  Recently, realistic lattice QCD calculations with 2+1 flavors of domain wall
fermions and the Iwasaki gauge action have been performed by the RBC and UKQCD
collaborations. Here, results for the bottomonium spectrum computed on their
gauge configurations of size 24^3x64 with a lattice spacing of approximately
0.11 fm and four different values for the light quark mass are presented.
Improved lattice NRQCD is used to treat the b quarks inside the bottomonium.
The results for the radial and orbital energy splittings are found to be in
good agreement with experimental measurements, indicating that systematic
errors are small. The calculation of the Upsilon(2S)-Upsilon(1S) energy
splitting provides an independent determination of the lattice spacing. For the
most physical ensemble it is found to be a^{-1}=1.740(25)(19) GeV, where the
first error is statistical/fitting and the second error is an estimate of the
systematic errors due to the lattice NRQCD action.
