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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: 04-02 (10), 03-30 (9), 03-31 (9), 04-01 (9), 03-29 (8) — by astronomy; check the weather when the night is within four days.
2037-03-26astronomy score per night — click a bar for that night2037-04-24
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2037-03-26 Thu 6 — unknown 20:15–21:05 (marginal, 0.83 h) 42.9° 17:40 8.39 73% 48.8°
2037-03-27 Fri 6 — unknown 20:20–21:05 (marginal, 0.75 h) 42.9° 17:35 8.34 83% 61.2°
2037-03-28 Sat 7 — unknown 20:20–21:05 (marginal, 0.75 h) 42.9° 17:35 8.28 91% 74.3°
2037-03-29 Sun 8 — unknown 21:20–22:10 (marginal, 0.83 h) 42.9° 18:30 8.23 97% 87.9°
2037-03-30 Mon 9 — unknown 21:20–22:15 (marginal, 0.92 h) 42.9° 18:25 8.17 100% 101.6°
2037-03-31 Tue 9 — unknown 20:50–22:10 (marginal, 1.33 h) 42.9° 18:20 8.12 99% 115.0°
2037-04-01 Wed 9 — unknown 21:25–21:30 (good, 0.08 h) 42.9° 18:15 8.06 96% 127.7°
2037-04-02 Thu 10 — unknown 21:25–21:30 (good, 0.08 h) 42.9° 18:15 8.01 91% 139.3°
2037-04-03 Fri 7 — unknown 20:55–22:00 (marginal, 1.08 h) 42.9° 18:10 7.95 84% 148.8°
2037-04-04 Sat 6 — unknown 21:30–21:55 (marginal, 0.42 h) 42.9° 18:05 7.9 75% 154.2°
2037-04-05 Sun 5 — unknown 21:30–21:50 (marginal, 0.33 h) 42.9° 18:00 7.84 65% 153.8°
2037-04-06 Mon 4 — unknown 21:30–21:45 (marginal, 0.25 h) 42.9° 17:55 7.79 55% 148.2°
2037-04-07 Tue 3 — unknown 21:35–21:45 (marginal, 0.17 h) 42.9° 17:55 7.73 46% 139.8°
2037-04-08 Wed 3 — unknown 21:00–21:10 (marginal, 0.17 h) 42.9° 17:50 7.67 36% 130.2°
2037-04-09 Thu 2 — unknown 21:00–21:05 (marginal, 0.08 h) 42.9° 17:45 7.62 27% 120.1°
2037-04-10 Fri 1 — unknown — 42.9° 17:40 7.56 19% 109.6°
2037-04-11 Sat 1 — unknown — 42.9° 17:40 7.5 12% 99.0°
2037-04-12 Sun 1 — unknown — 42.9° 17:35 7.45 7% 88.3°
2037-04-13 Mon 1 — unknown — 42.9° 17:30 7.39 3% 77.5°
2037-04-14 Tue 0 — unknown — 42.9° 17:25 7.33 1% 66.8°
2037-04-15 Wed 0 — unknown — 42.9° 17:20 7.27 0% 56.1°
2037-04-16 Thu 0 — unknown — 42.9° 17:20 7.22 2% 45.7°
2037-04-17 Fri 0 — unknown — 42.9° 17:15 7.16 5% 36.3°
2037-04-18 Sat 0 — unknown — 42.9° 17:10 7.1 11% 28.7°
2037-04-19 Sun 0 — unknown — 42.9° 17:05 7.04 18% 25.4°
2037-04-20 Mon 0 — unknown — 42.9° 17:00 6.98 27% 28.0°
2037-04-21 Tue 0 — unknown — 42.9° 17:00 6.93 37% 35.5°
2037-04-22 Wed 0 — unknown — 42.9° 16:55 6.87 48% 45.7°
2037-04-23 Thu 0 — unknown — 42.9° 16:50 6.81 59% 57.4°
2037-04-24 Fri 0 — unknown — 42.9° 16:45 6.75 70% 69.9°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-03-26&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.