 11:35 6.49 34% 82.6°
2039-04-30 Sat 1 — unknown — 89.8° 11:30 6.43 43% 92.3°
2039-05-01 Sun 1 — unknown — 89.8° 11:25 6.37 53% 102.2°
2039-05-02 Mon 1 — unknown — 89.6° 11:20 6.31 64% 112.1°
2039-05-03 Tue 1 — unknown — 89.5° 11:20 6.26 74% 121.8°
2039-05-04 Wed 1 — unknown — 89.7° 11:15 6.2 83% 130.8°
2039-05-05 Thu 1 — unknown — 89.8° 11:10 6.14 91% 138.1°
2039-05-06 Fri 1 — unknown — 89.7° 11:05 6.08 96% 142.1°
2039-05-07 Sat 2 — unknown — 89.6° 11:00 6.03 100% 141.5°
2039-05-08 Sun 2 — unknown — 89.6° 11:00 5.97 100% 136.2°
2039-05-09 Mon 2 — unknown — 89.7° 10:55 5.91 97% 127.6°
2039-05-10 Tue 2 — unknown — 89.8° 10:50 5.86 91% 117.2°
2039-05-11 Wed 2 — unknown 04:10–04:15 (marginal, 0.08 h) 89.7° 10:45 5.8 83% 106.1°
2039-05-12 Thu 2 — unknown 04:05–04:10 (marginal, 0.08 h) 89.5° 10:40 5.75 74% 94.8°
2039-05-13 Fri 3 — unknown 04:00–04:10 (marginal, 0.17 h) 89.6° 10:40 5.69 63% 83.8°
2039-05-14 Sat 3 — unknown 03:55–04:10 (marginal, 0.25 h) 89.8° 10:35 5.64 52% 73.2°
2039-05-15 Sun 3 — unknown 03:55–04:05 (marginal, 0.17 h) 89.8° 10:30 5.59 42% 63.3°
2039-05-16 Mon 4 — unknown 03:50–04:05 (marginal, 0.25 h) 89.7° 10:25 5.53 32% 54.3°
2039-05-17 Tue 6 — unknown 03:45–04:05 (marginal, 0.33 h) 89.5° 10:25 5.48 23% 46.7°
2039-05-18 Wed 7 — unknown 04:15–04:50 (marginal, 0.58 h) 89.7° 10:20 5.43 15% 41.0°
2039-05-19 Thu 6 — unknown 04:10–04:45 (marginal, 0.58 h) 89.8° 10:15 5.38 9% 37.9°
2039-05-20 Fri 7 — unknown 04:05–04:45 (marginal, 0.67 h) 89.7° 10:10 5.33 4% 38.0°
2039-05-21 Sat 8 — unknown 04:05–04:45 (marginal, 0.67 h) 89.6° 10:05 5.28 1% 41.1°
2039-05-22 Sun 9 — unknown 04:00–04:45 (marginal, 0.75 h) 89.6° 10:05 5.23 0% 46.6°
2039-05-23 Mon 10 — unknown 03:20–04:45 (marginal, 1.42 h) 89.7° 10:00 5.18 1% 53.8°
2039-05-24 Tue 10 — unknown 03:50–03:55 (good, 0.08 h) 89.8° 09:55 5.13 3% 62.0°
2039-05-25 Wed 11 — unknown 03:45–03:55 (good, 0.17 h) 89.7° 09:50 5.09 7% 70.8°
2039-05-26 Thu 12 — unknown 03:45–03:50 (good, 0.08 h) 89.5° 09:45 5.04 13% 80.1°
2039-05-27 Fri 13 — unknown 03:40–03:50 (good, 0.17 h) 89.6° 09:45 5.0 20% 89.7°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-28&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.