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Reports until 13:24, Friday 28 October 2022
H1 AOS (SQZ, SUS, SYS)
jason.oberling@LIGO.ORG - posted 13:24, Friday 28 October 2022 (65509)
FC2 Initial Alignment Complete

Rahul has informed that final FC2 TFs are clear of rubbing, so the initial alignment of the optic is now complete.  The final alignment numbers are listed in the table below (corrected for FC2 yaw and placed in the LHO global coordinate frame).

One note regarding FC2 pitch.  As everything at the FCES is leveled to local gravity at the FCES (the HAM8 chamber, the HAM8 ISI, the FC2 SUS, and the IAS alignment equipment), I have to correct for the local gravity difference between the FCES and the LVEA to properly align FC2.  In this case the correction is small at ~35µrad (or 0.002°), but it does change the target pitch for FC2.  In the global IFO coordinate frame, the target pitch for FC2 is 0.149°, pitched down; this becomes 0.151°, still pitched down, once this local gravity correction has been made.  The local gravity correction is found in the file "Find LIGO Global axis pitch wrt local horizontal (level) at any position" in version 5 of E1200080.

  Position (mm) Pointing (µrad)
X Y Z Pitch Yaw
Target 5022.0 279196.0 676.5 2635 down 3578 CW
Actual 5022.3 279193.3 676.5 2455 down 3618 CW
Error +0.3 -2.7 0.0 180 up 40 CW
Tolerance +/-1.0 +/-3.0 +/-1.0 +/-150 +/-150

While the pitch error is slightly outside of our chosen tolerance, it's still well within the pitch range of the FC2 HSTS (which if I remember correctly is on the order of several milliradians); as such, we decided to leave it as-is.

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