  RXTE observed 20 eclipse egresses of the intermediate polar XY Ari in order
to study the size and structure of the X-ray emitting accretion regions. The
spin-phase averaged egress lasts 26 s, implying a white dwarf radius of 4.3-7.0
10^8 cm. The individual egresses occur later in orbital phase with later spin
phase, as expected if the white dwarf spins in the same sense as the orbital
motion. The eclipse times trace out the motion of the upper pole across the
white dwarf face; then, when the upper pole disappears over the white dwarf
limb and the lower pole appears, they trace the motion of the lower pole across
the face.
  Aligning all the egresses shows that the majority of the X-ray flux emerges
in <2 s, implying accretion regions with area, f, < 0.002 as a fraction of the
white dwarf surface. Using only the spin-phase to align the egresses, however,
gives a longer (~5 s) time for the emergence of the majority of the flux,
implying that the accretion regions wander over an area of f < 0.01. There is
also evidence that a minority of the flux emerges from a much larger area, or
that we see accretion regions at both poles simultaneously at some spin phases.
