Cool Stars 14 - Submitted Abstract # 297 This version created on 05 October 2006 The Spitzer MIPS 24 micron Photometric Light Curve of the Eclipsing M-Dwarf Binary GU Boo Kaspar von Braun, Michelson Science Center / Caltech Gerard T. van Belle, Michelson Science Center / Caltech David Ciardi, Michelson Science Center / Caltech Stefanie Wachter, Spitzer Science Center / Caltech Donald Hoard, Spitzer Science Center / Caltech We present a carefully controlled set of Spitzer 24 micron MIPS time series observations of the low mass eclipsing binary star GU Boötes. These observations serve to characterize the MIPS-24 observing techniques of the spacecraft, precisely establishing the photometric repeatability of this instrument at the tens of microJy level. The data aim to substantiate the previously announced GO-1 and upcoming GO-2 observations of extrasolar planet transits at similar levels of precision. An additional science return is the first-ever long wavelength characterization of such a low-mass object's light curve, allowing for improved characterization of the components' linear radii, in addition to other aspects of their surface morphology. In this presentation, we show GU Boo's 24 micron light curve and give our estimates concerning astrophysical parameters of the binary system. ----------------------------------