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Reports until 23:12, Monday 05 October 2015
H1 AOS (DetChar)
nairwita.mazumder@LIGO.ORG - posted 23:12, Monday 05 October 2015 (22253)
Follow up on H1 Loud glitches
I was following up the LHO loud glitches from 26th September. I had a look at the transmitted power signals as done in alog 20395 for dust glitches. The attached pdf contains the plots of band passed (10Hz-100Hz) DARM, as well as ASC-{X,Y}_TR_{A,B}_NSUM_OUT_DQ and SUS-ETMY_L3_MASTER_OUT_LL_DQ channels for the 8  time instances when ETMY saturation was observed. The ETMY saturation times are given below:

 1127380417.6250 1127380418.6875
 1127384361.3750 1127384361.8125
 1127389556.1250 1127389556.2500
 1127403691.3750 1127403691.5000
 1127409078.3750 1127409078.5625
 1127418386.1875 1127418386.4375
 1127423722.0000 1127423722.1250
 1127424221.7500 1127424222.0000
 1127427748.9375 1127427749.0625

It can be noticed that the glitches also appear in  Y TR signals (e.g., ASC-Y_TR_{A,B}_NSUM_OUT_DQ) with large amplitude except the 4th one. For the 4th glitch, it is not visible in ASC-Y_TR_{A,B}. In this particular case, , it is visible in X QPDs  but much smaller than the other ones in Y. Also it doesn't look like that it is much above the noise in the QPD, and even the glitch shape in DARM seems different. In most of these cases DARM is going down and  ASC-Y_TR_{A,B}_NSUM is going up initially. So it is interesting that in spite of ETMY saturation, the glitch shape is completely different as well as nothing can be found in Y QPDs. 


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