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1 year ago in Astronomy , Data Science By Joshna
What has happened to the USNO website?
As an amateur astronomer planning observations, I regularly use the USNO website for sunrise/set times and nautical almanac data. Recently, I've been getting connection timeouts or access denied errors. Is this a known issue perhaps server maintenance, a permanent takedown, or a regional block? Most importantly, where else can I find authoritative astronomical data of the same quality?
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By Reema Answered 1 year ago
I've encountered this issue myself recently. The USNO's public-facing web services occasionally undergo maintenance, security updates, or experience access restrictions, sometimes based on geographic location. It's rarely a permanent takedown. For reliable alternatives, I would recommend the following primary sources immediately: the Her Majesty's Nautical Almanac Office (HMNAO) website or the NASA JPL Horizons System, which is exceptionally powerful for generating precise ephemerides. Many professional astronomers use JPL Horizons as their primary tool. For basic almanac data, timeanddate.com also sources its astronomy data from authoritative institutions and can serve as a good temporary check.
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