Asymptotic expansion for the Keesom integral

It is proved that the asymptotic series for the leading term K∞(a) of the Keesom integral K(a) obtained by us in a previous paper (2004 J. Phys. A: Math. Gen. 37 9677), in order to evaluate K(a) for large values of the interaction parameter a, is indeed an asymptotic expansion of K(a) itself.