Shortly after the first release of the WMAP data three years ago, I
made already the point that the angular power spectrum of the CMB
fluctuations is at least partly due to a systematic error (see my
webpage http://www.physicsmyths.org.uk/wmap.htm ).
This is in my opinion now confirmed by the latest data release:
the difference between the 3- and 1-year maps shows residuals that have
about the same amplitude as the second peak near 0.3 degree in the
power spectrum. This is evident from Figs.3 and 9 in
http://map.gsfc.nasa.gov/m_mm/pub_pa...p_3yr_temp.pdf
(PDF file, 2.3 MB) which reveals a residual temperature fluctuation for
the difference map of about =B120microK. Considering the circumstance
that the difference map was smoothed with a 1 degree radius (which
should have about halved the amplitude) this corresponds thus to the
amplitude of the second peak (which is 50microK). The latter proves
therefore to be due due to statistical fluctuations both in space and
time which, as shown on my webpage, lead to an angular bias resulting
in a residual signal at about 0.3 deg.

Thomas