Attached are plots of PR3 comparing power spectra from L1 PR3 (June 2012), H1 PR3 (Feb 14th 2013 before Betsy changed the brackets), H1 PR3 (Feb 19th 2013 after changing the brackets), and H1 PR3 (Feb 20th 2013 after recentering M2 UL OSEM and moving one of the top EQ stops).

To sum up, some investigation has been done to understand why some peaks from Feb 13th PR3 power spectra has been shifted in frequency  (see the ~3.2 Hz peak on the red curve for M2 Pitch page 18 on allhltss_2013-02-20_Phase2b_PR3_ALL_Spectra_Doff ). After making few changes as described above, the new power spectra taken yesterday (Feb 20th) look consistent.

PR3 is now ready to get installed in the chamber.