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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: 08-10 (49), 08-09 (44), 08-08 (36), 08-07 (29), 08-06 (22) — by astronomy; check the weather when the night is within four days.
2026-07-12astronomy score per night — click a bar for that night2026-08-10
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-07-12 Sun 2 99 2 04:40–04:45 (marginal, 0.08 h) 72.5° 09:45 4.87 3% 30.0°
2026-07-13 Mon 2 92 2 — 72.5° 09:40 4.91 0% 45.0°
2026-07-14 Tue 2 99 2 04:30–04:45 (marginal, 0.25 h) 72.5° 09:35 4.96 0% 60.0°
2026-07-15 Wed 3 94 3 04:30–04:50 (marginal, 0.33 h) 72.5° 09:35 5.0 3% 74.8°
2026-07-16 Thu 4 83 3 04:30–04:50 (marginal, 0.33 h) 72.5° 09:30 5.04 9% 89.2°
2026-07-17 Fri 5 99 5 04:20–04:50 (marginal, 0.5 h) 72.5° 09:25 5.08 16% 103.2°
2026-07-18 Sat 6 77 5 03:50–04:05 (marginal, 0.25 h) 72.5° 09:20 5.13 25% 116.8°
2026-07-19 Sun 7 99 7 04:10–04:55 (marginal, 0.75 h) 72.5° 09:15 5.18 35% 129.8°
2026-07-20 Mon 8 96 8 03:40–04:55 (marginal, 1.25 h) 72.5° 09:15 5.22 45% 142.5°
2026-07-21 Tue 11 61 7 04:20–04:55 (marginal, 0.58 h) 72.5° 09:10 5.27 55% 154.8°
2026-07-22 Wed 12 99 12 04:00–04:10 (good, 0.17 h) 72.5° 09:05 5.32 64% 166.9°
2026-07-23 Thu 13 33 4 03:30–04:00 (marginal, 0.5 h) 72.5° 09:00 5.37 73% 178.5°
2026-07-24 Fri 17 0 0 — 72.5° 08:55 5.42 81% 169.2°
2026-07-25 Sat 19 92 17 03:55–04:15 (good, 0.33 h) 72.5° 08:55 5.47 88% 157.4°
2026-07-26 Sun 20 75 15 03:55–04:00 (good, 0.08 h) 72.5° 08:50 5.52 93% 145.5°
2026-07-27 Mon 19 98 19 03:50–04:20 (good, 0.5 h) 72.5° 08:45 5.58 97% 133.6°
2026-07-28 Tue 20 83 17 03:10–04:20 (marginal, 1.17 h) 72.5° 08:40 5.63 100% 121.6°
2026-07-29 Wed 18 100 18 03:50–04:20 (good, 0.5 h) 72.5° 08:40 5.68 100% 109.3°
2026-07-30 Thu 16 100 16 03:55–04:20 (good, 0.42 h) 72.5° 08:35 5.74 98% 97.0°
2026-07-31 Fri 14 100 14 03:00–04:25 (marginal, 1.42 h) 72.5° 08:30 5.79 95% 84.4°
2026-08-01 Sat 12 100 12 03:05–04:25 (marginal, 1.33 h) 72.5° 08:25 5.85 89% 71.6°
2026-08-02 Sun 11 100 11 03:05–04:25 (marginal, 1.33 h) 72.5° 08:20 5.9 82% 58.7°
2026-08-03 Mon 11 100 11 03:00–04:30 (marginal, 1.5 h) 72.5° 08:20 5.96 73% 45.5°
2026-08-04 Tue 11 99 11 02:55–04:30 (marginal, 1.58 h) 72.5° 08:15 6.01 63% 32.0°
2026-08-05 Wed 16 97 16 02:45–04:30 (marginal, 1.75 h) 72.5° 08:10 6.07 52% 18.3°
2026-08-06 Thu 22 97 21 03:35–04:35 (good, 1.0 h) 72.5° 08:05 6.13 40% 4.4°
2026-08-07 Fri 29 100 29 03:10–04:35 (good, 1.42 h) 72.5° 08:00 6.18 30% 10.0°
2026-08-08 Sat 36 63 23 02:25–04:35 (marginal, 2.17 h) 72.5° 08:00 6.24 19% 24.5°
2026-08-09 Sun 44 99 44 02:55–04:40 (good, 1.75 h) 72.5° 07:55 6.3 11% 39.1°
2026-08-10 Mon 49 100 49 02:45–04:40 (good, 1.92 h) 72.5° 07:50 6.35 5% 53.9°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-07-12&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.