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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: 09-08 (100), 09-09 (100), 09-10 (100), 09-11 (100), 09-12 (100) — by astronomy; check the weather when the night is within four days.
2026-08-28astronomy score per night — click a bar for that night2026-09-26
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-08-28 Fri 38 88 33 01:20–05:05 (marginal, 3.75 h) 72.5° 06:40 7.39 99% 75.1°
2026-08-29 Sat 28 0 0 — 72.5° 06:35 7.44 97% 62.0°
2026-08-30 Sun 21 100 21 01:30–05:10 (marginal, 3.67 h) 72.5° 06:30 7.5 92% 48.7°
2026-08-31 Mon 16 100 16 01:35–05:10 (marginal, 3.58 h) 72.5° 06:30 7.56 85% 35.2°
2026-09-01 Tue 19 85 16 01:15–04:00 (marginal, 2.75 h) 72.5° 06:25 7.61 76% 21.5°
2026-09-02 Wed 28 1 0 — 72.5° 06:20 7.67 66% 7.7°
2026-09-03 Thu 41 87 36 00:45–05:15 (marginal, 4.5 h) 72.5° 06:15 7.72 55% 6.5°
2026-09-04 Fri 56 100 56 01:30–05:15 (good, 3.75 h) 72.5° 06:10 7.78 43% 20.6°
2026-09-05 Sat 75 100 75 01:15–05:15 (good, 4.0 h) 72.5° 06:10 7.83 32% 34.8°
2026-09-06 Sun 90 100 90 01:00–05:20 (good, 4.33 h) 72.5° 06:05 7.89 22% 49.1°
2026-09-07 Mon 96 100 96 00:55–05:20 (good, 4.42 h) 72.5° 06:00 7.94 13% 63.4°
2026-09-08 Tue 100 100 100 00:50–05:20 (good, 4.5 h) 72.5° 05:55 8.0 6% 77.7°
2026-09-09 Wed 100 80 80 00:50–05:00 (good, 4.17 h) 72.5° 05:50 8.05 2% 91.8°
2026-09-10 Thu 100 100 100 00:45–05:25 (good, 4.67 h) 72.5° 05:50 8.11 0% 105.8°
2026-09-11 Fri 100 100 100 00:40–05:25 (good, 4.75 h) 72.5° 05:45 8.16 1% 119.5°
2026-09-12 Sat 100 0 0 — 72.5° 05:40 8.21 4% 132.8°
2026-09-13 Sun 100 91 91 00:55–05:30 (good, 4.58 h) 72.5° 05:35 8.27 9% 145.8°
2026-09-14 Mon 100 37 37 00:35–02:00 (good, 1.42 h) 72.5° 05:35 8.32 15% 158.5°
2026-09-15 Tue 100 85 85 01:35–05:30 (good, 3.92 h) 72.5° 05:30 8.37 23% 170.8°
2026-09-16 Wed 100 99 99 00:20–05:30 (good, 5.17 h) 72.5° 05:25 8.42 32% 176.8°
2026-09-17 Thu 100 100 100 00:15–05:30 (good, 5.25 h) 72.5° 05:20 8.48 41% 165.0°
2026-09-18 Fri 100 91 91 00:15–05:35 (good, 5.33 h) 72.5° 05:15 8.53 51% 153.1°
2026-09-19 Sat 100 76 76 00:10–02:00 (good, 1.83 h) 72.5° 05:15 8.58 60% 141.3°
2026-09-20 Sun 100 99 99 00:10–05:35 (good, 5.42 h) 72.5° 05:10 8.63 69% 129.4°
2026-09-21 Mon 100 0 0 — 72.5° 05:05 8.68 78% 117.3°
2026-09-22 Tue 100 42 42 04:00–05:40 (good, 1.67 h) 72.5° 05:00 8.73 85% 105.1°
2026-09-23 Wed 100 96 96 01:05–05:40 (good, 4.58 h) 72.5° 04:55 8.78 92% 92.5°
2026-09-24 Thu 100 71 71 02:05–04:00 (good, 1.92 h) 72.5° 04:55 8.84 96% 79.6°
2026-09-25 Fri 61 0 0 — 72.5° 04:50 8.89 99% 66.5°
2026-09-26 Sat 41 0 0 — 72.5° 04:45 8.94 100% 53.0°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-08-28&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.