  We report the detection of linear polarization from SgrA* at 750, 850, 1350
and 2000 microns which confirms the contribution of synchrotron radiation. From
the lack of polarization at longer wavelengths it appears to arise in the
millimetre/sub-millimetre excess. There are large position angle changes
between the millimetre and sub-millimetre results and these are discussed in
terms of a polarized dust contribution in the sub-millimetre and various
synchrotron models. In the model which best explains the data the synchrotron
radiation from the excess is self-absorbed in the millimetre region and becomes
optically thin in the sub-millimetre. This implies that the excess arises in an
extremely compact source to the order of 2 Schwarzschild radii.
