  We present a carefully controlled set of Spitzer 24 \micron MIPS time series
observations of the low mass eclipsing binary star GU Bo\"otis (GU Boo). Our
data cover three secondary eclipses of the system: two consecutive events and
an additional eclipse six weeks later. The study's main purpose is the long
wavelength characterization of GU Boo's light curve, independent of limb
darkening and less sensitive to surface features such as spots. Its analysis
allows for independent verification of the results of optical studies of GU
Boo. Our mid-infrared results show good agreement with previously obtained
system parameters. In addition, the analysis of light curves of other objects
in the field of view serves to characterize the photometric stability and
repeatability of {\it Spitzer's} MIPS-24 at flux densities between
approximately 300--2,000$\mu$Jy. We find that the light curve root mean square
about the median level falls into the 1--4% range for flux densities higher
than 1 mJy.
