the particle background level due to spectral variation is $\sim 24\%$ for the pn and $\sim 10\%$ for the MOS. The double-subtraction method used compensates almost exactly for any discrepancy between the “true” particle background level in a particular profile bin and the estimated level based on the FWC files due to this systematic uncertainty, because the “local” background level we determine will include any deviation in the particle background not accounted for by the scaling FWC component; however, because the vignetting correction in the local background differs slightly from that in the profile bins (by up to $20\%$) a small systematic effect can be introduced. This effect is negligible in most profile bins (including the outermost few bins with the lowest surface brightness where the relative vignetting term is small), and always $<5\%$ (pn) or $<1\%$ (MOS). We therefore conclude that the reported statistical uncertainties on the surface brightness profile accurately reflect the true uncertainty.

Pressure {#pressure-results}
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The dynamics of 3C452 are determined by the relationship between the internal (lobe) and external (thermal) pressure as a function of position in the group.

To calculate the internal pressure we used [synch]{} [@hapr98]. [synch]{} models inverse-Compton scattering of the CMB 