Reports until 11:53, Monday 16 January 2017
H1 SUS
jenne.driggers@LIGO.ORG - posted 11:53, Monday 16 January 2017 (33340)
TMS / ITM ditheralign script left ITMY not misaligning enough

Patrick almost has us initially aligned and ready to start the acquisition sequence, so we have not yet started to look into the problem at LownoiseASC.  But, we have found and resolved the a problem that operators have been having with initial alignment over the last day. 

The TMS and ITM ditherAlign script had been run yesterday for the Yarm, to help find the green beam.  I don't know at this time why that was necessary, but it left some incorrect offsets in ITMY that made initial alignment harder. 

We use the same M0_TEST offset for the dither align script as we do for the MISALIGN suspension guardian state.  The dither align script needs smaller values in there than the usual misaligned location, so it writes the values it needs.  However, it wasn't putting the usual offset values back after the script finished, so when trying to lock the Xarm-only in IR during initial alignment, ITMY was only partially misaligned and there were fringes at the AS port causing confusion and poor error signals. 

I have reverted the M0_TEST offsets to the values in SDF, and have modified the ditherAlign script such that it reads the original offset value, and puts it back upon completion of the script so that this doesn't happen again.