Below is the summary of the DQ shift for the week of 21-27 August 2023

• Average range during observing was 140-152 Mpc. The duty cycle each day was M 95.8%, Tu 69.9%, W 75.7%, Th 100%, F 92.9%, Sa 71.4%, Su 86.0% for an average for the week of 85.5%. The long observing period from 22:55 UTC on 23 Aug to 20:19 UTC on 25 Aug of 45h 24m occurred during a record O4 lock of 60h 29m (see aLog 72446).
• The h(t) spectrogram looks clean although the line from 511 Hz violin mode fundamental (and sometimes higher harmonics) are visible and strong at the start of observing periods arising from an unlocked state. This is also true for the 102 Hz line.
• The squeezer (SQZ) system apparently caused the lock loss at 22:59 UTC on 21 August (see aLog 72363)
• As expected, there was excess ground motion during an unlocked period due human acitivity on Tuesday maintenance day.
• H1:PEM-EX_VMON_ETMX_ESDPOWER48_DQ was the hVeto Round 1 or 2 winner every day as it has been throughout O4. ETMX OPLEV channels (e.g., H1:SUS-ETMX_L3_OPLEV_YAW_OUT_DQ) also appeared frequently. On 22 Aug, the HVeto Round 1, Winner was H1:IMC-WFS_B_Q_YAW_OUT_DQ which seemed somewhat unusual. On 23 Aug, another uncommon winner was H1:PSL-ISS_PDB_REL_OUT_DQ. The rest of the week did not show any of these unusual channels.
• On 25 and 26 Aug, SEI/BLRMoverview data missing after 22:00 UTC. On 27 Aug, it stops (at least so far) at 20:00 UTC. This is probably true also for other SEI pages.
• One or both (all frequencies and up to 500 Hz) of the glitchgram and glitch rate plots did not complete starting on 24 Aug.
• A brief increase in the lowest SNR glitch rate was observed on 24, 25, and 27 Aug but only for the high frequency plot.
• A lock was ended due to the failure of a chiller on 25 August (see aLog 72369)
• LASSO picked out 2 potentially interesting channels that appear to correlate with the range drop : H1:HPI-HAM2_ISO_Y_OUT16 and H1:HPI-ITMY_TWIST_FB_Y_INMON. The first of these had many additional channels correlated with it. Both channels seemed to change with the range drop beginning at about 16:30 UTC on 26 August.
• A peculiar noise feature during Observing at about 14:10 UTC on 22 Aug looks like a possible injection.
• FScan Observing shows the number of lines was highest (higher than on 20 Aug) on 21 Aug but below the threshold and fluctuated at lower values throughout the week. Five combs were visible from 21 Aug through 25 Aug. Six combs were visible on 26 - 27 Aug. (It should be noted that the Interactive Spectrum plots do not load for those with slow internet.)

The complete DQ shift report may be found here.