  We estimate the amount of the {\it missing baryons} detected by the \Planck\
measurements of the cosmic microwave background in the direction of Central
Galaxies (CGs) identified in the Sloan galaxy survey. The peculiar motion of
the gas inside and around the CGs unveils values of the Thomson optical depth
$\tau_{\rm T}$ in the range $0.2$--$2\times 10^{-4}$, indicating that the
regions probed around CGs contain roughly half of the total amount of baryons
in the Universe at the epoch where the CGs are found. If baryons follow dark
matter, the measured $\tau_{\rm T}$s are compatible with the detection all the
baryons existing inside and around the CGs.
