Invariants
Level: | $28$ | $\SL_2$-level: | $4$ | ||||
Index: | $24$ | $\PSL_2$-index: | $12$ | ||||
Genus: | $0 = 1 + \frac{ 12 }{12} - \frac{ 0 }{4} - \frac{ 0 }{3} - \frac{ 4 }{2}$ | ||||||
Cusps: | $4$ (of which $2$ are rational) | Cusp widths | $2^{2}\cdot4^{2}$ | Cusp orbits | $1^{2}\cdot2$ | ||
Elliptic points: | $0$ of order $2$ and $0$ of order $3$ | ||||||
$\Q$-gonality: | $1$ | ||||||
$\overline{\Q}$-gonality: | $1$ | ||||||
Rational cusps: | $2$ | ||||||
Rational CM points: | none |
Other labels
Cummins and Pauli (CP) label: | 4E0 |
Rouse, Sutherland, and Zureick-Brown (RSZB) label: | 28.24.0.22 |
Level structure
$\GL_2(\Z/28\Z)$-generators: | $\begin{bmatrix}5&12\\14&23\end{bmatrix}$, $\begin{bmatrix}20&27\\25&6\end{bmatrix}$ |
Contains $-I$: | no $\quad$ (see 28.12.0.h.1 for the level structure with $-I$) |
Cyclic 28-isogeny field degree: | $8$ |
Cyclic 28-torsion field degree: | $48$ |
Full 28-torsion field degree: | $8064$ |
Models
This modular curve is isomorphic to $\mathbb{P}^1$.
Rational points
This modular curve has infinitely many rational points, including 556 stored non-cuspidal points.
Maps to other modular curves
$j$-invariant map of degree 12 to the modular curve $X(1)$ :
$\displaystyle j$ | $=$ | $\displaystyle \frac{1}{2^2\cdot7}\cdot\frac{(28x-y)^{12}(200704x^{4}+6272x^{2}y^{2}+y^{4})^{3}}{y^{2}x^{2}(28x-y)^{12}(448x^{2}-y^{2})^{4}}$ |
Modular covers
This modular curve minimally covers the modular curves listed below.
Covered curve | Level | Index | Degree | Genus | Rank |
---|---|---|---|---|---|
$X_1(4)$ | $4$ | $2$ | $2$ | $0$ | $0$ |
28.12.0-4.c.1.1 | $28$ | $2$ | $2$ | $0$ | $0$ |
This modular curve is minimally covered by the modular curves in the database listed below.