## The modular curve $X_{101b}$

Curve name $X_{101b}$
Index $48$
Level $8$
Genus $0$
Does the subgroup contain $-I$? No
Generating matrices $\left[ \begin{matrix} 1 & 2 \\ 4 & 1 \end{matrix}\right], \left[ \begin{matrix} 1 & 0 \\ 0 & 5 \end{matrix}\right], \left[ \begin{matrix} 7 & 6 \\ 0 & 1 \end{matrix}\right], \left[ \begin{matrix} 5 & 2 \\ 0 & 1 \end{matrix}\right]$
Images in lower levels
 Level Index of image Corresponding curve $2$ $6$ $X_{8}$ $4$ $24$ $X_{25n}$
Meaning/Special name
Chosen covering $X_{101}$
Curves that $X_{101b}$ minimally covers
Curves that minimally cover $X_{101b}$
Curves that minimally cover $X_{101b}$ and have infinitely many rational points.
Model $\mathbb{P}^{1}$, a universal elliptic curve over an appropriate base is given by $y^2 = x^3 + A(t)x + B(t), \text{ where}$ $A(t) = -110592t^{8} + 55296t^{6} - 8640t^{4} + 432t^{2} - 27$ $B(t) = 14155776t^{12} - 10616832t^{10} + 2985984t^{8} - 387072t^{6} + 15552t^{4} + 1296t^{2} - 54$
Elliptic curve whose $2$-adic image is the subgroup $y^2 + xy + y = x^3 + x^2 - 70x - 205$, with conductor $210$
Generic density of odd order reductions $47/672$