Did you recheck the hole as I wonder why it read on the very top right, maybe there was a silver quarter there too. This is one thing that has me wondering on the Explorer if you ever tried it. A silver quarter will be on the very top right (30 digital)and silver half will read down from the top a little, but all the way to the right (28 digital) and the silver dollar will read down slightly more so there is about 1/4 inch down from the top, but still all the way to the right (27 digital) The signal is not quite as high pitched with of that of a silver quarter. It is odd after the quarter, the half and silver dollars will read lower on the screen and lower in pitch both air test and in the ground (havent found a silver dollar with the Explorer yet, but I got several halfs and quarters that read the same in the ground as they do in air test). This is why I ask if you rechecked the hole again to be sure there wasnt another coin there too as all the excitement I can see not checking the hole again.
Great find though and the first silver dollar will be something you will never forget, My first one in 1977 is till as fresh in my mind as it was that day I found it.
Rick