  Using the constrained-fitting method based on Bayesian priors, we extract the
masses of the two lowest states of octet and decuplet baryons with both
parities. The calculation is done on quenched 16^3x28 lattices of a=0.2 fm
using an improved gauge action and overlap fermions, with the pion mass as low
as 180 MeV. The Roper state N(1440)1/2+ is clearly observed for the first time
as the 1st-excited state of the nucleon from the standard interpolating field.
Together with other baryons, our preliminary results indicate that the
level-ordering of the low-lying baryon states on the lattice is largely
consistent with experiment. The realization is helped by cross-overs between
the excited 1/2+ and 1/2- states in the region of pion mass from 300 to 400
MeV.
