\[J_{\nu}\left(\nu\sec\beta\right)\sim\left(\frac{2}{\pi\nu\tan\beta}\right)^{%
\frac{1}{2}}\*\left(\cos\xi\sum_{k=0}^{\infty}\frac{U_{2k}(i\cot\beta)}{\nu^{2%
k}}-i\sin\xi\sum_{k=0}^{\infty}\frac{U_{2k+1}(i\cot\beta)}{\nu^{2k+1}}\right),\]