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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 3C 273: 06-30 (9), 07-01 (7), 07-02 (6), 07-03 (4), 07-04 (3) — by astronomy; check the weather when the night is within four days.
2041-06-30astronomy score per night — click a bar for that night2041-07-29
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2041-06-30 Sun 9 — unknown 22:20–23:35 (marginal, 1.25 h) 50.1° 19:15 4.52 6% 58.3°
2041-07-01 Mon 7 — unknown 22:20–23:00 (marginal, 0.67 h) 50.1° 19:10 4.55 11% 46.3°
2041-07-02 Tue 6 — unknown 22:20–22:50 (marginal, 0.5 h) 50.1° 19:10 4.57 18% 34.4°
2041-07-03 Wed 4 — unknown 22:20–22:45 (marginal, 0.42 h) 50.1° 19:05 4.59 26% 22.6°
2041-07-04 Thu 3 — unknown 23:10–23:20 (marginal, 0.17 h) 50.1° 19:00 4.62 34% 10.9°
2041-07-05 Fri 2 — unknown 23:10–23:15 (marginal, 0.08 h) 50.1° 18:55 4.65 44% 2.1°
2041-07-06 Sat 2 — unknown — 50.1° 18:50 4.68 53% 13.4°
2041-07-07 Sun 2 — unknown — 50.1° 18:50 4.71 63% 25.8°
2041-07-08 Mon 1 — unknown — 50.1° 18:45 4.74 73% 38.5°
2041-07-09 Tue 1 — unknown — 50.1° 18:40 4.78 82% 51.6°
2041-07-10 Wed 1 — unknown — 50.1° 18:35 4.81 89% 65.2°
2041-07-11 Thu 1 — unknown — 50.1° 18:35 4.85 95% 79.2°
2041-07-12 Fri 1 — unknown — 50.1° 18:30 4.89 99% 93.6°
2041-07-13 Sat 1 — unknown — 50.1° 18:25 4.93 100% 108.3°
2041-07-14 Sun 1 — unknown — 50.1° 18:20 4.97 98% 123.2°
2041-07-15 Mon 1 — unknown — 50.1° 18:15 5.01 93% 138.1°
2041-07-16 Tue 1 — unknown — 50.1° 18:15 5.06 86% 153.0°
2041-07-17 Wed 1 — unknown — 50.1° 18:10 5.1 77% 167.6°
2041-07-18 Thu 1 — unknown — 50.1° 18:05 5.15 66% 177.3°
2041-07-19 Fri 1 — unknown — 50.1° 18:00 5.19 55% 163.8°
2041-07-20 Sat 1 — unknown — 50.1° 17:55 5.24 44% 150.1°
2041-07-21 Sun 1 — unknown — 50.1° 17:55 5.29 34% 136.7°
2041-07-22 Mon 0 — unknown — 50.1° 17:50 5.34 24% 123.7°
2041-07-23 Tue 0 — unknown — 50.1° 17:45 5.39 16% 110.9°
2041-07-24 Wed 0 — unknown — 50.1° 17:40 5.44 9% 98.3°
2041-07-25 Thu 0 — unknown — 50.1° 17:40 5.49 4% 85.9°
2041-07-26 Fri 0 — unknown — 50.1° 17:35 5.54 1% 73.6°
2041-07-27 Sat 0 — unknown — 50.1° 17:30 5.6 0% 61.5°
2041-07-28 Sun 0 — unknown — 50.1° 17:25 5.65 1% 49.6°
2041-07-29 Mon 0 — unknown — 50.1° 17:20 5.7 3% 37.7°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-06-30&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.