We present deep ( V \simeq 27 ) V - and I -band stellar photometry of G302 and G312 , two globular star clusters in the halo of M31 .
These data were obtained using the Hubble Space Telescope ’ s Wide Field/Planetary Camera 2 .
We find iron abundances of { [ Fe / H ] } = -1.85 \pm 0.12 for G302 and { [ Fe / H ] } = -0.56 \pm 0.03 for G312 , consistent with spectroscopic measurements .
The color–magnitude diagrams for each cluster show no evidence for an intermediate-aged population of stars , or a second parameter effect in the morphology of the horizontal branch .
G302 shows no evidence for a color gradient but the inner regions of G312 are bluer than the outer regions .
G312 shows no evidence of ellipticity or an extended halo of unbound stars .
G302 has a projected ellipticity of \epsilon = 0.195 \pm 0.012 with the projected major axis oriented towards the center of M31 .
G302 also shows evidence of an extended asymmetric stellar halo extending to at least twice the fitted Michie–King tidal radius .
The amount of mass beyond the tidal radius of G302 is consistent with the stellar escape rates which have been predicted by N -body simulations of globular clusters in the Galactic tidal field .