Following up on the earlier post 4327 concerning H2 OAT line studies, I am attaching additional slides containing plots and tables that compare the OAT spectrum from August 28 (focus of last report) with spectra on Sept 7 (generally quieter with fewer combs) and on Sept 13 when the aLIGO PSL was being used for the ALS reference. The spectrum on Sept 13 has a higher noise floor, more lines and stronger lines in many cases. In addition, a number of combs observed on August 28 moved slightly in fundamental frequency by Sept 7 and moved again by Sept 14. See slides for details.