We performed acoustic injections using a subwoofer. The subwoofer was placed in two different locations in both the NEB and WEB. Amplitude was gradually increased. Chronological description of the events: Firstly, the subwoofer was placed near the door in the WEB, connected to the amplifier and the DAC. Interferometer was locked, calibration lines turned off. 09 Sep 2023 07:51:33 UTC (09 Sep 2023 09:51:33 CEST) Quiet reference started. 1378281638 09 Sep 2023 08:00:20 UTC (09 Sep 2023 10:00:20 CEST) Stopped the reference. 1378281949 09 Sep 2023 08:05:31 UTC (09 Sep 2023 10:05:31 CEST) Injected coloured noise with bandpass filter -3db outside 10Hz and 1190Hz in the WEB with amplitude 10^-5 V. 1378282192 09 Sep 2023 08:09:34 UTC (09 Sep 2023 10:09:34 CEST) Increased amplitude of injection to 10^-4V. 1378282341 09 Sep 2023 08:12:03 UTC (09 Sep 2023 10:12:03 CEST) Increased amplitude of injection to 10^-3V. 1378283193 09 Sep 2023 08:26:15 UTC (09 Sep 2023 10:26:15 CEST) Increased amplitude of injection to 5*10^-3V. Limited oscillations visible on Sa_WE_F0_TY. 1378283995 09 Sep 2023 08:39:37 UTC (09 Sep 2023 10:39:37 CEST) Stopped injection. 1378284202 09 Sep 2023 08:43:04 UTC (09 Sep 2023 10:43:04 CEST) Changed injection to coloured noise with bandpass filter -3db outside 10Hz and 110Hz in the WEB with amplitude 5*10^-3V. 1378284396 09 Sep 2023 08:46:15 UTC (09 Sep 2023 10:46:15 CEST) Airplane flew close to the main building. 1378284608 09 Sep 2023 08:49:50 UTC (09 Sep 2023 10:49:50 CEST) Increased amplitude of injection to 2*10^-2V. Coherence visible on ENV_WEB_MIC vs Hrec_hoft_20000Hz between 10Hz and 10^2Hz. 1378285170 09 Sep 2023 08:59:12 UTC (09 Sep 2023 10:59:12 CEST) Increased amplitude of injection to 5*10^-2V. Increased high-frequency noise and low-frequency oscillations visible on super attenuator (Sa_WE_F0_TY). Broadband noise in interferometer visible. 1378285389 09 Sep 2023 09:02:49 UTC (09 Sep 2023 11:02:49 CEST) Stopped injection. Noise on super attenuator immediately disappeared. All noise effects were reversible. 1378288069 09 Sep 2023 09:47:31 UTC (09 Sep 2023 11:47:31 CEST) Went to WEB, changed the position of the subwoofer within WEB so it was far away from the door. Injected coloured noise with bandpass filter -3db outside 10Hz and 1190Hz in the WEB with amplitude 5*10^-3 V. 1378289132 09 Sep 2023 10:05:14 UTC (09 Sep 2023 12:05:14 CEST) Stopped injection. 1378289207 09 Sep 2023 10:06:29 UTC (09 Sep 2023 12:06:29 CEST) Increased amplitude of injection to 1*10^-2 V. Started injection. 1378289405 09 Sep 2023 10:09:47 UTC (09 Sep 2023 12:09:47 CEST) Stopped injection. 1378292049 09 Sep 2023 10:53:51 UTC (09 Sep 2023 12:53:51 CEST) Brought the amplifier from WEB to NEB. Positioned subwoofer next to SAS door, NW corner Interferometer became unlocked (probably by visitors in the main building). Two short injections with low amplitude to test the 'ramp-up' of the subwoofer. 1378292291 09 Sep 2023 10:57:53 UTC (09 Sep 2023 12:57:53 CEST) Stopped test injections. 13:25 UTC - ITF relocked (around 27 Mpc) around 14:01 UTC : a glitch in Hrec produced bumps around 50 Hz line and harmonics (not us) Quiet reference (calib lines off) 14:03 UTC - 14:08 UTC INjection 10-1190 Hz spectral level 5E-3 V started 14:21:00 UTC stopped 14:26:30 UTC Injection 10-110 Hz spectral level 0.02 V started 14:29:00 UTC stopped 14:35:00 UTC Injection 10-110 spectral level 0.05 V started 14:37:00 UTC stopped 14:42:00 UTC 1378307130 09 Sep 2023 15:05:12 UTC (09 Sep 2023 17:05:12 CEST) Went to NEB, changed the position of the subwoofer within NEB so it was far away from the door. Placed on the side of the rack (other side than on the WEB). Picture of new subwoofer position taken by Olivier. Injected coloured noise with bandpass filter -3db outside 10Hz and 1190Hz in the WEB with amplitude 5*10^-3 V. 1378307432 09 Sep 2023 15:10:14 UTC (09 Sep 2023 17:10:14 CEST) Stopped injection. 1378307514 09 Sep 2023 15:11:36 UTC (09 Sep 2023 17:11:36 CEST) Increased amplitude of injection to 1*10^-2 V. Started injection. 1378307827 09 Sep 2023 15:16:49 UTC (09 Sep 2023 17:16:49 CEST) Stopped injection. No significant excess of hrec and no coherence measured.