  We study QCD with (2+1)-HISQ fermions at nonzero temperature and nonzero
imaginary baryon chemical potential. Monte Carlo simulations are performed
using the MILC code along the line of constant physics with a light to strange
mass ratio of $m_l/m_s=1/20$ on lattices up to $48^3 \times 12$ to check for
finite cutoff effects. We determine the curvature of the pseudocritical line
extrapolated to the continuum limit.
