There is a bug in the iraf/daophot ii daofind centering code which results in
incorrect fractional pixel corrections being computed for the detected objects.
This error can most easily be detected by plotting the histogram of the
fractional pixel corrections for an image with a large number of detected
objects. The histogram will be modulated at around the 20% level with "peaks"
around the 0.33 and 0.66 fractional pixel values.

This bug is fixed for the next release of iraf and in the external addon
package digiphotx version of daofind. There is no workaround although it
should be emphasized that this bug does not affect the centers computed by
the psf fitting code in the peak, nstar, and allstar tasks. Users concerned
with precision in the daofind results should upgrade their software, or
recenter the objects with the phot "centroid" (fast) or "gauss" (more precise)
routines.

This bug is also present in the standalone version of daophot ii. I have
reported this problem to Peter Stetson and he has fixed it.  Users concerned
about this bug in the standalone version of daophot ii should obtain a fix
from Peter Stetson.