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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: 01-18 (93), 01-19 (93), 01-20 (93), 01-21 (93), 01-22 (93) — by astronomy; check the weather when the night is within four days.
2026-01-18astronomy score per night — click a bar for that night2026-02-16
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-01-18 Sun 93 0 0 — 50.2° 04:55 11.16 0% 114.4°
2026-01-19 Mon 93 98 91 01:15–06:10 (good, 4.92 h) 50.2° 04:55 11.13 1% 126.9°
2026-01-20 Tue 93 5 5 — 50.2° 04:50 11.11 5% 139.6°
2026-01-21 Wed 93 0 0 — 50.2° 04:45 11.08 10% 152.3°
2026-01-22 Thu 93 0 0 — 50.2° 04:40 11.06 17% 164.7°
2026-01-23 Fri 93 48 45 02:00–04:00 (good, 2.0 h) 50.2° 04:40 11.03 26% 172.9°
2026-01-24 Sat 93 0 0 — 50.2° 04:35 11.0 36% 164.8°
2026-01-25 Sun 93 0 0 — 50.2° 04:30 10.97 47% 151.9°
2026-01-26 Mon 93 0 0 — 50.2° 04:25 10.94 58% 138.1°
2026-01-27 Tue 93 8 7 06:00–06:05 (marginal, 0.08 h) 50.2° 04:20 10.91 69% 124.1°
2026-01-28 Wed 93 0 0 — 50.2° 04:20 10.88 80% 109.8°
2026-01-29 Thu 90 0 0 — 50.2° 04:15 10.85 88% 95.4°
2026-01-30 Fri 65 0 0 — 50.2° 04:10 10.82 95% 81.0°
2026-01-31 Sat 47 0 0 — 50.2° 04:05 10.79 99% 66.6°
2026-02-01 Sun 32 0 0 — 50.2° 04:00 10.76 100% 52.5°
2026-02-02 Mon 22 0 0 — 50.2° 04:00 10.72 99% 38.7°
2026-02-03 Tue 19 0 0 — 50.2° 03:55 10.69 95% 25.5°
2026-02-04 Wed 23 0 0 — 50.2° 03:50 10.66 89% 13.3°
2026-02-05 Thu 30 0 0 — 50.2° 03:45 10.62 82% 7.3°
2026-02-06 Fri 42 0 0 — 50.2° 03:45 10.59 74% 15.9°
2026-02-07 Sat 66 26 17 00:00–02:00 (marginal, 2.0 h) 50.2° 03:40 10.55 65% 27.3°
2026-02-08 Sun 85 4 3 23:55–00:00 (marginal, 0.08 h) 50.2° 03:35 10.51 56% 39.0°
2026-02-09 Mon 91 0 0 — 50.2° 03:30 10.48 46% 50.7°
2026-02-10 Tue 93 0 0 — 50.2° 03:25 10.44 37% 62.4°
2026-02-11 Wed 93 0 0 — 50.2° 03:25 10.4 28% 74.1°
2026-02-12 Thu 93 0 0 — 50.2° 03:20 10.36 20% 86.0°
2026-02-13 Fri 93 13 12 05:00–05:45 (marginal, 0.75 h) 50.2° 03:15 10.32 13% 98.0°
2026-02-14 Sat 93 9 8 23:05–00:00 (marginal, 0.92 h) 50.2° 03:10 10.29 7% 110.3°
2026-02-15 Sun 93 52 49 03:00–05:45 (good, 2.75 h) 50.2° 03:05 10.25 3% 122.8°
2026-02-16 Mon 93 0 0 — 50.2° 03:05 10.21 0% 135.6°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-01-18&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.