## The modular curve $X_{27c}$

Curve name $X_{27c}$
Index $24$
Level $8$
Genus $0$
Does the subgroup contain $-I$? No
Generating matrices $\left[ \begin{matrix} 5 & 0 \\ 4 & 1 \end{matrix}\right], \left[ \begin{matrix} 1 & 2 \\ 0 & 1 \end{matrix}\right], \left[ \begin{matrix} 7 & 7 \\ 4 & 1 \end{matrix}\right], \left[ \begin{matrix} 3 & 0 \\ 4 & 3 \end{matrix}\right]$
Images in lower levels
 Level Index of image Corresponding curve $2$ $3$ $X_{6}$ $4$ $12$ $X_{27}$
Meaning/Special name
Chosen covering $X_{27}$
Curves that $X_{27c}$ minimally covers
Curves that minimally cover $X_{27c}$
Curves that minimally cover $X_{27c}$ and have infinitely many rational points.
Model $\mathbb{P}^{1}$, a universal elliptic curve over an appropriate base is given by $y^2 = x^3 + A(t)x + B(t), \text{ where}$ $A(t) = -27648t^{8} + 82944t^{6} + 44928t^{4} + 5184t^{2} - 108$ $B(t) = 1769472t^{12} + 15925248t^{10} + 7630848t^{8} - 476928t^{4} - 62208t^{2} - 432$
Elliptic curve whose $2$-adic image is the subgroup $y^2 = x^3 - x^2 + 367x - 28863$, with conductor $2400$
Generic density of odd order reductions $289/1792$