J. Kissel, R. Mittleman, R. McCarthy

Looking for functional STS-2s to use for BSC-ISI sensor correction at ETMX, one suggestion that came up was the Vault STS-2. However, Rich immediately reminded us that it's over 10 years old and hasn't received any TLC in a while, so it's most likely functioning poorly at low-frequency and will need to be shipped back to Quanterra for maintenance. To confirm, I've measured its low-frequency coherence with the functional corner station STS-2s. Ideally, we'd go grab the VAULT STS2, and huddle test it against one of the LVEA STSs, but ... it's cold, and for the frequencies we're concerned about it shouldn't matter.

In summary -- yes: the VAULT STS-2 is poorly coherent with any of the corner. If functional, we'd expect to see coherence down to 50-60 mHz in the Z directions. Richard suggest we'll grab in the Spring.

Details:
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Serial Number Layout:
HAM2 -- SN 89922
HAM5 -- SN 100145F
ITMY -- SN 89941
VAULT -- (Known, but not yet by me)
(ETMY -- SN 89938)

Calibration Details:
HAM2, HAM5, and ITMY -- 1e-9 [(m/s) / (nm/s)]. These aLIGO GND STS2s, with channels H1:ISI-GND_STS_${CHAMBER}_${DOF}_DQ, are already calibrated in the front end to (nm/s), so all I have to do was convert to (m/s).
VAULT -- 3.052e-7 [(m/s) / ct]. Although pem.ligo.org suggests that the calibration should be 0.0076e-6 [(m/s) / ct], it did not match any of the corner station STS-2s at the microseism, where the motion should be identical. So, I just scaled the VAULT to match. Further, the channels are different from pem.ligo.org, they're now H1:PEM-VAULT_SEIS_1030X195Y_STS2_${DOF}_DQ