  The Fisher-Bingham system is a system of linear partial differential
equations satisfied by the Fisher-Bingham integral for the $n$-dimensional
sphere $S^n$. The system is given in [Nakayama et al. (2011), Theorem 2] and it
is shown that it is a holonomic system [Koyama]. We show that the holonomic
rank of the system is equal to $2n+2$.
