  We present results of the point spread function (PSF) calibration of the hard
X-ray optics of the Nuclear Spectroscopic Telescope Array (NuSTAR). Immediately
post-launch, NuSTAR has observed bright point sources such as Cyg X-1, Vela
X-1, and Her X-1 for the PSF calibration. We use the point source observations
taken at several off-axis angles together with a ray-trace model to
characterize the in-orbit angular response, and find that the ray-trace model
alone does not fit the observed event distributions and applying empirical
corrections to the ray-trace model improves the fit significantly. We describe
the corrections applied to the ray-trace model and show that the uncertainties
in the enclosed energy fraction (EEF) of the new PSF model is < 3% for
extraction apertures of R > 60" with no significant energy dependence. We also
show that the PSF of the NuSTAR optics has been stable over a period of ~300
days during its in-orbit operation.
