\[W'\left(-\tfrac{1}{2}\mu^{2},\mu t\sqrt{2}\right)\sim-\frac{\mu}{\sqrt{2}}l(%
\mu)(t^{2}+1)^{\frac{1}{4}}\left(\sin\overline{\sigma}\sum_{s=0}^{\infty}\frac%
{(-1)^{s}\overline{v}_{2s}(t)}{(t^{2}+1)^{3s}\mu^{4s}}+\cos\overline{\sigma}%
\sum_{s=0}^{\infty}\frac{(-1)^{s}\overline{v}_{2s+1}(t)}{(t^{2}+1)^{3s+\frac{3%
}{2}}\mu^{4s+2}}\right),\]