  This is a note on MacPherson's local Euler obstruction, which plays an
important role recently in Donaldson-Thomas theory by the work of Behrend.
  We introduce MacPherson's original definition, and prove that it is
equivalent to the algebraic definition used by Behrend, following the method of
Gonzalez-Sprinberg. We also give a formula of the local Euler obstruction in
terms of Lagrangian intersections. As an application, we consider a scheme or
DM stack $X$ admitting a symmetric obstruction theory. Furthermore we assume
that there is a $\CC^*$ action on $X$, which makes the obstruction theory
$\CC^*$-equivariant. The $\CC^*$-action on the obstruction theory naturally
gives rise to a cosection map in the sense of Kiem-Li. We prove that Behrend's
weighted Euler characteristic of $X$ is the same as Kiem-Li localized invariant
of $X$ by the $\CC^*$-action.
