DARM calibration was updated by minimum subset of measurements as the quick check.
Optical gain, Hc, and actuator efficiency of TM, Htm, were updated as follows.
- Hc = (2.133 +/- 0.015)e12 [+10.0%] (fixed fcc=18Hz model)
- Htm = (3.892 +/- 0.020)e-14@10Hz [+1.0%]
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As the quick calibration, 3 TFs (DARM_OLTF, ETMX_TM to DARM_ERR, and X-Pcal to DARM_ERR) were measured. In current stability, it's difficult to measure 3 TFs in same IFO lock. So they were measured in 2 different locks. I haven't checked that this instability comes from IFO itself or large injection (but it's no problem before Aug.) induces instability now. Anyway, it seems difficult to move Weekly or full calibration now because they require to measure 6 TFs and 11 TFs with PRFPMI_DC lock.
Measured 3 TFs were shown in Fig.1-3. Difference from the reference TFs (blue curve) is small but these references were measured in June. Checking last calibration measurements in August (klog#34777), then there was ~1dB difference in OLTF. In addition as important information about these measurements for analyses, the lowest frequency in TF from X-Pcal to DARM_ERR was contaminated by lockloss and the lowest frequency was removed from my analysis. Actuator efficiency of TM is estimated as the ratio by Pcal as shown in Fig.4-5. Because these two TFs were measured in the different locks, it may be affected by the change in open loop gain in two locks. 1-2dB deviation from frequency average around 50-200Hz seems to come from this effect. In addition, update of VIS filter module (179Hz notch) in klog#35480 was simulated at CAL-CS_DARM_FE_ETMX_TM_LOCK_L_FM2.
Optical gain was estimated from estimated actuator efficiency above and OLTF with fixed fcc model as shown in Fig.6-7. Optical gain, here, contains also a change in INMTRX reported in klog#35380. On the other hand, a gain change by filter modules in klog#35470 is not contained and it's compensated at CAL-CS_DARM_ERR_FM9 (see also Fig.8).
Finally, inverse optical gain at CAL-CS_DARM_ERR_FM1 and actuator efficiency of TM at CAL-CS_DARM_ANALOG_ETMX_TM_FM1 were also updated and loaded by CALCS model around 17:30. All filter updates were shown in Fig.9.
The estimated values are listed below and confirm that there is no significant inconsistency with the values reported above.
- Hc = (2.052 +/- 0.002)e12 [-3.9% from the above value](fixed fcc=18Hz model)
- Htm = (3.975 +/- 0.004)e-14@10Hz [+2.0% from the above value]
The fitting results and residuals are shown in Fig. 1.
--- Notes on the small differences
Optical gain: There is a −3.9% difference. This arises because my computed value is optimized for the LL pipeline, which matches the trend seen in past measurements. So this is not an issue. For example, the previous case showed a −2.4% difference; however, fcc was not fixed at 18 Hz in that case.
Actuator efficiency of TM: The +2% difference observed here is probably explained by my fitting not including the IM stage, which would bias the inferred TM efficiency upward. When the IM stage was included in previous analyses, our values were in close agreement (≈0.45% difference in the last measurements).
