Attached are darm spectra, with times choosen to be higher range times for each configuration.  The first comparison shows O4a  with OM2 hot vs cold, once the feedforward was retuned well with OM2 hot there was an improvement at low frequency but the high frequency was slightly worse, so that the BNS range is similar between the two configurations O4a hot vs cold OM2

In the break, improvements in the DARM offloading and other low frqeuency improvements meant that the low frequency noise floor is lower.  O4a vs Ob4 compare.  This also means that we have been more aware of the ASC and LSC coherences changing at low frequency and impacting our range.  The second screenshot shows the O4a times compared to two O4b times, both with OM2 cold but before and after the output arm change on April 22nd. 

Since we saw a change in low frequency sensitivity back in December with hot OM2, it would be interesting to try this test again soon.