Sheila and Jenne informed me that the TSC ITMY CO2 guardian suddenly had changed its state this evening, kicking us out of the observing mode

I trended some relevant data and checked the guardian logs. It seems that since the upgrade of the guardian machine this morning (32072), the TCS CO2 guardians for both X and Y arms unlocked multiple times for some reason. The first attachment is the trend of some relevant channels for this past 12 hours. As shown in the upper panels, the guardians changed their states multiple times in the past hours due to the lasers unlocked. Reading the guardian logs (which are attached) and codes, these events were indentified to be due to the PZT output signals exceeding some thresholds that are set in the guardian codes. This had not happened in the past four or five days until this morning. The number of incidents seems to decrease as a function of time. I am hoping that the CO2 lasers will eventually settle to some kind of stable point in which the guardians don't need to change the state any more.

For operators,

If this happens again (which should be obvious as it flips the intent bit back to commissioning), please follow the following procedure.

• Determine whether if the TCS ITMX(Y) CO2 guardian changed the state.
  • The easiest would be to look at the log of the IFO guardian (accessible at the very top of GUARD_OVERVIWE.adl)
  • If it's not TCS. The below doesn't apply.
• Record the time of the incident so that the time stamp can be noted in the operator's summary log.
• Wait for the TCS guardian to come back to the nominal state.
• Once the TCS guardian is back to nominal, hit the intent bit and go back to observing.