  We present the first 350 micron polarization measurement for the disk of the
T Tauri star (TTS) DG Tau. The data were obtained using the SHARP polarimeter
at the Caltech Submillimeter Observatory. We did not detect polarization but we
provide constraints on the normalized Stokes parameters q and u. We derive
information about the polarization spectrum by comparing our 350 micron result
with an 850 micron polarization detection previously published for this source.
This empirical information concerning the polarization spectrum disagrees with
the predictions of a recent model for TTS disk polarization. We conclude,
however, that adding more mass to the model disk would probably result in model
polarization spectra that agree much better with the 350 and 850 micron
polarimetric observations. We suggest that multiwavelength polarimetry of TTS
disk emission may provide a promising method for probing the opacity of TTS
disks.
