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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: 03-21 (93), 03-22 (93), 03-23 (93), 03-24 (93), 04-06 (93) — by astronomy; check the weather when the night is within four days.
2026-03-21astronomy score per night — click a bar for that night2026-04-19
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-03-21 Sat 93 0 0 — 50.2° 00:55 8.67 11% 145.1°
2026-03-22 Sun 93 0 0 — 50.2° 00:50 8.62 19% 130.9°
2026-03-23 Mon 93 0 0 — 50.2° 00:45 8.57 29% 116.7°
2026-03-24 Tue 93 0 0 — 50.2° 00:40 8.51 40% 102.5°
2026-03-25 Wed 89 85 75 22:00–04:00 (good, 6.0 h) 50.2° 00:40 8.46 52% 88.5°
2026-03-26 Thu 84 33 28 20:25–23:00 (marginal, 2.58 h) 50.2° 00:35 8.41 63% 74.7°
2026-03-27 Fri 77 10 8 02:00–03:00 (marginal, 1.0 h) 50.2° 00:30 8.35 73% 61.1°
2026-03-28 Sat 54 6 3 — 50.2° 00:25 8.3 82% 47.6°
2026-03-29 Sun 36 0 0 — 50.2° 01:20 8.25 90% 34.5°
2026-03-30 Mon 27 2 1 — 50.2° 01:20 8.19 95% 21.8°
2026-03-31 Tue 24 4 1 — 50.2° 01:15 8.14 99% 10.5°
2026-04-01 Wed 24 0 0 — 50.2° 01:10 8.08 100% 8.7°
2026-04-02 Thu 30 0 0 — 50.2° 01:05 8.03 99% 19.0°
2026-04-03 Fri 65 0 0 — 50.2° 01:05 7.97 96% 30.7°
2026-04-04 Sat 86 28 24 00:00–01:00 (marginal, 1.0 h) 50.2° 01:00 7.92 92% 42.6°
2026-04-05 Sun 91 73 66 21:30–23:00 (good, 1.5 h) 50.2° 00:55 7.86 86% 54.4°
2026-04-06 Mon 93 73 68 00:00–03:45 (good, 3.75 h) 50.2° 00:50 7.8 79% 66.2°
2026-04-07 Tue 93 38 36 00:00–01:00 (good, 1.0 h) 50.2° 00:45 7.75 71% 77.9°
2026-04-08 Wed 93 35 32 21:35–00:00 (good, 2.42 h) 50.2° 00:45 7.69 62% 89.6°
2026-04-09 Thu 93 59 55 22:00–02:00 (good, 4.0 h) 50.2° 00:40 7.64 53% 101.5°
2026-04-10 Fri 93 0 0 — 50.2° 00:35 7.58 43% 113.5°
2026-04-11 Sat 93 51 48 22:00–02:00 (good, 4.0 h) 50.2° 00:30 7.52 33% 125.8°
2026-04-12 Sun 93 34 32 22:00–00:00 (good, 2.0 h) 50.2° 00:25 7.47 24% 138.3°
2026-04-13 Mon 93 2 2 — 50.2° 00:25 7.41 16% 151.1°
2026-04-14 Tue 93 16 15 02:00–03:00 (good, 1.0 h) 50.2° 00:20 7.35 9% 163.9°
2026-04-15 Wed 93 0 0 — 50.2° 00:15 7.29 3% 172.8°
2026-04-16 Thu 93 6 5 — 50.2° 00:10 7.24 0% 164.3°
2026-04-17 Fri 93 97 90 21:45–04:00 (good, 6.25 h) 50.2° 00:05 7.18 0% 150.6°
2026-04-18 Sat 93 88 82 21:50–03:55 (good, 6.08 h) 50.2° 00:05 7.12 3% 136.1°
2026-04-19 Sun 93 72 67 01:00–03:50 (good, 2.83 h) 50.2° 00:00 7.06 9% 121.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-03-21&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.