We present results from Planetary Nebula Spectrograph ( PN.S ) observations of the elliptical galaxy NGC 3379 and a description of the data reduction pipeline .
We detected 214 planetary nebulae of which 191 are ascribed to NGC 3379 , and 23 to the companion galaxy NGC 3384 .
Comparison with data from the literature show that the PN.S velocities have an internal error of \lesssim 20 km s ^ { -1 } and a possible offset of similar magnitude .
We present the results of kinematic modelling and show that the PN kinematics are consistent with absorption-line data in the region where they overlap .
The resulting combined kinematic data set , running from the center of NGC 3379 out to more than seven effective radii ( R _ { eff } ) , reveals a mean rotation velocity that is small compared to the random velocities , and a dispersion profile that declines rapidly with radius .
From a series of Jeans dynamical models we find the B -band mass-to-light ratio inside five R _ { eff } to be 8 to 12 in solar units , and the dark matter fraction inside this radius to be less than 40 % .
We compare these and other results of dynamical analysis with those of dark-matter-dominated merger simulations , finding that significant discrepancies remain , reiterating the question of whether NGC 3379 has the kind of dark matter halo that the current \Lambda CDM paradigm requires .