**Peter E. Freeman, Christopher R. Genovese, Christopher J. Miller,
Robert C. Nichol, and Larry Wasserman**

We analyze first-year data of *WMAP*
to determine the significance of asymmetry in summed power between
arbitrarily defined opposite hemispheres.
We perform this analysis on maps that we create ourselves from
the time-ordered data, using software developed
independently of the *WMAP* team.
We find that over the multipole range
= [2,64], the significance of asymmetry is 10, a
value insensitive to both frequency and power spectrum.
We determine the smallest multipole ranges exhibiting
significant asymmetry, and find twelve, including = [2,3] and [6,7],
for which the significance 0.
Examination of the twelve ranges indicates both an improbable
association between the direction of maximum significance and the ecliptic
plane (significance 0.01), and that contours of least
significance follow great circles inclined relative to the ecliptic
at the largest scales. The great circle for = [2,3] passes over
previously
reported preferred axes and is insensitive to frequency,
while the great circle for = [6,7] is aligned
with the ecliptic poles.
We examine how changing map-making parameters,
e.g., foreground masking, affects asymmetry.
Only one change appreciably reduces asymmetry:
asymmetry at large scales ( 7) is rendered insignificant
if the magnitude of the *WMAP* dipole vector
(368.11 km s) is increased
by 1-3 ( 2-6 km s).
While confirmation of this result requires the recalibration of the
time-ordered data, such a systematic change would be
consistent with observations of frequency-independent asymmetry.
We conclude that the use of an incorrect dipole vector, in
combination with
a systematic or foreground process associated with the ecliptic,
may help to explain the observed power asymmetry.

Heidi Sestrich 2005-10-25 Here is the full PDF text for this technical report. It is 4766908 bytes long.