Dr. Dripta , and I went to End X to do an End Station measurement.
We followed a modified version of the T1500062 procedure, that had extra pages availible for taking a a few more optical efficiany measurements.

Beam Spot before we started looked good.

We did our normal procedure and then did a little jumping around to minimize the number of times WSH(PS4) was passed under the beam tube.
The Extra long Optical Effiency measurements were the same configuration that we normally have for our Optical Efficiency measurements, but the durration was 900 secods. That analysis is still pending.

Beam spots after we were finished also looked good.

Analysis:

Martel tests looked a little lower than normal at 4 V.
WS @ TX png
WS @ RX png
WS @ RX Both Beams

WS "PS4" --date "2024-09-23"
Reading in config file from python file in scripts
../../../Common/O4PSparams.yaml
PS4 rho, kappa, u_rel on 2024-09-23 corrected to ES temperature 300.6 K :
-4.70978667092155 -0.0002694340454223 4.121866697713714e-05
Copying the scripts into tD directory...
Connected to nds.ligo-wa.caltech.edu
martel run
reading data at start_time:  1411229815
reading data at start_time:  1411230420
reading data at start_time:  1411230760
reading data at start_time:  1411234174
reading data at start_time:  1411234615
reading data at start_time:  1411234975
reading data at start_time:  1411237284
reading data at start_time:  1411237906
reading data at start_time:  1411238249
Ratios: -0.4623501228701653 -0.46585957548893536
writing nds2 data to files
finishing writing
Background Values:
bg1 =        8.765046; Background of TX when WS is at TX
bg2 =        5.318545; Background of WS when WS is at TX
bg3 =        8.952192; Background of TX when WS is at RX
bg4 =        5.319887; Background of WS when WS is at RX
bg5 =        8.841055; Background of TX
bg6 =        0.521412; Background of RX

The uncertainty reported below are Relative Standard Deviation in percent 

Intermediate Ratios
RatioWS_TX_it      = -0.462350;
RatioWS_TX_ot      = -0.465860;
RatioWS_TX_ir      = -0.456872;
RatioWS_TX_or      = -0.460592;
RatioWS_TX_it_unc  = 0.091320;
RatioWS_TX_ot_unc  = 0.083249;
RatioWS_TX_ir_unc  = 0.090438;
RatioWS_TX_or_unc  = 0.091453;
Optical Efficiency
OE_Inner_beam                      = 0.988290;
OE_Outer_beam                      = 0.988868;
Weighted_Optical_Efficiency        = 0.988579;

OE_Inner_beam_unc                  = 0.059378;
OE_Outer_beam_unc                  = 0.058135;
Weighted_Optical_Efficiency_unc    = 0.083099;

Martel Voltage fit:
Gradient      = 1636.760986;
Intercept     = 0.654137;

 Power Imbalance = 0.992467;

Endstation Power sensors to WS ratios::
Ratio_WS_TX                        = -1.077343;
Ratio_WS_RX                        = -1.390443;

Ratio_WS_TX_unc                    = 0.053215;
Ratio_WS_RX_unc                    = 0.043612;

=============================================================
============= Values for Force Coefficients =================
=============================================================

Key Pcal Values :
GS           =      -5.135100; Gold Standard Value in (V/W)             
WS           =      -4.709787; Working Standard Value             

costheta     =      0.988362; Angle of incidence
c            =      299792458.000000; Speed of Light
             
End Station Values : 
TXWS         =        -1.077343; Tx to WS Rel responsivity (V/V)
sigma_TXWS   =        0.000573; Uncertainity of Tx to WS Rel responsivity (V/V)
RXWS         =        -1.390443; Rx to WS Rel responsivity (V/V)
sigma_RXWS   =        0.000606; Uncertainity of Rx to WS Rel responsivity (V/V)

e            =        0.988579; Optical Efficiency
sigma_e      =        0.000822; Uncertainity in Optical Efficiency

Martel Voltage fit : 
Martel_gradient         =        1636.760986; Martel to output channel (C/V)
Martel_intercept   =        0.654137; Intercept of fit of     Martel to output (C/V)

Power Loss Apportion : 
beta          =        0.998895; Ratio between input and output (Beta)  
E_T          =        0.993723; TX Optical efficiency 
sigma_E_T          =        0.000413; Uncertainity in TX Optical efficiency 
E_R          =        0.994823; RX Optical Efficiency 
sigma_E_R          =        0.000413; Uncertainity in RX Optical efficiency 

Force Coefficients : 
FC_TxPD          =        7.889514e-13; TxPD Force Coefficient 
FC_RxPD          =        6.183572e-13; RxPD Force Coefficient 
sigma_FC_TxPD          =        5.348574e-16; TxPD Force Coefficient 
sigma_FC_RxPD          =        3.744092e-16; RxPD Force Coefficient 
data written to ../../measurements/LHO_EndX/tD20240924/

Things to note about this measurement.
A: Long measurement, Analysis pending.
B: There was a maintenance day item for FAC - [CR] Raise the chilled water set point. (Tyler, E. Otterman) WP12102 which could optics to "move more than usual" I dont think this had much impact on us.

This adventure was brought to you By Dr. Dripta & Tony.