2000ApJ...531..447B

We consider the effect of rapid rotation on the light curves of neutron stars with hot polar caps. For P~3 ms spin periods, the pulse fractions can be as much as an order of magnitude larger than with simple, slowly rotating (Schwarzschild) estimates. Doppler boosting, in particular, leads to characteristic distortion and ``soft lags'' in the pulse profiles, which are easily measurable in light curves with moderate energy resolution. With ∼10⁵ photons it should also be possible to isolate the more subtle distortions of light travel time variations and frame dragging. Detailed analysis of high-quality millisecond pulsar data from upcoming X-ray missions must include these effects.