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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 Great Orion Nebula: 03-26 (13), 03-27 (10), 03-28 (7), 03-29 (6), 03-30 (5) — by astronomy; check the weather when the night is within four days.
2042-03-26astronomy score per night — click a bar for that night2042-04-24
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2042-03-26 Wed 13 — unknown 20:15–20:30 (good, 0.25 h) 42.9° 17:40 8.4 34% 33.2°
2042-03-27 Thu 10 — unknown 20:20–21:25 (marginal, 1.08 h) 42.9° 17:40 8.35 44% 34.2°
2042-03-28 Fri 7 — unknown 20:20–21:10 (marginal, 0.83 h) 42.9° 17:35 8.29 55% 39.1°
2042-03-29 Sat 6 — unknown 20:20–21:00 (marginal, 0.67 h) 42.9° 17:30 8.24 64% 46.6°
2042-03-30 Sun 5 — unknown 21:20–21:55 (marginal, 0.58 h) 42.9° 18:25 8.18 74% 55.3°
2042-03-31 Mon 4 — unknown 21:25–21:50 (marginal, 0.42 h) 42.9° 18:20 8.13 82% 64.7°
2042-04-01 Tue 4 — unknown 21:25–21:55 (marginal, 0.5 h) 42.9° 18:20 8.08 88% 74.4°
2042-04-02 Wed 4 — unknown 21:25–21:55 (marginal, 0.5 h) 42.9° 18:15 8.02 94% 84.3°
2042-04-03 Thu 5 — unknown 21:25–22:00 (marginal, 0.58 h) 42.9° 18:10 7.97 98% 94.2°
2042-04-04 Fri 4 — unknown 21:30–21:55 (marginal, 0.42 h) 42.9° 18:05 7.91 100% 104.1°
2042-04-05 Sat 4 — unknown 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.85 100% 113.8°
2042-04-06 Sun 4 — unknown 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.8 98% 123.1°
2042-04-07 Mon 3 — unknown 21:00–21:15 (marginal, 0.25 h) 42.9° 17:55 7.74 95% 131.8°
2042-04-08 Tue 3 — unknown 21:00–21:10 (marginal, 0.17 h) 42.9° 17:50 7.69 90% 139.3°
2042-04-09 Wed 2 — unknown 21:00–21:05 (marginal, 0.08 h) 42.9° 17:45 7.63 83% 144.8°
2042-04-10 Thu 2 — unknown — 42.9° 17:45 7.57 75% 147.0°
2042-04-11 Fri 1 — unknown — 42.9° 17:40 7.52 66% 145.0°
2042-04-12 Sat 1 — unknown — 42.9° 17:35 7.46 56% 139.2°
2042-04-13 Sun 1 — unknown — 42.9° 17:30 7.4 45% 130.8°
2042-04-14 Mon 1 — unknown — 42.9° 17:25 7.34 34% 120.7°
2042-04-15 Tue 0 — unknown — 42.9° 17:25 7.29 24% 109.3°
2042-04-16 Wed 0 — unknown — 42.9° 17:20 7.23 14% 97.3°
2042-04-17 Thu 0 — unknown — 42.9° 17:15 7.17 7% 84.8°
2042-04-18 Fri 0 — unknown — 42.9° 17:10 7.11 2% 72.3°
2042-04-19 Sat 0 — unknown — 42.9° 17:05 7.05 0% 60.1°
2042-04-20 Sun 0 — unknown — 42.9° 17:05 7.0 1% 49.0°
2042-04-21 Mon 0 — unknown — 42.9° 17:00 6.94 5% 39.9°
2042-04-22 Tue 0 — unknown — 42.9° 16:55 6.88 11% 34.2°
2042-04-23 Wed 0 — unknown — 42.9° 16:50 6.82 19% 33.3°
2042-04-24 Thu 0 — unknown — 42.9° 16:45 6.76 28% 37.1°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-03-26&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.