  We monitor the star HD 149026 and its Saturn-mass planet at 8.0 micron over
slightly more than half an orbit using the Infrared Array Camera (IRAC) on the
Spitzer Space Telescope. We find an increase of 0.0227% +/- 0.0066% (3.4 sigma
significance) in the combined planet-star flux during this interval. The
minimum flux from the planet is 45% +/- 19% of the maximum planet flux,
corresponding to a difference in brightness temperature of 480 +/- 140 K
between the two hemispheres. We derive a new secondary eclipse depth of 0.0411%
+/- 0.0076% in this band, corresponding to a dayside brightness temperature of
1440 +/- 150 K. Our new secondary eclipse depth is half that of a previous
measurement (3.0 sigma difference) in this same bandpass by Harrington et al.
(2007). We re-fit the Harrington et al. (2007) data and obtain a comparably
good fit with a smaller eclipse depth that is consistent with our new value. In
contrast to earlier claims, our new eclipse depth suggests that this planet's
dayside emission spectrum is relatively cool, with an 8 micron brightness
temperature that is less than the maximum planet-wide equilibrium temperature.
We measure the interval between the transit and secondary eclipse and find that
that the secondary eclipse occurs 20.9 +7.2 / -6.5 minutes earlier (2.9 sigma)
than predicted for a circular orbit, a marginally significant result. This
corresponds to e*cos(omega) = -0.0079 +0.0027 / -0.0025 where e is the planet's
orbital eccentricity and omega is the argument of pericenter.
