We present the first detection of GG Tau A at centimeter-wavelengths , made with the Arcminute Microkelvin Imager Large Array ( AMI-LA ) at a frequency of 16 GHz ( \lambda = 1.8 cm ) .
The source is detected at > 6 \sigma _ { rms } with an integrated flux density of S _ { 16 GHz } = 249 \pm 45 \mu Jy .
We use these new centimetre-wave data , in conjunction with additional measurements compiled from the literature , to investigate the long wavelength tail of the dust emission from this unusual proto-planetary system .
We use an MCMC based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission .
We derive a dust mass of M _ { d } \approx 0.1 M _ { \odot } , constrain the dimensions of the emitting region and find that the opacity index at \lambda > 7 mm is less than unity , implying a contribution to the dust population from grains exceeding \approx 4 cm in size .
We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres .
Considering the relatively young age of the GG Tau association in combination with the low derived disk mass , we suggest that this system may provide a useful test case for rapid core accretion planet formation models .