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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: 08-21 (77), 08-20 (74), 08-19 (66), 08-18 (54), 08-17 (44) — by astronomy; check the weather when the night is within four days.
2025-07-23astronomy score per night — click a bar for that night2025-08-21
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2025-07-23 Wed 15 100 15 03:55–04:10 (good, 0.25 h) 72.5° 09:00 5.38 1% 50.2°
2025-07-24 Thu 17 100 17 03:50–04:15 (good, 0.42 h) 72.5° 08:55 5.43 0% 64.1°
2025-07-25 Fri 19 100 19 03:45–04:15 (good, 0.5 h) 72.5° 08:50 5.48 2% 77.7°
2025-07-26 Sat 20 100 20 03:45–04:15 (good, 0.5 h) 72.5° 08:50 5.54 5% 91.0°
2025-07-27 Sun 23 92 21 03:55–04:20 (good, 0.42 h) 72.5° 08:45 5.59 11% 103.9°
2025-07-28 Mon 25 99 25 03:35–04:20 (good, 0.75 h) 72.5° 08:40 5.64 18% 116.5°
2025-07-29 Tue 26 99 26 03:30–04:20 (good, 0.83 h) 72.5° 08:35 5.7 26% 128.8°
2025-07-30 Wed 28 0 0 — 72.5° 08:35 5.75 35% 140.9°
2025-07-31 Thu 30 33 10 04:00–04:25 (marginal, 0.42 h) 72.5° 08:30 5.81 44% 152.8°
2025-08-01 Fri 32 87 28 03:35–04:25 (good, 0.83 h) 72.5° 08:25 5.86 54% 164.6°
2025-08-02 Sat 33 100 33 03:15–04:25 (good, 1.17 h) 72.5° 08:20 5.92 63% 176.4°
2025-08-03 Sun 35 97 34 03:10–04:30 (good, 1.33 h) 72.5° 08:15 5.97 72% 171.5°
2025-08-04 Mon 38 52 20 03:15–04:00 (good, 0.75 h) 72.5° 08:15 6.03 80% 159.4°
2025-08-05 Tue 39 64 25 04:00–04:30 (good, 0.5 h) 72.5° 08:10 6.08 88% 147.1°
2025-08-06 Wed 41 77 32 03:30–04:35 (good, 1.08 h) 72.5° 08:05 6.14 94% 134.4°
2025-08-07 Thu 37 70 26 04:00–04:35 (good, 0.58 h) 72.5° 08:00 6.2 98% 121.5°
2025-08-08 Fri 33 100 33 03:10–04:35 (good, 1.42 h) 72.5° 07:55 6.25 100% 108.2°
2025-08-09 Sat 28 100 28 03:20–04:40 (good, 1.33 h) 72.5° 07:55 6.31 100% 94.7°
2025-08-10 Sun 23 100 23 04:30–04:40 (good, 0.17 h) 72.5° 07:50 6.37 97% 80.9°
2025-08-11 Mon 18 100 18 02:30–04:40 (marginal, 2.17 h) 72.5° 07:45 6.43 92% 66.9°
2025-08-12 Tue 15 100 15 02:30–04:45 (marginal, 2.25 h) 72.5° 07:40 6.48 84% 52.8°
2025-08-13 Wed 14 100 14 02:25–04:45 (marginal, 2.33 h) 72.5° 07:40 6.54 75% 38.6°
2025-08-14 Thu 17 59 10 02:15–04:00 (marginal, 1.75 h) 72.5° 07:35 6.6 65% 24.3°
2025-08-15 Fri 24 100 24 02:00–04:50 (marginal, 2.83 h) 72.5° 07:30 6.66 53% 10.2°
2025-08-16 Sat 34 97 33 03:40–04:50 (good, 1.17 h) 72.5° 07:25 6.71 42% 4.1°
2025-08-17 Sun 44 94 41 02:35–04:50 (good, 2.25 h) 72.5° 07:20 6.77 31% 18.1°
2025-08-18 Mon 54 26 14 01:50–02:00 (marginal, 0.17 h) 72.5° 07:20 6.83 21% 32.1°
2025-08-19 Tue 66 0 0 — 72.5° 07:15 6.89 13% 45.9°
2025-08-20 Wed 74 100 74 02:05–04:55 (good, 2.83 h) 72.5° 07:10 6.94 6% 59.6°
2025-08-21 Thu 77 100 77 02:00–04:55 (good, 2.92 h) 72.5° 07:05 7.0 2% 73.1°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2025-07-23&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.