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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: 06-29 (10), 06-30 (8), 07-01 (7), 07-02 (6), 07-03 (6) — by astronomy; check the weather when the night is within four days.
2040-06-29astronomy score per night — click a bar for that night2040-07-28
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2040-06-29 Fri 10 — unknown 22:20–23:40 (marginal, 1.33 h) 50.1° 19:20 4.51 66% 164.0°
2040-06-30 Sat 8 — unknown 22:20–23:05 (marginal, 0.75 h) 50.1° 19:15 4.53 55% 177.7°
2040-07-01 Sun 7 — unknown 22:20–23:05 (marginal, 0.75 h) 50.1° 19:10 4.55 45% 169.0°
2040-07-02 Mon 6 — unknown 22:20–23:00 (marginal, 0.67 h) 50.1° 19:05 4.57 34% 156.1°
2040-07-03 Tue 6 — unknown 22:20–22:55 (marginal, 0.58 h) 50.1° 19:05 4.6 25% 143.5°
2040-07-04 Wed 5 — unknown 22:20–22:50 (marginal, 0.5 h) 50.1° 19:00 4.63 17% 131.2°
2040-07-05 Thu 4 — unknown 22:20–22:45 (marginal, 0.42 h) 50.1° 18:55 4.66 10% 119.0°
2040-07-06 Fri 3 — unknown 22:15–22:45 (marginal, 0.5 h) 50.1° 18:50 4.69 5% 107.0°
2040-07-07 Sat 3 — unknown 22:15–22:40 (marginal, 0.42 h) 50.1° 18:45 4.72 2% 95.0°
2040-07-08 Sun 3 — unknown 22:15–22:35 (marginal, 0.33 h) 50.1° 18:45 4.75 0% 83.2°
2040-07-09 Mon 2 — unknown 22:15–22:30 (marginal, 0.25 h) 50.1° 18:40 4.79 0% 71.4°
2040-07-10 Tue 2 — unknown 22:15–22:25 (marginal, 0.17 h) 50.1° 18:35 4.82 2% 59.5°
2040-07-11 Wed 2 — unknown 22:15–22:20 (marginal, 0.08 h) 50.1° 18:30 4.86 6% 47.7°
2040-07-12 Thu 2 — unknown — 50.1° 18:30 4.9 11% 35.7°
2040-07-13 Fri 1 — unknown — 50.1° 18:25 4.94 18% 23.7°
2040-07-14 Sat 1 — unknown — 50.1° 18:20 4.98 26% 11.5°
2040-07-15 Sun 1 — unknown — 50.1° 18:15 5.02 35% 1.1°
2040-07-16 Mon 1 — unknown — 50.1° 18:10 5.07 45% 13.7°
2040-07-17 Tue 0 — unknown — 50.1° 18:10 5.11 56% 26.8°
2040-07-18 Wed 0 — unknown — 50.1° 18:05 5.16 66% 40.3°
2040-07-19 Thu 0 — unknown — 50.1° 18:00 5.21 77% 54.3°
2040-07-20 Fri 0 — unknown — 50.1° 17:55 5.25 86% 68.7°
2040-07-21 Sat 0 — unknown — 50.1° 17:50 5.3 93% 83.5°
2040-07-22 Sun 0 — unknown — 50.1° 17:50 5.35 98% 98.6°
2040-07-23 Mon 0 — unknown — 50.1° 17:45 5.4 100% 113.8°
2040-07-24 Tue 0 — unknown — 50.1° 17:40 5.45 99% 129.1°
2040-07-25 Wed 0 — unknown — 50.1° 17:35 5.5 95% 144.1°
2040-07-26 Thu 0 — unknown — 50.1° 17:35 5.56 88% 158.8°
2040-07-27 Fri 0 — unknown — 50.1° 17:30 5.61 80% 173.1°
2040-07-28 Sat 0 — unknown — 50.1° 17:25 5.66 70% 173.1°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-06-29&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.