aLIGO LHO Logbook

LHO General

patrick.thomas@LIGO.ORG - posted 20:01, Saturday 22 July 2017 - last comment - 22:01, Saturday 22 July 2017(37707)

Ops Eve Mid Shift Summary

Lost lock at 02:32 UTC. No immediately apparent cause. Relocking. Currently at REDUCE_RF45_MODULATION_DEPTH.

Comments related to this report

patrick.thomas@LIGO.ORG - 20:11, Saturday 22 July 2017 (37708)

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Still at REDUCE_RF45_MODULATION_DEPTH. ISC_LOCK user message says 'waiting for soft loops to converge'. Something does not seem right. The ASC control signals for both pitch and yaw are railing top and bottom on the strip tool and the AS AIR beam spot is jittering. DARM is looking worse and worse.

...Starting to get constant OMC DCPD saturations. Looks like the violins are ringing up. Intentionally killing the lock.

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patrick.thomas@LIGO.ORG - 22:01, Saturday 22 July 2017 (37709)

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Sitting at ROLL_MODE_DAMPING waiting for violin modes to damp. Seems that ITMY mode 5 and ETMX mode 4 are the highest and taking the longest to ring down.