  Images obtained by drift-scanning with a stationary telescope are affected by
the declination-dependent curvature of star trails. The image displacement to
curvature and drift rate variation increases with the angular field of view and
can lead to significant loss of resolution with modern large-format CCD arrays.
We show that these effects can be essentially eliminated by means of an optical
corrector design in which individual lenses are tilted and decentered. A
specific example is presented, of a four-element corrector designed for the
Large-Zenith Telescope. The design reduces curvature errors to less than 0.074
arcsec over a 10 arcmin x 20 arcmin field of view centered at 49 degrees
declination. By changing the positions and tilts of the lenses, the same design
can also be used for any field centers between 0 degrees and 49 degrees.
