The files x_daophot.e.redhat and x_daophot.e.ssun are the RedHat and
Solaris executables for V2.12.3.  The changes are a more stable matrix
inversion routine and a bug fix for a floating divide by zero error.
The executable can replace the standard executable but it requires
installation of a new parameter file (along with a user "unlearn allstar")
to pick up a new backward compatibility version parameter.

% cd $iraf/noao/bin.<arch>
% mv x_daophot.e x_daophot.eBAK
% mv <path>/x_daophot.e.<arch> x_daophot.e
% cd $iraf/noao/digiphot/daophot
% mv <path>/allstar.par.v2123 allstar.par

where <arch> is redhat or ssun.