Naoki called the control room pretty early and suspected that the Locklosses from last night were from some PI ring ups as seen in Ryans alog 79860 .
So I told him I'd check it out and document it.
Last night during the spooky & completely automated OWL shift, when no one was around to see it. There were 5 episodes of lock aquisition and locklosses that strangely all happened around the time when the Lock Clock approached the 2 hour mark.
Turns out, Naoki's gut instinct was right, they were PI ring ups !
Not only was he correct that the Locklosses were caused by PI ring ups but they were Dreaded Double PI Ring up! Some Say that the Double PI ring up is just a myth or an old operator's legend. Its supposedly a rare event when 2 different Parametric Instabilities modes ring up at the same time!
But here is a list of the Dreaded Double PI ring up sitings from just last night!
2024-09-02_05:34:01Z ISC_LOCK NOMINAL_LOW_NOISE -> LOCKLOSS Cause: The Dreaded Double PI 28 And 29!!! The SUS-PI guardian did not change the phase of compute mode 28 at all. Lockloss page
2024-09-02_08:06:14Z ISC_LOCK NOMINAL_LOW_NOISE -> LOCKLOSS Cause: Another Deaded Double PI 28 & 29! Compute mode 28 phase was not moved again this time. Lockloss page
2024-09-02_10:37:06Z ISC_LOCK NOMINAL_LOW_NOISE -> LOCKLOSS Cause: Dreaded Double PI ring up But this time the Phase for 28 changed, But by then it was too late for everyone involved! ( No one was invloved, cause this was completetly automated.)
Lockloss page
3: 2024-09-02_12:38:45Z ISC_LOCK NOMINAL_LOW_NOISE -> LOCKLOSS Ok I'll admit that this one is not a Dreaded Double PI ring up... but it certainly is a PI 24 ring up!
Lockloss page After getting some second Eyes on this i am now Convinced that this is a Wind Gust Lockloss.
Maybe it is just the SUS-PI Guardian is having trouble damping PI28 and instead is trying to damp PI29 but that must be ringing up PI mode 29.
If it happens again, Naoki has asked me to simply take the SUS-PI Guardian to IDLE and take the damping gains for 28 & 29 to 0.
Wish me luck.
