[ATM] The Hubble mirror goof up.

[Mark Holm <mdholm@telerama.com>]

I remember there was a rather detailed and complete analysis of the 
error presented in a Sky and Telescope article.  From reading that 
several years ago, I do remember it seems the big screw up was not doing 
a sanity check by another method.

The nuller they used was very precisely made and it was generally agreed 
that it should be the one used for final figuring.  It had the advantage 
that each of it's optical components could be tested to higher precision 
than the elements of the other nuller.  The technical screw up was a 
matter of spacing between components of the primary nuller, a mechanical 
error.  The second nuller might not have been as precise, but it surely 
would have shown the gross error introduced by the bad spacing in the 
primary nuller.  Many have said, I do not know if it is true, that the 
error could also have been detected by a zonal Foucault test.

-- 
Mark Holm
mdholm@telerama.com


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