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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: 04-02 (7), 04-03 (7), 03-31 (6), 04-01 (6), 04-04 (6) — by astronomy; check the weather when the night is within four days.
2042-03-31astronomy score per night — click a bar for that night2042-04-29
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2042-03-31 Mon 6 — unknown 21:25–22:05 (marginal, 0.67 h) 72.5° 16:35 8.13 82% 80.6°
2042-04-01 Tue 6 — unknown 21:25–22:05 (marginal, 0.67 h) 72.5° 16:30 8.08 88% 92.5°
2042-04-02 Wed 7 — unknown 21:25–22:05 (marginal, 0.67 h) 72.5° 16:25 8.02 94% 104.4°
2042-04-03 Thu 7 — unknown 21:25–22:00 (marginal, 0.58 h) 72.5° 16:20 7.97 98% 116.2°
2042-04-04 Fri 6 — unknown 21:30–21:55 (marginal, 0.42 h) 72.5° 16:20 7.91 100% 128.1°
2042-04-05 Sat 5 — unknown 21:30–21:50 (marginal, 0.33 h) 72.5° 16:15 7.85 100% 139.9°
2042-04-06 Sun 5 — unknown 21:30–21:50 (marginal, 0.33 h) 72.5° 16:10 7.8 98% 151.8°
2042-04-07 Mon 4 — unknown 21:00–21:15 (marginal, 0.25 h) 72.5° 16:05 7.74 95% 163.8°
2042-04-08 Tue 3 — unknown 21:00–21:15 (marginal, 0.25 h) 72.5° 16:00 7.69 90% 175.8°
2042-04-09 Wed 2 — unknown 21:00–21:10 (marginal, 0.17 h) 72.5° 16:00 7.63 83% 171.6°
2042-04-10 Thu 2 — unknown 21:00–21:05 (marginal, 0.08 h) 72.5° 15:55 7.57 75% 159.2°
2042-04-11 Fri 1 — unknown — 72.5° 15:50 7.52 66% 146.4°
2042-04-12 Sat 1 — unknown — 72.5° 15:45 7.46 56% 133.4°
2042-04-13 Sun 1 — unknown — 72.5° 15:45 7.4 45% 120.0°
2042-04-14 Mon 1 — unknown — 72.5° 15:40 7.34 34% 106.2°
2042-04-15 Tue 0 — unknown — 72.5° 15:35 7.29 24% 92.0°
2042-04-16 Wed 0 — unknown — 72.5° 15:30 7.23 14% 77.5°
2042-04-17 Thu 0 — unknown — 72.5° 15:25 7.17 7% 62.6°
2042-04-18 Fri 0 — unknown — 72.5° 15:25 7.11 2% 47.5°
2042-04-19 Sat 0 — unknown — 72.5° 15:20 7.05 0% 32.3°
2042-04-20 Sun 0 — unknown — 72.5° 15:15 7.0 1% 17.3°
2042-04-21 Mon 0 — unknown — 72.5° 15:10 6.94 5% 2.8°
2042-04-22 Tue 0 — unknown — 72.5° 15:05 6.88 11% 11.9°
2042-04-23 Wed 0 — unknown — 72.5° 15:05 6.82 19% 25.8°
2042-04-24 Thu 0 — unknown — 72.5° 15:00 6.76 28% 39.3°
2042-04-25 Fri 0 — unknown — 72.5° 14:55 6.71 38% 52.3°
2042-04-26 Sat 0 — unknown — 72.5° 14:50 6.65 48% 64.9°
2042-04-27 Sun 0 — unknown — 72.5° 14:50 6.59 58% 77.2°
2042-04-28 Mon 0 — unknown — 72.5° 14:45 6.53 68% 89.3°
2042-04-29 Tue 0 — unknown — 72.5° 14:40 6.47 76% 101.2°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-03-31&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.