  We present the results of ellipsoidal light curve modeling of the low mass
X-ray binary Cen X-4 in order to constrain the inclination of the system and
mass of the neutron star. Near-IR photometric monitoring was performed in May
2008 over a period of three nights at Magellan using PANIC. We obtain J, H and
K lightcurves of Cen X-4 using differential photometry. An ellipsoidal modeling
code was used to fit the phase folded light curves. The lightcurve fit which
makes the least assumptions about the properties of the binary system yields an
inclination of 34.9 (+4.9, -3.6) degrees, which is consistent with previous
determinations of the system's inclination but with improved statistical
uncertainties. When combined with the mass function and mass ratio, this
inclination yields a neutron star mass of 1.51 (+0.40, -0.55) M_sun. This model
allows accretion disk parameters to be free in the fitting process. Fits that
do not allow for an accretion disk component in the near-IR flux gives a
systematically lower inclination between approximately 33 and 34 degrees,
leading to a higher mass neutron star between approximately 1.7 M_sun and 1.8
M_sun. We discuss the implications of other assumptions made during the
modeling process as well as numerous free parameters and their effects on the
resulting inclination.
