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Message ID: 1563     Entry time: Fri May 8 04:46:01 2009
Author: rana, yoichi 
Type: Summary 
Category: oplevs 
Subject: BS/PRM/SRM table bad! 
We went to center the oplevs because they were far off and found that (as usual) the numbers changed
a little after we carefully centered the oplevs and came back to the control room.

To see if the table was on something soft, we tried pushing the table: no significant effect with ~10 pounds of static force.

With ~10 pounds of vertical force, however, we saw a large change: ~0.25 Oplev units. This corresponds to
~20-30 microradians of apparent optic pitch.

In the time series below you can see the effects:

2.5 s: lid replaced on table after centering.

2.5 - 11 s: various force tests on table

11 s: pre-bias by aligning beams to +0.25 in pitch and then add lid.


So there's some kind of gooey behavior in the table. It takes ~1 s to
settle after we put the lid on. Putting the laptops on the table also
has a similar effect. Please do not put anything on this table lid.
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