from to . However, most recent mass estimates have begun to converge to values of . Assuming the mean volume of , this equates to a bulk density of . Shape and spin pole The first published three-dimensional shape model for Psyche was derived from an analysis of numerous light curves. Since then, additional refinements to the shape have been made based on the inversion of lightcurves, adaptive optics observations, radar observations, thermal imaging, and occultations. The most recent models show that Psyche has a shape consistent with a Jacobi ellipsoid and dimensions within a few km of 278 km x 238 km x 171 km. Each shape model provides an estimate of the direction of the north pole (spin axis). All recent models for Psyche suggest it rotates about a pole pointed towards the ecliptic coordinates (long, lat) , , with a 3° uncertainty. This means that it is essentially tilted toward the ecliptic, with an axial tilt of 98°. Features Numerous features have been reported on Psyche. The largest of these are regions of mass-deficits relative to its nominal ellipsoid shape and are reminiscent of the Rheasilvia basin on 4 Vesta. In addition to the large-scale regions of mass-deficit, several apparent craters have been reported. Observers using the Very Large Telescope's adaptive optics SPHERE imager reported two large craters, on the order of 90 km across, which were provisionally named Meroe and Panthia , after the twin witches in the Roman novel Metamorphoses by Apuleius. Observers using the Arecibo Radar Telescope reported craters at the south pole (referred to as Delta), southern midlatitudes (referred to as Eros), and the north pole (referred to as Foxtrot). An analysis of the features present in several independent shape models suggests that craters Panthia and Eros are almost certainly real and Foxtrot is likely to be real. However, there is uncertainty over the existence of Meroe and Delta. Early lightcurve studies suggested that Psyche has large variations in its surface brightness. These variations became more evident when attempts were made to invert lightcurves to generate shape models. The most recent shape models based on lightcurve inversions simultaneously solve for surface albedo variations, and the resulting maps show regions where local albedo differs from the mean albedo by more than 20% in either direction. Notably, the Meroe crater coincides with an area much darker than the mean, and the Panthia crater coincides with