We constrain the total mass distribution in the cluster A3571, combining sp
atially resolved ASCA temperature data with ROSAT imaging data with the ass
umption that the cluster is in hydrostatic equilibrium. The total mass with
in r(500) (1.7 h(50)(-1) Mpc) is M-500 = 7.8(-2.2)(+1.4) x 10(14) h(50)(-1)
M-circle dot at 90% confidence, 1.1 times smaller than the isothermal esti
mate. The Navarro, Frenk, & White "universal profile" is a good description
of the dark matter density distribution in A3571. The gas density profile
is shallower than the dark matter profile, scaling as r(-2.1) at large radi
i, leading to a monotonically increasing gas mass fraction with radius. Wit
hin r(500) the gas mass fraction reaches a value of f(gas) = 0.19(-0.03)(+0
.06) h(50)(-3/2) (90% confidence errors). Assuming that this value off,,, i
s a lower limit for the universal value of the baryon fraction, we estimate
the 90% confidence upper limit of the cosmological matter density to be Om
ega(m) < 0.4.