  Pulsars are the most accurate naturally occurring clocks, and data about them
can be used to set bounds on neutron-sector Lorentz violations. If SO(3)
rotation symmetry is completely broken for neutrons, then pulsars' rotation
speeds will vary periodically. Pulsar timing data limits the relevant
Lorentz-violating coefficients to be smaller than 1.7 x 10^(-8) at at least 90%
confidence.
