tokens: flux from near the heliotail. Figure 3 can be directly compared to Fig. 9 of Funsten et al. (2015) , who analyzed the symmetry of the IBEX ribbon; however, note that Funsten et al. plot the IBEX ribbon flux and location as a function of angle from the ribbon symmetry axis, which lies within 40 of the plane (0 azimuth in our Fig. 3 ). The IBEX ribbon flux appears to maximize close to the symmetry axis for 0.71 and 1.11 keV, relatively close to the plane (within 30), similar to our results at low ENA energies for the case of slow SW, and high ENA energies during fast SW – both in the absence of an asymmetric SW. At higher energies, the IBEX ribbon flux appears bimodal, likely due to the asymmetric SW, which is excluded in our study. Nevertheless, in all cases, our results appear to be symmetric about the plane. This suggests that, besides the possible influence of the latitudinal asymmetry of the SW, the hydrodynamic interaction of the SW with the LISM, centered on the trajectory of the heliosphere through the interstellar gas, is an important ordering process for the ribbon flux, as also found by Funsten et al. (2015) . 3.2.2. Comparing simulated and IBEX ribbon geometry Fig. 3 Simulated ribbon flux from locations along the elliptical fits, as a function of azimuthal angle about the circularity plot center (negative to positive angle is counterclockwise in Fig. 2 ). In the left panels we show the ribbon flux at each energy (different rows) for the slow, intermediate, and fast SW (solid curves), as well as the heliolatitude location of the ribbon (dashed curves). The shaded regions correspond to locations of the ribbon lying within 35 heliolatitude. Notice that the left -axis is in scaling. In the right panels we show the components of the ribbon flux that originated from outward-propagating, primary ENAs born in the IHS, the supersonic SW (SSW), and the total. Fig. 4 Simulated angles between the line-of-sight view from IBEX and the local interstellar magnetic field vector, at distances of 20 au ( left ) and 200 au ( right ) from the heliopause (HP). We show the locus of points defined by (black dots), fit a circle to that locus of points (black curve), and plot the center of the fitted circle (black dot near the center of the plot). The frame of reference of these plots is the same as those shown in Fig. 2 . Table 2 Weighted averages of geometric properties. Notes. The IBEX data are from Funsten et al. (2013) . All results in this table are weighted over energy and circle/ellipse fits. The aim of this analysis is to determine if there is a significant dependence of the ribbon’s geometric properties on the SW speed and ENA energy. Since the draping of the LISM magnetic field is a function of distance from the heliopause (e.g., Grygorczuk et al. 2011 ; Pogorelov et al. 2011 ; Zirnstein et al. 2015a ), the energy of the parent SW and ENA distribution may affect the distances at which the majority of ribbon ENAs (observed at 1 au) originate. We
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