J. Garcia, J. Kissel

Jeff G.'s took a round a M0 transfer functions last Friday night, after the same changes:

- The BSC-ISI is floating!
- After all (er most?) of IAS adjustments have been made
- Stiffening elements have been put on
- Vibration absorbers have been put on
- L1 (UIM) and L2 (PUM) OSEMs have been aligned, and masses have been re-balanced accordingingly

It appears as though the F1 problems we were having, which raised all sorts of flags during the last set of measurments (2011-11-29), have continued to be less of a problem. To recap, the list was:
- The dynamics are different from the model, because the d's between the top stage and the UIM stage (parameters dn and d1) are not dead on. (yellow flag)
     Still true, but still only a yellow flag. It could (and most likely) just be that the model is incorrect d values from the "as built" suspension.
- The large offset in the UIM ballast mass (i.e. having it fully forward (HR side)), is causing that stage's horizontal center of mass to be offset from the center line of the suspension (represented by h1). (yellow flag)
     This cross coupling reduced from 2011-11-19 to 2011-11-29, and now is further reduced in the 2011-12-02 measurements. My guess is that whatever IAS work was done to get th test mass aligned in pitch, as well as what re-balancing had to be done after the L1 and L2 flags were installed helped move the center of mass back (or at least more) in-line with the center line of the suspension.
- The overall magnitude of the Pitch transfer functions are a ~50% lower than the model. (yellow flag) This may just be the accuracy of the measurement calibration factor.
       This also appears to be restored. Perhaps for the same alignment reasons as above
- There is an excessive amount of Longitudinal coupling into Pitch. This has been reduced with Travis flag dis- and re- assembly, but some cross coupling still remains. (red flag)
       Related to the second point, and again has reduced what may be negligible coupling.

HOWEVER, what *has* that has been steadily increasing is the cross-coupling of Longitudinal (the lowest modes) into Yaw. I will elevate this only to a yellow flag, because at that frequency, we only are taking data at a 0.01 Hz resolution, so there's a single data point. The data quality around these points is not awesome, so it could just be measurement noise on this data point. However, after looking at the phase comparison between F2 and F3 for these measurements (Yaw to Yaw drive), the two sensors for the past three measurements are in phase at that frequency, implying common mode motion between the two sensors -- i.e. longitudinal motion.