Properties

Label 84.64.2-28.a.1.7
Level $84$
Index $64$
Genus $2$
Cusps $2$
$\Q$-cusps $2$

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Invariants

Level: $84$ $\SL_2$-level: $28$ Newform level: $112$
Index: $64$ $\PSL_2$-index:$32$
Genus: $2 = 1 + \frac{ 32 }{12} - \frac{ 0 }{4} - \frac{ 2 }{3} - \frac{ 2 }{2}$
Cusps: $2$ (all of which are rational) Cusp widths $4\cdot28$ Cusp orbits $1^{2}$
Elliptic points: $0$ of order $2$ and $2$ of order $3$
Analytic rank: not computed
$\Q$-gonality: $2$
$\overline{\Q}$-gonality: $2$
Rational cusps: $2$
Rational CM points: none

Other labels

Cummins and Pauli (CP) label: 28A2

Level structure

$\GL_2(\Z/84\Z)$-generators: $\begin{bmatrix}48&17\\61&32\end{bmatrix}$, $\begin{bmatrix}72&11\\49&83\end{bmatrix}$, $\begin{bmatrix}73&7\\60&83\end{bmatrix}$, $\begin{bmatrix}73&62\\55&3\end{bmatrix}$
Contains $-I$: no $\quad$ (see 28.32.2.a.1 for the level structure with $-I$)
Cyclic 84-isogeny field degree: $24$
Cyclic 84-torsion field degree: $576$
Full 84-torsion field degree: $145152$

Models

Embedded model Embedded model in $\mathbb{P}^{3}$

$ 0 $ $=$ $ 2 x^{2} y + 2 x^{2} z + x^{2} w - x y^{2} - x y z - x y w + 3 x z w - x w^{2} + 2 y^{3} + y^{2} z + \cdots + y z w $
$=$ $2 x^{2} y + 2 x^{2} z - x y^{2} + 4 x y z - 2 x y w - 2 x z^{2} + x z w - 3 y^{3} + 3 y^{2} z - y z^{2}$
$=$ $2 x^{2} y + 2 x^{2} z + 3 x^{2} w + 9 x y^{2} - 5 x y z - x y w + x z w - 3 y^{3} + 3 y^{2} z - y z^{2}$
$=$ $2 x^{2} y + 2 x^{2} z - x y^{2} + 4 x y z + x y w - 2 x z^{2} + x z w + 7 y^{3} - 6 y^{2} z + \cdots + y z^{2}$
$=$$\cdots$
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Singular plane model Singular plane model

$ 0 $ $=$ $ 200 x^{4} + 70 x^{3} y - 30 x^{3} z + 38 x^{2} y^{2} - 54 x^{2} y z - 37 x^{2} z^{2} + 6 x y^{3} + \cdots - z^{4} $
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Weierstrass model Weierstrass model

$ y^{2} $ $=$ $ x^{6} - 2x^{5} - 4x^{4} - 4x^{3} - 4x^{2} - 2x + 1 $
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Rational points

This modular curve has rational points, including 2 rational_cusps and 2 known non-cuspidal non-CM points. The following are the known rational points on this modular curve (one row per $j$-invariant).

Elliptic curve CM $j$-invariant $j$-heightPlane modelWeierstrass modelEmbedded model
no$\infty$ $0.000$
338.c2 no$\tfrac{351}{4}$ $= 2^{-2} \cdot 3^{3} \cdot 13$$5.861$$(1/4:0:1)$$(0:1:1)$$(1/4:1/2:1:0)$
338.c1 no$\tfrac{-38575685889}{16384}$ $= -1 \cdot 2^{-14} \cdot 3^{3} \cdot 13 \cdot 479^{3}$$24.376$$(1/5:7/30:1)$$(1:1:0)$$(-2/7:6/7:15/7:1)$

Maps to other modular curves

$j$-invariant map of degree 32 from the embedded model of this modular curve to the modular curve $X(1)$ :

$\displaystyle j$ $=$ $\displaystyle -\frac{1}{5}\cdot\frac{130614400000000000x^{7}-99881600000000000x^{6}z-55977600000000000x^{6}w-122931200000000000x^{5}zw-477024800000000000x^{5}w^{2}-1112064800000000000x^{4}zw^{2}+197387926310400000x^{4}w^{3}+394110356677800000x^{3}zw^{3}+277763466735600000x^{3}w^{4}+1301844259231725200x^{2}zw^{4}-207339576407639620x^{2}w^{5}+115528051941719310xyw^{5}+1389879324467200000xz^{6}-1695807243571700000xz^{5}w+1251162780491750000xz^{4}w^{2}-880869154427673600xz^{3}w^{3}+502320398906296910xz^{2}w^{4}-374656451590002785xzw^{5}+96371895233205741xw^{6}+1223471152367100000yz^{6}-2759228863259750000yz^{5}w+2038438633988750000yz^{4}w^{2}-682108298581565450yz^{3}w^{3}-190611837352195895yz^{2}w^{4}+340220211204822902yzw^{5}-74743987053512293yw^{6}-960670392456600000z^{7}+2382474277455300000z^{6}w-2197883256738400000z^{5}w^{2}+991193000528510500z^{4}w^{3}-64080431766090230z^{3}w^{4}-257052774107024586z^{2}w^{5}+114287600000000000zw^{6}-15366400000000000w^{7}}{133280000000000x^{5}w^{2}+297920000000000x^{4}zw^{2}-56255270400000x^{4}w^{3}-102093447400000x^{3}zw^{3}+79252400000000x^{3}w^{4}+315695033018800x^{2}zw^{4}-50957507310780x^{2}w^{5}-5305822059110xyw^{5}+8482252800000xz^{6}-37149760620000xz^{5}w+91090806450000xz^{4}w^{2}-164844693518400xz^{3}w^{3}+167630755828290xz^{2}w^{4}-61374963333915xzw^{5}+8818499575479xw^{6}+2084692260000yz^{6}+18129734910000yz^{5}w-76396073950000yz^{4}w^{2}+134395684607450yz^{3}w^{3}-72650245298005yz^{2}w^{4}+29690063656938yzw^{5}-3779481440767yw^{6}+213496920000z^{7}-11664298100000z^{6}w+40076845200000z^{5}w^{2}-67994028658500z^{4}w^{3}+31663349175630z^{3}w^{4}-7558962881534z^{2}w^{5}}$

