Elenna, Camilla, TJ, Matt, Oli

A few hours into a lock stretch we suddenly had a couple of large oscillations come in (ndscope1). They happened at 1437260896 for 2 seconds and at 1437260919 for 2 seconds. There were no saturations and our range did not drop more than 10 Mpc the next minute.

In DARM (ndscope2), the frequency of these oscillations is between 5.7-6 Hz. In the QUAD MASTER_OUT (ndscope3) and ASC (ndscope4, ndscope5) channels, the oscillation frequency is around 2.5 Hz. In the QUAD oplev channels (ndscope6), the oscillation frequency is around 2.5 Hz, and it's seen in all quads except ITMX. There is also a slight delay between when the quads move, with ITMY looking like it moved first.