We noticed sharp peaks on the ASDs measured with the GS13s of HAM3-ISI, since December 11th. The frequencies these peaks were observed were 3.5Hz, and 11Hz (see atachement).

Frequencies, and timing, correspond to Robert's injections for BSC1 magneting coupling tests. One of the coils used for this tests sits right next to HAM3 chamber. It is probably the one that causes the most coupling.

Robert's injections are 5 orders of magnitude above regular ambient magnetic field. The magnetic pickup seen on the GS13s of HAM3-ISI is no more that 2.5 orders of magnitude above seismic level. We are thus fairly confident that GS13s will not be impacted by the usual ambient magnetic field.