Persuant to WP 6133, II 1150, FRS 4649 JimW & HughR
With the SEI completely deisolated, we lifted the platform with the HEPI payload springs. We addressed the Z and tilt dofs. The vertical drives on the Actuators were reduced substantially (8-6000 cts reduced to ~1200 or less.) Sadly, the horizontal drives increased albeit less than the verticals were reduced: a few hundred cts to 5000, 2000, 1500, & 900 cts. We would have addressed these too but Jim found Spring #4 (SE spring of SW pier) was feeling very galled. Will file an Integration Issue to track this Spring problem. Probably would need to remove the vertical actuator to access the Spring/XBeam Foot connection, but maybe we could get lucky.
The attached trends show the BS HEPI drives (OUTF ij OUTPUT) and the cartesian positions (..LOCATIONMON.) The unisolated positions (when the drives are 0) can be seen changing as we adjust the springs.
The next largest HEPI Drive is horizontal on the ITMY where 4000 to 5000 counts are holding a 300um +X offset remaining from Initial Alignment--II 1151, FRS 4650. After that, the BS Horiz, HAM1 Horiz, HAM2 and ETMX, if we care.
True, as long as HEPI is running fine, no big deal. And, unless we take all DOF errors out, IFO ops will not be possible without the HEPI Isolated. Would be nice to head to a state where, if we were to lose HEPI Pump Stations or a platform for a time, the position was such that IFO operations could continue.