Gas mass $(5.5 \pm 0.6) \times 10^{14} (H_0/50)^{-5/2} M_{\odot}$ within $5(H_0/50)^{-1}$ Mpc, where $H_0$ is the Hubble parameter in km/s per Mpc - Hughes (1989).

Or $(5.1 \pm 1.5) \times 10^{14} (H_0/50)^{-5/2} M_{\odot}$ within $5(H_0/50)^{-1}$ Mpc - Briel et al. (1992).