Conclusion: T2000599-v6 (r13010) of bbssopt.m matches LHO parameters, T2000599-v5 (r12764) matches LLO's current configuration, but the difference in the models is negligible

The M3 mass listed in the bbssopt.m parameter set has been changed from 20.99kg to 20.909kg to match the mass of LHO's BBSS M3 optic.

This mass is given by the mass of the optic itself (20889g) + the mass of the primary prisms (7.56g and 7.46g) + the mass of the secondary prisms (5.57g together). This gives us 20.909kg. The change in the model from this is very minimal - the highest Pitch peak shifts down by a few hundreds of uHz, from 1.1656Hz to 1.1615Hz.

LLO's BBS02 is 21.065kg, and comparing this to the previous dummy's mass, the peaks are still in the same place, so the previous version of the model, v5 (r12764) matches with their current configuration, but since the shift is so minimal, using the same model that LHO is using would be fine.

I've updated T2000599 to -v6, and committed /ligo/svncommon/SusSVN/sus/trunk/Common/MatlabTools/TripleModel_Production/bbssopt.m to r13010.

The comparison for all DOFs for all three mass changes can be found at /ligo/svncommon/SusSVN/sus/trunk/BBSS/Common/Results/comparetripleparams/2026-05-20_M3_DummyvsLHOvsLLO/triplemodelcomp_2026-05-20_M3_DummyvsLHOvsLLO_M1toM1.pdf and committed to svn as r13011.