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This afternoon we investigated the effect of moving transversally SDB1 and SR on the scattered light observed on SDB1 with the FrontRight and BackRight cameras.

The transversal motion of SDB1 and SR (that is to say motion along the south-north axis) was achieved by changing the set point of the F0 of the concerned suspensions.

The nominal position of SDB1 corresponds to Sa_OB_F0_Z = 0 and SDB1_LC_TY = -3580 urad. The nominal position of SR corresponds to Sa_SR_F0_Z = -50 um. Pictures 1 and 2 shows the images of the cameras in nominal conditions (data in low noise 1, from 14h30 to 14h44 utc).

Below is a list of the tested positions:

Sa_OB_F0_Z = +700 um (bench moved towards south) ; SDB1_LC_TY = -3535 urad and SDB2_LC_TY = +1600 urad (SDB2_LC_TY and SDB1_LC_TY have been adjusted to keep the beam on the B1p_PD2 photodiode). Data in low noise 1 from 14h17 to 14h21 utc - see Images 3 and 4.
Sa_OB_F0_Z = -700 um (bench moved towards north) ; SDB1_LC_TY = -3700 urad and SDB2_LC_TY = -1400 urad (SDB2_LC_TY and SDB1_LC_TY have been adjusted to keep the beam on the B1p_PD2 photodiode). Data in low noise 1 from 15h09 to 15h20 utc - see Images 5 and 6.
Sa_OB_F0_Z = -700 um (bench moved towards north) ; SDB1_LC_TY = -3800 urad and SDB2_LC_TY = -750 urad (SDB2_LC_TY and SDB1_LC_TY have been adjusted to recover the beam on the B1s2 photodiode). Data in low noise 1 from 15h30 to 15h35 utc - see Images 7 and 8.
Sa_SR_F0_Z = -800 um ; Sa_OB_F0_Z = +750 um (bench moved towards south) ; SDB1_LC_TY = -3590 urad and SDB2_LC_TY = +1000 urad (SDB2_LC_TY and SDB1_LC_TY have been adjusted to recover the beam on the B1p_PD2 photodiode). Data in low noise 1 from 16h48 to 16h54 utc - see Images 9 and 10.
Sa_SR_F0_Z = +700 um ; Sa_OB_F0_Z = -750 um (bench moved towards north) ; SDB1_LC_TY = -3590 urad and SDB2_LC_TY = -1000 urad (SDB2_LC_TY and SDB1_LC_TY have been adjusted to recover the beam on the B1p_PD2 photodiode). Data in low noise 1 from 17h06 to 17h13 utc - see Images 11 and 12.