We think that our OMC throughput has degraded since installation, 74022, 73873, 69707.  Dana has checked that the balance of the two OMC DCPDs has not changed since installation, 74683. 

Today the question came up if we know if there has been a gradual degradation of the OMC throughput.  The calibration group tracks optical gain which depends on serveral things including OMC throughput.  This is a trend of kappa C, which is remormalized to 1 when the calibration is reset, shown by the time cursors.  This doesn't offer any conclusive evidence that there has been a gradual degredation of the OMC over O4, there has been a slow 2% degredation of the circulating power which can probably explain the slow decrease in kappa C shown here.