This is to get a good reference for the corner station alignment.
Prcedure:
Align TMSX, then ITMX, then ETMX, using arm baffle PDs.
Then steer PR3 to get the green transmission in ISCT1.
Then align IR light using PR2 and IM4/IM3 to the arm.
Results:
Green beam locked to the arm, and the green beam was steered to the right location in ISCT1 using PR3.
Good alignment slider values are:
| PIT | YAW | |
| TMSX | -24.25 | -315.55 |
| ETMX | 289.9 | 65.4 |
| ITMX | 90.9 | -7.7 |
| PR3 | -245.0 | -178.9 |
| PR2 | 682.6 | 615.0 |
| IM4 | 21400 | -8500 |
PR3 slider offset used to be (P,Y)=(-279, -80) until this morning, now it's (-245, -178.9), the difference is (34, -98.9) urad.
Due to ITMX motion, the ITMX number might be off by a few urad, and the errors in PR3, PR2 and IM4 should follow ITMX via some ABCD matrix.
The alignment based on the baffle PDs are:
ITMX was moving slowly but by a large amount due to the fact that the ITMX ISI was damping only, and that made it difficult to set the ITMX and ETMX angle correctly using baffle PD method.
Later ETMX and ITMX were aligned to TMSX such that the green light is locked to the cavity.
The green transmission was hitting the swiss cheese baffle, and we used PR3 to clear the baffle hole and put the beam at about the right location on ISCT1.
Without doing anything the green beam is hitting SR3 and maybe SR2 on the video.