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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: 07-31 (17), 07-30 (13), 07-23 (12), 07-24 (12), 07-21 (11) — by astronomy; check the weather when the night is within four days.
2040-07-02astronomy score per night — click a bar for that night2040-07-31
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2040-07-02 Mon 0 — unknown — 72.5° 10:20 4.57 34% 30.8°
2040-07-03 Tue 0 — unknown — 72.5° 10:20 4.6 25% 18.4°
2040-07-04 Wed 0 — unknown — 72.5° 10:15 4.63 17% 7.1°
2040-07-05 Thu 0 — unknown — 72.5° 10:10 4.66 10% 8.0°
2040-07-06 Fri 0 — unknown — 72.5° 10:05 4.69 5% 19.2°
2040-07-07 Sat 1 — unknown — 72.5° 10:00 4.72 2% 30.9°
2040-07-08 Sun 1 — unknown — 72.5° 10:00 4.75 0% 42.6°
2040-07-09 Mon 1 — unknown — 72.5° 09:55 4.79 0% 54.4°
2040-07-10 Tue 1 — unknown — 72.5° 09:50 4.82 2% 66.1°
2040-07-11 Wed 2 — unknown 04:40–04:45 (marginal, 0.08 h) 72.5° 09:45 4.86 6% 78.0°
2040-07-12 Thu 2 — unknown 04:35–04:45 (marginal, 0.17 h) 72.5° 09:45 4.9 11% 89.9°
2040-07-13 Fri 2 — unknown 04:35–04:45 (marginal, 0.17 h) 72.5° 09:40 4.94 18% 101.9°
2040-07-14 Sat 3 — unknown 04:30–04:50 (marginal, 0.33 h) 72.5° 09:35 4.98 26% 114.1°
2040-07-15 Sun 3 — unknown 04:25–04:50 (marginal, 0.42 h) 72.5° 09:30 5.02 35% 126.5°
2040-07-16 Mon 4 — unknown 04:20–04:50 (marginal, 0.5 h) 72.5° 09:25 5.07 45% 139.1°
2040-07-17 Tue 6 — unknown 04:15–04:50 (marginal, 0.58 h) 72.5° 09:25 5.11 56% 152.1°
2040-07-18 Wed 7 — unknown 04:15–04:50 (marginal, 0.58 h) 72.5° 09:20 5.16 66% 165.3°
2040-07-19 Thu 8 — unknown 04:10–04:55 (marginal, 0.75 h) 72.5° 09:15 5.21 77% 175.7°
2040-07-20 Fri 10 — unknown 04:05–04:10 (good, 0.08 h) 72.5° 09:10 5.25 86% 165.1°
2040-07-21 Sat 11 — unknown 04:00–04:10 (good, 0.17 h) 72.5° 09:05 5.3 93% 150.6°
2040-07-22 Sun 11 — unknown 04:05–04:10 (good, 0.08 h) 72.5° 09:05 5.35 98% 135.6°
2040-07-23 Mon 12 — unknown 04:05–04:10 (good, 0.08 h) 72.5° 09:00 5.4 100% 120.4°
2040-07-24 Tue 12 — unknown 04:10–04:15 (good, 0.08 h) 72.5° 08:55 5.45 99% 105.3°
2040-07-25 Wed 10 — unknown 03:20–04:15 (marginal, 0.92 h) 72.5° 08:50 5.5 95% 90.3°
2040-07-26 Thu 9 — unknown 03:20–04:15 (marginal, 0.92 h) 72.5° 08:50 5.56 88% 75.6°
2040-07-27 Fri 9 — unknown 03:20–04:20 (marginal, 1.0 h) 72.5° 08:45 5.61 80% 61.4°
2040-07-28 Sat 9 — unknown 03:20–04:20 (marginal, 1.0 h) 72.5° 08:40 5.66 70% 47.6°
2040-07-29 Sun 10 — unknown 03:10–04:20 (marginal, 1.17 h) 72.5° 08:35 5.72 60% 34.4°
2040-07-30 Mon 13 — unknown 03:00–04:25 (marginal, 1.42 h) 72.5° 08:30 5.77 49% 21.6°
2040-07-31 Tue 17 — unknown 03:45–04:25 (good, 0.67 h) 72.5° 08:30 5.83 39% 9.6°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-02&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.