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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 HD 189733: 05-11 (86), 05-12 (86), 05-13 (86), 05-10 (85), 05-09 (83) — by astronomy; check the weather when the night is within four days.
2027-04-14astronomy score per night — click a bar for that night2027-05-13
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2027-04-14 Wed 57 — unknown 02:55–05:05 (good, 2.17 h) 71.1° 07:50 7.36 61% 136.9°
2027-04-15 Thu 56 — unknown 02:50–05:00 (good, 2.17 h) 71.1° 07:45 7.31 72% 136.5°
2027-04-16 Fri 56 — unknown 02:50–05:00 (good, 2.17 h) 71.1° 07:45 7.25 81% 132.7°
2027-04-17 Sat 52 — unknown 02:45–05:00 (good, 2.25 h) 71.1° 07:40 7.19 89% 126.2°
2027-04-18 Sun 50 — unknown 02:45–04:55 (good, 2.17 h) 71.1° 07:35 7.13 95% 118.0°
2027-04-19 Mon 46 — unknown 02:45–04:55 (good, 2.17 h) 71.1° 07:30 7.08 99% 108.9°
2027-04-20 Tue 41 — unknown 02:50–04:55 (good, 2.08 h) 71.1° 07:25 7.02 100% 99.3°
2027-04-21 Wed 37 — unknown 03:00–04:50 (good, 1.83 h) 71.1° 07:25 6.96 99% 89.7°
2027-04-22 Thu 34 — unknown 03:25–04:50 (good, 1.42 h) 71.1° 07:20 6.9 96% 80.3°
2027-04-23 Fri 32 — unknown 03:35–04:45 (good, 1.17 h) 71.1° 07:15 6.84 90% 71.3°
2027-04-24 Sat 32 — unknown 03:35–04:45 (good, 1.17 h) 71.1° 07:10 6.78 84% 63.0°
2027-04-25 Sun 33 — unknown 03:10–04:45 (good, 1.58 h) 71.1° 07:05 6.73 76% 55.6°
2027-04-26 Mon 36 — unknown 02:25–04:40 (good, 2.25 h) 71.1° 07:05 6.67 68% 49.4°
2027-04-27 Tue 49 — unknown 02:00–04:40 (good, 2.67 h) 71.1° 07:00 6.61 59% 45.0°
2027-04-28 Wed 54 — unknown 01:55–04:35 (good, 2.67 h) 71.1° 06:55 6.55 49% 42.9°
2027-04-29 Thu 60 — unknown 01:50–04:35 (good, 2.75 h) 71.1° 06:50 6.49 40% 43.3°
2027-04-30 Fri 66 — unknown 01:45–04:35 (good, 2.83 h) 71.1° 06:50 6.43 31% 46.3°
2027-05-01 Sat 71 — unknown 01:40–04:30 (good, 2.83 h) 71.1° 06:45 6.38 22% 51.6°
2027-05-02 Sun 76 — unknown 01:40–04:30 (good, 2.83 h) 71.1° 06:40 6.32 14% 58.6°
2027-05-03 Mon 78 — unknown 01:35–04:30 (good, 2.92 h) 71.1° 06:35 6.26 8% 67.0°
2027-05-04 Tue 77 — unknown 01:30–04:25 (good, 2.92 h) 71.1° 06:30 6.2 3% 76.4°
2027-05-05 Wed 79 — unknown 01:25–04:25 (good, 3.0 h) 71.1° 06:30 6.15 0% 86.3°
2027-05-06 Thu 81 — unknown 01:25–04:25 (good, 3.0 h) 71.1° 06:25 6.09 0% 96.6°
2027-05-07 Fri 82 — unknown 01:20–04:20 (good, 3.0 h) 71.1° 06:20 6.03 3% 106.9°
2027-05-08 Sat 82 — unknown 01:15–04:20 (good, 3.08 h) 71.1° 06:15 5.98 8% 116.8°
2027-05-09 Sun 83 — unknown 01:10–04:15 (good, 3.08 h) 71.1° 06:10 5.92 16% 125.6°
2027-05-10 Mon 85 — unknown 01:05–04:15 (good, 3.17 h) 71.1° 06:10 5.86 25% 132.5°
2027-05-11 Tue 86 — unknown 01:05–04:15 (good, 3.17 h) 71.1° 06:05 5.81 36% 136.7°
2027-05-12 Wed 86 — unknown 01:05–04:10 (good, 3.08 h) 71.1° 06:00 5.75 47% 137.2°
2027-05-13 Thu 86 — unknown 01:00–04:10 (good, 3.17 h) 71.1° 05:55 5.7 58% 134.1°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-04-14&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.