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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: 01-02 (93), 01-03 (93), 01-04 (93), 01-05 (93), 01-06 (93) — by astronomy; check the weather when the night is within four days.
2027-12-16astronomy score per night — click a bar for that night2028-01-14
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2027-12-16 Thu 18 — unknown 03:20–06:05 (marginal, 2.75 h) 50.2° 07:10 11.5 86% 57.2°
2027-12-17 Fri 17 — unknown 03:15–06:05 (marginal, 2.83 h) 50.2° 07:05 11.5 77% 42.9°
2027-12-18 Sat 19 — unknown 03:05–06:05 (marginal, 3.0 h) 50.2° 07:00 11.5 66% 29.1°
2027-12-19 Sun 28 — unknown 02:50–06:05 (marginal, 3.25 h) 50.2° 06:55 11.51 55% 16.5°
2027-12-20 Mon 37 — unknown 03:35–06:05 (good, 2.5 h) 50.2° 06:55 11.51 44% 9.4°
2027-12-21 Tue 48 — unknown 03:20–06:05 (good, 2.75 h) 50.2° 06:50 11.51 33% 16.8°
2027-12-22 Wed 59 — unknown 03:00–06:05 (good, 3.08 h) 50.2° 06:45 11.51 24% 28.8°
2027-12-23 Thu 71 — unknown 02:55–06:10 (good, 3.25 h) 50.2° 06:40 11.51 15% 41.4°
2027-12-24 Fri 78 — unknown 02:50–06:10 (good, 3.33 h) 50.2° 06:40 11.5 8% 54.1°
2027-12-25 Sat 81 — unknown 02:45–06:10 (good, 3.42 h) 50.2° 06:35 11.5 4% 66.6°
2027-12-26 Sun 82 — unknown 02:45–06:10 (good, 3.42 h) 50.2° 06:30 11.5 1% 79.0°
2027-12-27 Mon 84 — unknown 02:40–06:10 (good, 3.5 h) 50.2° 06:25 11.49 0% 91.2°
2027-12-28 Tue 86 — unknown 02:35–06:10 (good, 3.58 h) 50.2° 06:20 11.49 1% 103.3°
2027-12-29 Wed 87 — unknown 02:30–06:10 (good, 3.67 h) 50.2° 06:20 11.48 4% 115.2°
2027-12-30 Thu 88 — unknown 02:25–06:10 (good, 3.75 h) 50.2° 06:15 11.47 9% 126.9°
2027-12-31 Fri 90 — unknown 02:25–06:10 (good, 3.75 h) 50.2° 06:10 11.46 15% 138.4°
2028-01-01 Sat 91 — unknown 02:20–06:10 (good, 3.83 h) 50.2° 06:05 11.45 22% 149.8°
2028-01-02 Sun 93 — unknown 02:15–06:10 (good, 3.92 h) 50.2° 06:00 11.44 30% 160.6°
2028-01-03 Mon 93 — unknown 02:10–06:10 (good, 4.0 h) 50.2° 06:00 11.43 39% 169.3°
2028-01-04 Tue 93 — unknown 02:05–06:10 (good, 4.08 h) 50.2° 05:55 11.42 49% 168.2°
2028-01-05 Wed 93 — unknown 02:05–06:10 (good, 4.08 h) 50.2° 05:50 11.41 58% 158.5°
2028-01-06 Thu 93 — unknown 02:05–06:10 (good, 4.08 h) 50.2° 05:45 11.4 68% 146.6°
2028-01-07 Fri 93 — unknown 02:05–06:10 (good, 4.08 h) 50.2° 05:45 11.38 78% 133.9°
2028-01-08 Sat 93 — unknown 02:00–06:10 (good, 4.17 h) 50.2° 05:40 11.37 86% 120.6°
2028-01-09 Sun 77 — unknown 02:10–06:10 (good, 4.0 h) 50.2° 05:35 11.35 93% 106.8°
2028-01-10 Mon 61 — unknown 03:00–06:10 (good, 3.17 h) 50.2° 05:30 11.33 98% 92.5°
2028-01-11 Tue 46 — unknown 04:50–06:10 (good, 1.33 h) 50.2° 05:25 11.31 100% 77.8°
2028-01-12 Wed 33 — unknown 01:45–06:10 (marginal, 4.42 h) 50.2° 05:25 11.3 99% 63.0°
2028-01-13 Thu 24 — unknown 01:55–06:10 (marginal, 4.25 h) 50.2° 05:20 11.28 95% 48.2°
2028-01-14 Fri 19 — unknown 01:55–06:10 (marginal, 4.25 h) 50.2° 05:15 11.26 89% 33.7°

Download: CSV · JSON

💡 API 
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-12-16&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.