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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: 03-06 (55), 03-07 (54), 03-05 (53), 03-08 (52), 03-09 (51) — by astronomy; check the weather when the night is within four days.
2026-02-25astronomy score per night — click a bar for that night2026-03-26
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-02-25 Wed 19 95 18 19:40–23:00 (marginal, 3.33 h) 42.9° 19:35 9.83 66% 33.8°
2026-02-26 Thu 14 94 13 19:45–22:35 (marginal, 2.83 h) 42.9° 19:30 9.78 76% 37.1°
2026-02-27 Fri 13 55 7 19:45–21:00 (marginal, 1.25 h) 42.9° 19:25 9.74 85% 44.2°
2026-02-28 Sat 14 100 14 19:45–22:25 (marginal, 2.67 h) 42.9° 19:25 9.69 92% 53.5°
2026-03-01 Sun 19 100 19 19:45–22:35 (marginal, 2.83 h) 42.9° 19:20 9.65 97% 64.0°
2026-03-02 Mon 25 26 7 20:00–20:25 (marginal, 0.42 h) 42.9° 19:15 9.6 100% 74.9°
2026-03-03 Tue 32 0 0 — 42.9° 19:10 9.56 100% 86.0°
2026-03-04 Wed 41 1 0 — 42.9° 19:10 9.51 98% 96.8°
2026-03-05 Thu 53 11 6 22:00–22:25 (marginal, 0.42 h) 42.9° 19:05 9.46 94% 107.3°
2026-03-06 Fri 55 67 37 19:50–21:00 (good, 1.17 h) 42.9° 19:00 9.41 88% 117.3°
2026-03-07 Sat 54 79 43 19:55–20:30 (good, 0.58 h) 42.9° 18:55 9.37 81% 126.5°
2026-03-08 Sun 52 59 30 21:00–21:45 (good, 0.75 h) 42.9° 18:50 9.32 72% 134.7°
2026-03-09 Mon 51 49 25 21:00–22:40 (marginal, 1.67 h) 42.9° 18:50 9.27 64% 141.2°
2026-03-10 Tue 49 99 49 19:55–22:00 (good, 2.08 h) 42.9° 18:45 9.22 54% 145.3°
2026-03-11 Wed 47 23 11 20:00–21:00 (marginal, 1.0 h) 42.9° 18:40 9.17 45% 146.1°
2026-03-12 Thu 45 0 0 — 42.9° 18:35 9.13 36% 143.3°
2026-03-13 Fri 43 100 43 20:00–21:50 (good, 1.83 h) 42.9° 18:30 9.08 27% 137.5°
2026-03-14 Sat 42 100 42 20:00–21:50 (good, 1.83 h) 42.9° 18:30 9.03 18% 129.6°
2026-03-15 Sun 40 97 39 20:05–21:40 (good, 1.58 h) 42.9° 18:25 8.98 11% 120.3°
2026-03-16 Mon 38 2 1 — 42.9° 18:20 8.93 5% 110.0°
2026-03-17 Tue 37 0 0 — 42.9° 18:15 8.88 2% 98.9°
2026-03-18 Wed 36 0 0 — 42.9° 18:15 8.82 0% 87.5°
2026-03-19 Thu 33 0 0 — 42.9° 18:10 8.77 1% 75.8°
2026-03-20 Fri 31 0 0 — 42.9° 18:05 8.72 5% 64.3°
2026-03-21 Sat 28 0 0 — 42.9° 18:00 8.67 11% 53.4°
2026-03-22 Sun 23 0 0 — 42.9° 17:55 8.62 19% 43.7°
2026-03-23 Mon 18 0 0 — 42.9° 17:55 8.57 29% 36.7°
2026-03-24 Tue 13 0 0 — 42.9° 17:50 8.51 40% 33.8°
2026-03-25 Wed 9 77 7 20:15–21:00 (marginal, 0.75 h) 42.9° 17:45 8.46 52% 35.9°
2026-03-26 Thu 7 90 6 20:15–21:10 (marginal, 0.92 h) 42.9° 17:40 8.41 63% 42.2°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-02-25&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.