Map of degree 1 from the embedded model of this modular curve to the plane model of the modular curve 28.32.2.a.1 :

$\displaystyle X$ $=$ $\displaystyle y$
$\displaystyle Y$ $=$ $\displaystyle w$
$\displaystyle Z$ $=$ $\displaystyle 2z$

Equation of the image curve:

$0$ $=$ $ 200X^{4}+70X^{3}Y+38X^{2}Y^{2}+6XY^{3}-30X^{3}Z-54X^{2}YZ-24XY^{2}Z-37X^{2}Z^{2}+23XYZ^{2}+3Y^{2}Z^{2}+12XZ^{3}-3YZ^{3}-Z^{4} $

Map of degree 1 from the embedded model of this modular curve to the Weierstrass model of the modular curve 28.32.2.a.1 :

$\displaystyle X$ $=$ $\displaystyle -\frac{1}{5}yw$
$\displaystyle Y$ $=$ $\displaystyle \frac{3}{5}y^{6}-\frac{86}{75}y^{5}z-\frac{13}{75}y^{5}w+\frac{286}{375}y^{4}z^{2}+\frac{176}{375}y^{4}zw-\frac{41}{375}y^{4}w^{2}-\frac{16}{75}y^{3}z^{3}-\frac{6}{25}y^{3}z^{2}w+\frac{2}{25}y^{3}zw^{2}+\frac{8}{375}y^{2}z^{4}+\frac{4}{125}y^{2}z^{3}w-\frac{2}{125}y^{2}z^{2}w^{2}$
$\displaystyle Z$ $=$ $\displaystyle -y^{2}+\frac{2}{5}yz$

Modular covers

The following modular covers realize this modular curve as a fiber product over $X(1)$.

Factor curve Level Index Degree Genus Rank
$X_{\mathrm{ns}}^+(4)$ $4$ $16$ $8$ $0$ $0$
21.16.0-7.a.1.1 $21$ $4$ $4$ $0$ $0$

This modular curve minimally covers the modular curves listed below.

Covered curve Level Index Degree Genus Rank
21.16.0-7.a.1.1 $21$ $4$ $4$ $0$ $0$

This modular curve is minimally covered by the modular curves in the database listed below.

Covering curve Level Index Degree Genus
84.128.3-28.a.1.5 $84$ $2$ $2$ $3$
84.128.3-28.b.1.5 $84$ $2$ $2$ $3$
84.128.3-28.c.1.4 $84$ $2$ $2$ $3$
84.128.3-84.c.1.5 $84$ $2$ $2$ $3$
84.128.3-28.d.1.4 $84$ $2$ $2$ $3$
84.128.3-84.d.1.2 $84$ $2$ $2$ $3$
84.128.3-84.h.1.7 $84$ $2$ $2$ $3$
84.128.3-84.i.1.6 $84$ $2$ $2$ $3$
84.192.6-28.k.1.3 $84$ $3$ $3$ $6$
84.192.6-28.k.2.1 $84$ $3$ $3$ $6$
84.192.6-28.l.1.7 $84$ $3$ $3$ $6$
84.192.6-28.m.1.7 $84$ $3$ $3$ $6$
84.192.8-84.i.1.12 $84$ $3$ $3$ $8$
84.256.9-84.a.1.16 $84$ $4$ $4$ $9$
84.448.15-28.e.1.4 $84$ $7$ $7$ $15$
168.128.3-56.a.1.8 $168$ $2$ $2$ $3$
168.128.3-56.b.1.4 $168$ $2$ $2$ $3$
168.128.3-56.c.1.8 $168$ $2$ $2$ $3$
168.128.3-56.d.1.6 $168$ $2$ $2$ $3$
168.128.3-168.e.1.13 $168$ $2$ $2$ $3$
168.128.3-168.f.1.10 $168$ $2$ $2$ $3$
168.128.3-168.m.1.13 $168$ $2$ $2$ $3$
168.128.3-168.n.1.14 $168$ $2$ $2$ $3$
168.256.9-56.a.1.1 $168$ $4$ $4$ $9$
252.192.6-252.bk.1.3 $252$ $3$ $3$ $6$
252.192.6-252.bk.2.5 $252$ $3$ $3$ $6$
252.192.6-252.bl.1.12 $252$ $3$ $3$ $6$
252.192.6-252.bl.2.10 $252$ $3$ $3$ $6$
252.192.6-252.bm.1.16 $252$ $3$ $3$ $6$
252.192.6-252.bm.2.16 $252$ $3$ $3$ $6$