The Nikon D810a DSLR camera is currently listed as discontinued or on backorder at the top three US retailers:
The Nikon D810a DSLR camera was specifically designed for astrophotography and it was announced back in February 2015.
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The D810A could be the best low light/high ISO DSLR camera Nikon has ever made *UPDATED*
The Nikon D810a camera is not recommended for general photography