J. Kissel, J. Warner

Now that Jim has discovered and fixed my blunder at ETMY recovering the missing factor of ~10 (see 14066), all STSs on site* are functional, well-calibrated, and stored correctly in the frames. Indeed, with the knowledge of the sensor noise (from T0900450) and the plethora of sensitive instruments at End X telling us ground rotation (see LHO aLOG 14047), I think we understand the signals over the entire frequency band where we intend to use them (~10 [mHz] - 10 [Hz]). Well, at least at the X-end.

*used for ISI sensor correction. The vault STS2 which is still out for repair (c.f. )

Several interesting points along the way:
(1) ETMX T240 X and ETMX BRS RY are coherent between 20-80 [mHz], as expected. ETMX T240 Y and Z are *not* coherent, also as expected. This implies that we've well-aligned the X axis of the T240 with the sensitive axis of BRS. Good.
(2) Comparing the coherence between EX RY ground motion with the corner and EY stations' translation DOFS show no coherence. It's not totally crazy to interpret this as meaning the source of ground *tilt* is entirely local to each building. The only way to tell for sure, of course, is to build more BRSs (*hint*hint*).
(3) Each station also varies in the Z DOF, therefore obviously not tilt. Another potential source of noise that might explain this at these low-frequencies is the aging STS2s. Remember EX has a brand new T240, and the remaining GND seismometers are > 10 yr old STS2s. Of course, this could also be thermal drifts, as none of the translational ground motion sensors are as thermally well-isolated as the BRS (HAM2 and HAM5 aren't even a T240 Igloo).
(4) Jim has warned me that, in the corner station, each front-end model reads out HAM2 STSA, Beer-Garden STSB, and HAM5 STSC differently. Further, comparing coherence between each of the corner station STSs, it looks like each could use an alignment tweak-up.