Before starting to move things around the PSL table, I measured the ALS out of loop noise for reference. The noise spectrum showed excess noise around 30Hz.  The traces in blue were taken before I went in and those in red were taken after my work.

I also looked at the power spectrum of LSC-TRY_OUT to see if the noise is from the IR lock itself and there was nothing suspicious with it. 

Since the green transmission was 50% lower than the usual, I touched the steering mirrors for green at the Y end table to get a better transmission and beat signal. The noise still hasn't disappeared. 

I am not sure if this could be from our neigbors who have been running rock experiments since morning. We should check back to see if this noise disappears once they shut down.

DTT xml files are available in directory /users/manasa/data/150109/