Ivey and Edgard,

We just finshed a fit of the Yaw-to-Yaw transfer functions for the OSEM estimator using the measurements that Oli took for SR3 last Tuesday [see LHO: 85288].

The fits were added to the Sus SVN and live inside '~/SusSVN/sus/trunk/HLTS/Common/FilterDesign/Estimator/fits_H1SR3_2025-06-30.mat' . They are already calibrated to work on the filter banks for the estimator and can be installed using 'make_SR3_yaw_model.m', which lives in the same folder [for reference, see LHO: 84041, where Oli got the fits running for a test].

Attached below are two pictures of the fits we made for the estimator.

The first attachment shows the Suspoint Y to M1 DAMP Y fit. We made sure to fit the asymptotic behavior as well as we could, which ends up being 0.95x10^{-3} um/nm (5% lower than expected from the OSEM calibration). The zpk for this fit is

    'zpk([-0.024+20.407i,-0.024-20.407i,-0.044+11.493i,-0.044-11.493i,0,0],[-0.067+21.278i,-0.067-21.278i,-0.095+14.443i,-0.095-14.443i,-0.07+6.405i,-0.07-6.405i],-0.001)'

The second attachment shows the M1 drive Y to M1 DAMP Y fit. We kept the same poles that we had for the other fit, but manually fit the zeros and gain to make a good match. The zpk for this fit is

'zpk([-0.051+8.326i,-0.051-8.326i,-0.011+19.259i,-0.011-19.259i],[-0.067+21.278i,-0.067-21.278i,-0.095+14.443i,-0.095-14.443i,-0.07+6.405i,-0.07-6.405i],12.096)'

Hopefully Oli and co. will have time to test this soon!