VGIT Presentation of the Second Flip of M ¯ 2 , 1

Abstract

We perform a variation of geometric invariant theory stability analysis for 2nd Hilbert points of bi-log-canonically embedded pointed curves of genus 2 . As a result, we give a GIT construction of the log canonical models M ¯ 2 , 1 ( α ) for α = 2 / 3 ± ϵ and obtain a VGIT presentation of the second flip in the Hassett–Keel program for the moduli space of pointed genus 2 curves.