Bounding $j$-invariant of integral points on $X_{\ns}^{+}(p)$

Abstract

For prime $p\ge 7$, by using Baker's method we obtain two explicit bounds in terms of $p$ for the $j$-invariant of an integral point on $X_{\ns}^{+}(p)$ which is the modular curve of level $p$ corresponding to the normalizer of a non-split Cartan subgroup of $\GL_2(\Z/p\Z)$.