Properties

Label 84.384.9-42.c.3.14
Level $84$
Index $384$
Genus $9$
Cusps $16$
$\Q$-cusps $4$

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Invariants

Level: $84$ $\SL_2$-level: $84$ Newform level: $42$
Index: $384$ $\PSL_2$-index:$192$
Genus: $9 = 1 + \frac{ 192 }{12} - \frac{ 0 }{4} - \frac{ 0 }{3} - \frac{ 16 }{2}$
Cusps: $16$ (of which $4$ are rational) Cusp widths $1^{2}\cdot2^{2}\cdot3^{2}\cdot6^{2}\cdot7^{2}\cdot14^{2}\cdot21^{2}\cdot42^{2}$ Cusp orbits $1^{4}\cdot2^{6}$
Elliptic points: $0$ of order $2$ and $0$ of order $3$
Analytic rank: not computed
$\Q$-gonality: $4 \le \gamma \le 9$
$\overline{\Q}$-gonality: $4 \le \gamma \le 9$
Rational cusps: $4$
Rational CM points: none

Other labels

Cummins and Pauli (CP) label: 42E9

Level structure

$\GL_2(\Z/84\Z)$-generators: $\begin{bmatrix}21&40\\4&69\end{bmatrix}$, $\begin{bmatrix}32&51\\47&28\end{bmatrix}$, $\begin{bmatrix}34&5\\39&26\end{bmatrix}$, $\begin{bmatrix}68&67\\53&12\end{bmatrix}$, $\begin{bmatrix}83&10\\24&55\end{bmatrix}$
Contains $-I$: no $\quad$ (see 42.192.9.c.3 for the level structure with $-I$)
Cyclic 84-isogeny field degree: $2$
Cyclic 84-torsion field degree: $48$
Full 84-torsion field degree: $24192$

Models

Canonical model in $\mathbb{P}^{ 8 }$ defined by 21 equations

$ 0 $ $=$ $ x z + x t + x r + x s - y v - y r - y s + u v + u r + u s $
$=$ $x^{2} + x z - x w - x t + x r - x s - z t + t^{2} - t r + t s$
$=$ $x z + x t + x u - 2 x v + x r - x s - y v - y r - y s - u v + v^{2} + v s$
$=$ $x^{2} - x y - 2 x w - x u - x r - x s + y v - z v + t v + u v - v^{2}$
$=$$\cdots$
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Singular plane model Singular plane model

$ 0 $ $=$ $ 2304 x^{12} + 288 x^{11} y - 5184 x^{11} z + 408 x^{10} y^{2} + 5292 x^{10} y z + 20196 x^{10} z^{2} + \cdots + 63 z^{12} $
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Rational points

This modular curve has 4 rational cusps but no known non-cuspidal rational points. The following are the coordinates of the rational cusps on this modular curve.

Canonical model
$(1:0:1:1:2:-3:-1:2:1)$, $(-1/2:0:-1/2:-1/2:-1:0:-1:1/2:1)$, $(1:0:-1/2:-1/2:1/2:0:-1:-1:1)$, $(1:0:-1/2:-1/2:1/2:0:2:-1:1)$

Maps to other modular curves

Map of degree 2 from the canonical model of this modular curve to the canonical model of the modular curve $X_0(42)$ :

$\displaystyle X$ $=$ $\displaystyle -x$
$\displaystyle Y$ $=$ $\displaystyle t$
$\displaystyle Z$ $=$ $\displaystyle -z$
$\displaystyle W$ $=$ $\displaystyle -w$
$\displaystyle T$ $=$ $\displaystyle -z+t-r+s$

Equation of the image curve:

$0$ $=$ $ X^{2}-XW+XT+YT $
$=$ $ X^{2}+XZ-Z^{2}+2XW-2ZW-W^{2}+YT $
$=$ $ X^{2}+Y^{2}+2YZ+Z^{2}+2YW+2ZW-YT-ZT $

Map of degree 1 from the canonical model of this modular curve to the plane model of the modular curve 42.192.9.c.3 :

$\displaystyle X$ $=$ $\displaystyle x$
$\displaystyle Y$ $=$ $\displaystyle 3s$
$\displaystyle Z$ $=$ $\displaystyle v$

Equation of the image curve:

$0$ $=$ $ 2304X^{12}+288X^{11}Y+408X^{10}Y^{2}+48X^{9}Y^{3}+25X^{8}Y^{4}+2X^{7}Y^{5}+X^{6}Y^{6}-5184X^{11}Z+5292X^{10}YZ-303X^{9}Y^{2}Z+687X^{8}Y^{3}Z-19X^{7}Y^{4}Z+33X^{6}Y^{5}Z-2X^{5}Y^{6}Z+20196X^{10}Z^{2}-10899X^{9}YZ^{2}+7263X^{8}Y^{2}Z^{2}-1398X^{7}Y^{3}Z^{2}+520X^{6}Y^{4}Z^{2}-75X^{5}Y^{5}Z^{2}+3X^{4}Y^{6}Z^{2}-29718X^{9}Z^{3}+37152X^{8}YZ^{3}-13815X^{7}Y^{2}Z^{3}+5295X^{6}Y^{3}Z^{3}-1102X^{5}Y^{4}Z^{3}+103X^{4}Y^{5}Z^{3}-2X^{3}Y^{6}Z^{3}+53703X^{8}Z^{4}-50787X^{7}YZ^{4}+28494X^{6}Y^{2}Z^{4}-8589X^{5}Y^{3}Z^{4}+1321X^{4}Y^{4}Z^{4}-75X^{3}Y^{5}Z^{4}+X^{2}Y^{6}Z^{4}-49248X^{7}Z^{5}+66528X^{6}YZ^{5}-33669X^{5}Y^{2}Z^{5}+8247X^{4}Y^{3}Z^{5}-904X^{3}Y^{4}Z^{5}+33X^{2}Y^{5}Z^{5}+41607X^{6}Z^{6}-52434X^{5}YZ^{6}+24120X^{4}Y^{2}Z^{6}-4755X^{3}Y^{3}Z^{6}+385X^{2}Y^{4}Z^{6}-7XY^{5}Z^{6}-13365X^{5}Z^{7}+21060X^{4}YZ^{7}-9819X^{3}Y^{2}Z^{7}+1740X^{2}Y^{3}Z^{7}-91XY^{4}Z^{7}-9639X^{4}Z^{8}+1485X^{3}YZ^{8}+2079X^{2}Y^{2}Z^{8}-399XY^{3}Z^{8}+7Y^{4}Z^{8}+14643X^{3}Z^{9}-4734X^{2}YZ^{9}-294XY^{2}Z^{9}+42Y^{3}Z^{9}-6642X^{2}Z^{10}+1323XYZ^{10}+21Y^{2}Z^{10}+756XZ^{11}-126YZ^{11}+63Z^{12} $

Modular covers

This modular curve minimally covers the modular curves listed below.

Covered curve Level Index Degree Genus Rank
84.192.5-42.a.1.17 $84$ $2$ $2$ $5$ $?$
84.192.5-42.a.1.47 $84$ $2$ $2$ $5$ $?$