## The modular curve $X_{87d}$

Curve name $X_{87d}$
Index $48$
Level $8$
Genus $0$
Does the subgroup contain $-I$? No
Generating matrices $\left[ \begin{matrix} 1 & 2 \\ 4 & 1 \end{matrix}\right], \left[ \begin{matrix} 1 & 0 \\ 0 & 5 \end{matrix}\right], \left[ \begin{matrix} 1 & 0 \\ 0 & 7 \end{matrix}\right], \left[ \begin{matrix} 5 & 2 \\ 0 & 1 \end{matrix}\right]$
Images in lower levels
 Level Index of image Corresponding curve $2$ $6$ $X_{8}$ $4$ $24$ $X_{25h}$
Meaning/Special name
Chosen covering $X_{87}$
Curves that $X_{87d}$ minimally covers
Curves that minimally cover $X_{87d}$
Curves that minimally cover $X_{87d}$ and have infinitely many rational points.
Model $\mathbb{P}^{1}$, a universal elliptic curve over an appropriate base is given by $y^2 = x^3 + A(t)x + B(t), \text{ where}$ $A(t) = -432t^{8} - 864t^{6} - 540t^{4} - 108t^{2} - 27$ $B(t) = -3456t^{12} - 10368t^{10} - 11664t^{8} - 6048t^{6} - 972t^{4} + 324t^{2} + 54$
Elliptic curve whose $2$-adic image is the subgroup $y^2 = x^3 - x^2 - 20x$, with conductor $240$
Generic density of odd order reductions $9/112$