Arnaud, Sheila

We want to try the ETM drive diaonalization.  One reason is that we can see that our longitudnal feedback to the top mass is causing pitch motion of the optic, and we will need the full drive diagonalization when we get the Y arm anyway, so we might as well do it now.  

We had some disscussion about how to balance the coils when there are only 3 osems, in the end we decided to just do length 2 yaw, and then move on to measureing transfer functions.  Tonight Arnaud and I had a first attempt at doing the length 2 yaw measurement, we just applied DC length offsets and used the OpLevs.  This may need to be corrected if the OpLev calibration is revisited tomorow....

When we started there was a -0.004 in the length 2 yaw drivealign matrix, we could not tell from a search through the alog and talking to various people in the control room where this number came from, possibly it was copied over from ETMY.  We have now replaced this with -0.0024.  

Attached is a plot of our measurements and the script we used.