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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: 06-16 (28), 06-17 (26), 06-18 (22), 06-19 (18), 06-20 (14) — by astronomy; check the weather when the night is within four days.
2026-06-16astronomy score per night — click a bar for that night2026-07-15
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2026-06-16 Tue 28 0 0 — 50.2° 20:10 4.44 5% 74.2°
2026-06-17 Wed 26 0 0 — 50.2° 20:10 4.43 12% 59.6°
2026-06-18 Thu 22 81 18 23:10–23:35 (good, 0.42 h) 50.2° 20:05 4.43 20% 45.4°
2026-06-19 Fri 18 83 15 23:10–00:20 (marginal, 1.17 h) 50.2° 20:00 4.42 30% 31.8°
2026-06-20 Sat 14 94 13 23:15–23:20 (good, 0.08 h) 50.2° 19:55 4.42 40% 19.1°
2026-06-21 Sun 11 98 11 23:15–00:10 (marginal, 0.92 h) 50.2° 19:50 4.42 50% 8.9°
2026-06-22 Mon 8 90 7 23:15–00:00 (marginal, 0.75 h) 50.2° 19:50 4.42 60% 11.1°
2026-06-23 Tue 6 30 2 — 50.2° 19:45 4.43 70% 21.7°
2026-06-24 Wed 5 67 3 23:15–23:35 (marginal, 0.33 h) 50.2° 19:40 4.43 78% 33.3°
2026-06-25 Thu 5 81 4 23:15–23:35 (marginal, 0.33 h) 50.2° 19:35 4.44 86% 45.1°
2026-06-26 Fri 5 88 4 23:15–23:40 (marginal, 0.42 h) 50.2° 19:30 4.45 92% 56.8°
2026-06-27 Sat 5 86 4 23:15–23:35 (marginal, 0.33 h) 50.2° 19:30 4.47 96% 68.5°
2026-06-28 Sun 5 100 5 23:15–23:40 (marginal, 0.42 h) 50.2° 19:25 4.48 99% 80.2°
2026-06-29 Mon 6 89 5 23:10–23:40 (marginal, 0.5 h) 50.2° 19:20 4.5 100% 91.9°
2026-06-30 Tue 6 98 6 22:20–22:55 (marginal, 0.58 h) 50.2° 19:15 4.52 99% 103.7°
2026-07-01 Wed 7 23 2 — 50.2° 19:15 4.54 96% 115.7°
2026-07-02 Thu 6 62 4 23:10–23:15 (marginal, 0.08 h) 50.2° 19:10 4.56 92% 127.7°
2026-07-03 Fri 6 7 0 — 50.2° 19:05 4.58 86% 139.8°
2026-07-04 Sat 5 57 3 — 50.2° 19:00 4.61 78% 151.9°
2026-07-05 Sun 4 88 4 22:20–22:35 (marginal, 0.25 h) 50.2° 18:55 4.64 70% 163.7°
2026-07-06 Mon 4 94 4 22:20–22:40 (marginal, 0.33 h) 50.2° 18:55 4.67 59% 172.2°
2026-07-07 Tue 3 84 3 22:15–22:20 (marginal, 0.08 h) 50.2° 18:50 4.7 49% 165.7°
2026-07-08 Wed 3 0 0 — 50.2° 18:45 4.73 38% 153.1°
2026-07-09 Thu 3 79 2 — 50.2° 18:40 4.76 27% 139.4°
2026-07-10 Fri 2 64 1 — 50.2° 18:35 4.8 17% 125.2°
2026-07-11 Sat 2 100 2 22:15–22:25 (marginal, 0.17 h) 50.2° 18:35 4.84 9% 110.5°
2026-07-12 Sun 2 78 2 — 50.2° 18:30 4.87 3% 95.7°
2026-07-13 Mon 2 87 2 — 50.2° 18:25 4.91 0% 80.7°
2026-07-14 Tue 2 90 2 — 50.2° 18:20 4.96 0% 65.8°
2026-07-15 Wed 1 20 0 — 50.2° 18:20 5.0 3% 51.3°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-06-16&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.