I have done a study of the use of dome flats verses super flats for 
the CTIO ccd four amp system.  We have two nights of images to work 
with.  I made a super flat for each night.  I then split the night
into an early half and a late half, making a super flat for each
segment of night.  

To conduct my study I flatened the super flats with the dome flat
of the coresponding night.  This showed bulk envelope difereces 
between the two flats at the 1% level near the corners and at the
0.5% level near the center.  

I then compared the early night super flats with the late night
super flats.  Dividing the early by the late, showed bulk envelope 
diffences between the two flats in the 1% level at both the center
and the corners.  Because of this, we will not be gaining by the use of 
superflats.  The variation of large scale fluctions in each image 
is comperable to the error in using a dome flat.

Therefore we will continue to use dome flats, and recleaning by
superflats will be unnecessay.

Jason Melbourne