At the last DetChar meeting we talked about a 107Hz peak in Hrec that has a peculiar modulation patter that resembles Etalon. (Figure 1).

Looking at SSFS spectrograms during the long lock of June 1-2 we can see that the 107Hz peak is not alone. There are peaks at about 30.9 Hz, 46 Hz, 62 Hz (non so clear) 77 Hz, 92 Hz, 107Hz, 215Hz that have a similar modulation; Figure 2. They are spaced in frequency by roughly 15Hz.