  We present the first rest-frame ~4 micron detection of a Lyman break galaxy.
The data were obtained using the 16 micron imaging capability of the Spitzer
Infrared Spectrograph. The target object, J134026.44+634433.2, is an extremely
luminous Lyman break galaxy at z=2.79 first identified in Sloan Digital Sky
Survey spectra (Bentz, Osmer, & Weinberg 2004). The source is strongly detected
with a flux of 0.94 +/- 0.02 mJy. Combining Spitzer and SDSS photometry with
supporting ground-based J- and K-band data, we show that the spectral energy
distribution is consistent with an actively star-forming galaxy. We also detect
other objects in the Spitzer field of view, including a very red MIR source. We
find no evidence of a strong lens amongst the MIR sources.
