We present preliminary results from a deep observation lasting almost 200 ks , of the centre of the Perseus cluster of galaxies around NGC 1275 .
The X-ray surface brightness of the intracluster gas beyond the inner 20 kpc , which contains the inner radio bubbles , is very smooth apart from some low amplitude quasi-periodic ripples .
A clear density jump at a radius of 24 kpc to the NE , about 10 kpc out from the bubble rim , appears to be due to a weak shock driven by the northern radio bubble .
A similar front may exist round both inner bubbles but is masked elsewhere by rim emission from bright cooler gas .
The continuous blowing of bubbles by the central radio source , leading to the propagation of weak shocks and viscously-dissipating sound waves seen as the observed fronts and ripples , gives a rate of working which balances the radiative cooling within the inner 50 kpc of the cluster core .