Correcting for r_s(z_drag) in BAO measurements in cosmomc

[Eyal Kazin]

I would like to better understand what has been done regarding the usage of the sound horizon at the end of the drag epoch r_s(z_drag) parameter, so I can best use cosmomc with the BAO measurements.

Section 5.2 the Planck paper XVI reads:
"In CosmoMC we multiply the accurate numerical value of r_s(z_drag) by a constant factor of 1.0275"

I understand where this factor is coming from, but would like to understand if this factor is hard coded in the public code. I looked at the bao.f90 file and did a grep of 1.0275 in the source directory, but did not see anything apparent.

In the cosmomc readme file it says:
"Note the code is not identical, cosmomc computes the drag sound horizon numerically (recalibrated to be consistent in the fiducial model)"

Does this mean that I should multiply the 6DF, SDSS (DR7 and DR9) results with this factor (or something similar) myself in the *_bao.txt files?

(Also, I think that 6DF should be updated to use their Dv/rs result, not their Dv result, as 6DF does not contain rs information)

[Antony Lewis]

The number is the constant rs_rescale = 153.017d0/148.92 in bao.f90.