I measured magnetic coupling at ETMY. The figure shows one of the injections as well as the predicted noise floor from the ambient background of about 10 pT/sqrt(Hz) (transients will likely be greater). The plot also shows the upper limit to suspension coupling that Anamaria and I made at LLO in Nov. 2013 (upper limit because the dominant coupling was to cables not the suspension), and the prediction from my measurements of the moments of individual test mass suspension parts. The value here may also be an upper limit to suspension coupling, if coupling is dominated by cable coupling, but I took the measurement at an end station to reduce this possibility. Also, the behavior is consistent with the 1/f^5 behavior above 20 Hz that I would expect for coupling to the PUM magnets and the coupling factor is close to what was predicted for the PUM magnets.
