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Hubble Space Telescope
FOC Instrument Science Report #095

FOC Instrument Science Report #095       October 29, 1996

"FOC f/48 Geometric Correction"
by M. Voit and W. Hack

Abstract excerpted from the report:

This report summarizes our program to correct the
geometric distortion of the f/48 imaging camera. We
used several offset observations of 47 Tuc to correct
the 256zx1024 format, and this correction model was
then used to determine the distortion of the 512zx1024
format. The description of the geometric correction
procedure presented here can serve as a primer for future
determinations of FOC geometric distortion. Because 
the offsets used to correct the f/48 distortion were
highly symmetric, spurious systematic 2-D modes crept
into the correction algorithm when we use too fine a
grid for the spline model correction. With the newly
corrected imaging format, we should be able to place
targets directly into the f/48 slit in a single slew
following the initial acquisition.