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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: 06-28 (8), 06-29 (8), 06-30 (8), 06-27 (7), 07-01 (7) — by astronomy; check the weather when the night is within four days.
2037-06-25astronomy score per night — click a bar for that night2037-07-24
night ofastronomyweatheroverall best windowhighestdark hMoonMoon sep.
2037-06-25 Thu 5 — unknown 23:15–23:45 (marginal, 0.5 h) 50.2° 19:35 4.45 97% 67.8°
2037-06-26 Fri 6 — unknown 23:15–23:45 (marginal, 0.5 h) 50.2° 19:30 4.46 99% 81.1°
2037-06-27 Sat 7 — unknown 23:15–23:50 (marginal, 0.58 h) 50.1° 19:30 4.47 100% 94.1°
2037-06-28 Sun 8 — unknown 23:10–23:45 (marginal, 0.58 h) 50.2° 19:25 4.49 98% 106.8°
2037-06-29 Mon 8 — unknown 22:20–23:05 (marginal, 0.75 h) 50.2° 19:20 4.51 95% 119.4°
2037-06-30 Tue 8 — unknown 22:20–23:35 (marginal, 1.25 h) 50.2° 19:15 4.52 89% 131.6°
2037-07-01 Wed 7 — unknown 22:20–23:05 (marginal, 0.75 h) 50.2° 19:10 4.55 83% 143.7°
2037-07-02 Thu 7 — unknown 22:20–23:00 (marginal, 0.67 h) 50.1° 19:10 4.57 75% 155.6°
2037-07-03 Fri 6 — unknown 22:20–22:55 (marginal, 0.58 h) 50.2° 19:05 4.59 66% 167.5°
2037-07-04 Sat 5 — unknown 22:20–22:50 (marginal, 0.5 h) 50.2° 19:00 4.62 57% 179.4°
2037-07-05 Sun 4 — unknown 22:20–22:50 (marginal, 0.5 h) 50.2° 18:55 4.65 47% 168.7°
2037-07-06 Mon 4 — unknown 22:15–22:45 (marginal, 0.5 h) 50.1° 18:50 4.68 38% 156.6°
2037-07-07 Tue 4 — unknown 22:15–22:40 (marginal, 0.42 h) 50.2° 18:50 4.71 28% 144.3°
2037-07-08 Wed 3 — unknown 22:15–22:35 (marginal, 0.33 h) 50.2° 18:45 4.74 20% 131.7°
2037-07-09 Thu 3 — unknown 22:15–22:30 (marginal, 0.25 h) 50.2° 18:40 4.78 12% 118.7°
2037-07-10 Fri 2 — unknown 22:15–22:30 (marginal, 0.25 h) 50.2° 18:35 4.81 6% 105.3°
2037-07-11 Sat 2 — unknown 22:15–22:25 (marginal, 0.17 h) 50.1° 18:35 4.85 2% 91.5°
2037-07-12 Sun 2 — unknown 22:15–22:20 (marginal, 0.08 h) 50.2° 18:30 4.89 0% 77.4°
2037-07-13 Mon 2 — unknown — 50.2° 18:25 4.93 1% 62.9°
2037-07-14 Tue 2 — unknown 22:10–22:15 (marginal, 0.08 h) 50.2° 18:20 4.97 5% 48.3°
2037-07-15 Wed 1 — unknown — 50.2° 18:15 5.01 11% 33.7°
2037-07-16 Thu 1 — unknown — 50.1° 18:15 5.06 19% 19.1°
2037-07-17 Fri 1 — unknown — 50.2° 18:10 5.1 29% 4.6°
2037-07-18 Sat 0 — unknown — 50.2° 18:05 5.15 40% 9.7°
2037-07-19 Sun 0 — unknown — 50.2° 18:00 5.19 52% 23.8°
2037-07-20 Mon 0 — unknown — 50.1° 17:55 5.24 63% 37.6°
2037-07-21 Tue 0 — unknown — 50.2° 17:55 5.29 73% 51.1°
2037-07-22 Wed 0 — unknown — 50.2° 17:50 5.34 82% 64.4°
2037-07-23 Thu 0 — unknown — 50.2° 17:45 5.39 90% 77.5°
2037-07-24 Fri 0 — unknown — 50.2° 17:40 5.44 95% 90.4°

Download: CSV · JSON


💡 API
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-06-25&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.