  A recent paper [Jokela et al, arxiv:0806.1491 9 June 2008] contains a surmise
about an expectation value in a Coulomb gas which interacts with an additional
charge xi that sits at a fixed position. Here I demonstrate the validity of the
surmised expression and extend it to a certain class of higher cumulants. The
calculation is based on the analogy to statistical averages in the circular
unitary ensemble of random-matrix theory and exploits properties of orthogonal
polynomials on the unit circle.
