# Properties

 Label 1805a1 Conductor $1805$ Discriminant $2.123\times 10^{12}$ j-invariant $$\frac{318767104}{125}$$ CM no Rank $1$ Torsion structure $$\Z/{3}\Z$$

# Related objects

Show commands: Magma / Pari/GP / SageMath

## Simplified equation

 $$y^2+y=x^3+x^2-36581x+2679900$$ y^2+y=x^3+x^2-36581x+2679900 (homogenize, simplify) $$y^2z+yz^2=x^3+x^2z-36581xz^2+2679900z^3$$ y^2z+yz^2=x^3+x^2z-36581xz^2+2679900z^3 (dehomogenize, simplify) $$y^2=x^3-47409408x+125602337232$$ y^2=x^3-47409408x+125602337232 (homogenize, minimize)

sage: E = EllipticCurve([0, 1, 1, -36581, 2679900])

gp: E = ellinit([0, 1, 1, -36581, 2679900])

magma: E := EllipticCurve([0, 1, 1, -36581, 2679900]);

sage: E.short_weierstrass_model()

magma: WeierstrassModel(E);

## Mordell-Weil group structure

$$\Z \oplus \Z/{3}\Z$$

### Infinite order Mordell-Weil generator and height

sage: E.gens()

magma: Generators(E);

 $P$ = $$\left(-78, 2250\right)$$ (-78, 2250) $\hat{h}(P)$ ≈ $5.4053754122638225918627824939$

## Torsion generators

sage: E.torsion_subgroup().gens()

gp: elltors(E)

magma: TorsionSubgroup(E);

$$\left(120, 180\right)$$

## Integral points

sage: E.integral_points()

magma: IntegralPoints(E);

$$\left(-78, 2250\right)$$, $$\left(-78, -2251\right)$$, $$\left(120, 180\right)$$, $$\left(120, -181\right)$$

## Invariants

 sage: E.conductor().factor()  gp: ellglobalred(E)[1]  magma: Conductor(E); Conductor: $$1805$$ = $5 \cdot 19^{2}$ sage: E.discriminant().factor()  gp: E.disc  magma: Discriminant(E); Discriminant: $2122945380125$ = $5^{3} \cdot 19^{8}$ sage: E.j_invariant().factor()  gp: E.j  magma: jInvariant(E); j-invariant: $$\frac{318767104}{125}$$ = $2^{24} \cdot 5^{-3} \cdot 19$ Endomorphism ring: $\Z$ Geometric endomorphism ring: $$\Z$$ (no potential complex multiplication) Sato-Tate group: $\mathrm{SU}(2)$ Faltings height: $1.3299936923236280811361690656\dots$ Stable Faltings height: $-0.63296562712066555886984922233\dots$

## BSD invariants

 sage: E.rank()  magma: Rank(E); Analytic rank: $1$ sage: E.regulator()  magma: Regulator(E); Regulator: $5.4053754122638225918627824939\dots$ sage: E.period_lattice().omega()  gp: if(E.disc>0,2,1)*E.omega[1]  magma: (Discriminant(E) gt 0 select 2 else 1) * RealPeriod(E); Real period: $0.81048924377417577903307670077\dots$ sage: E.tamagawa_numbers()  gp: gr=ellglobalred(E); [[gr[4][i,1],gr[5][i][4]] | i<-[1..#gr[4][,1]]]  magma: TamagawaNumbers(E); Tamagawa product: $3$  = $1\cdot3$ sage: E.torsion_order()  gp: elltors(E)[1]  magma: Order(TorsionSubgroup(E)); Torsion order: $3$ sage: E.sha().an_numerical()  magma: MordellWeilShaInformation(E); Analytic order of Ш: $1$ (exact) sage: r = E.rank(); sage: E.lseries().dokchitser().derivative(1,r)/r.factorial()  gp: ar = ellanalyticrank(E); gp: ar[2]/factorial(ar[1])  magma: Lr1 where r,Lr1 := AnalyticRank(E: Precision:=12); Special value: $L'(E,1)$ ≈ $1.4603328767337430698402491790$

## Modular invariants

sage: E.q_eigenform(20)

gp: xy = elltaniyama(E);

gp: x*deriv(xy[1])/(2*xy[2]+E.a1*xy[1]+E.a3)

magma: ModularForm(E);

$$q - 2 q^{3} - 2 q^{4} - q^{5} - 4 q^{7} + q^{9} + 3 q^{11} + 4 q^{12} + 2 q^{13} + 2 q^{15} + 4 q^{16} + 6 q^{17} + O(q^{20})$$

 sage: E.modular_degree()  magma: ModularDegree(E); Modular degree: 4788 $\Gamma_0(N)$-optimal: yes Manin constant: 1

## Local data

This elliptic curve is not semistable. There are 2 primes of bad reduction:

sage: E.local_data()

gp: ellglobalred(E)[5]

magma: [LocalInformation(E,p) : p in BadPrimes(E)];

prime Tamagawa number Kodaira symbol Reduction type Root number ord($N$) ord($\Delta$) ord$(j)_{-}$
$5$ $1$ $I_{3}$ Non-split multiplicative 1 1 3 3
$19$ $3$ $IV^{*}$ Additive 1 2 8 0

## Galois representations

sage: rho = E.galois_representation();

sage: [rho.image_type(p) for p in rho.non_surjective()]

magma: [GaloisRepresentation(E,p): p in PrimesUpTo(20)];

The $\ell$-adic Galois representation has maximal image for all primes $\ell$ except those listed in the table below.

prime $\ell$ mod-$\ell$ image $\ell$-adic image
$3$ 3B.1.1 9.24.0.2

The image of the adelic Galois representation has level $1710$, index $144$, and genus $2$.

## $p$-adic regulators

sage: [E.padic_regulator(p) for p in primes(5,20) if E.conductor().valuation(p)<2]

Note: $p$-adic regulator data only exists for primes $p\ge 5$ of good ordinary reduction.

## Iwasawa invariants

 $p$ Reduction type $\lambda$-invariant(s) $\mu$-invariant(s) 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 ss ord nonsplit ord ord ord ord add ss ord ord ord ord ord ord 10,1 3 3 1 1 1 1 - 1,1 1 1 1 1 1 1 0,0 0 0 0 0 0 0 - 0,0 0 0 0 0 0 0

An entry - indicates that the invariants are not computed because the reduction is additive.

## Isogenies

This curve has non-trivial cyclic isogenies of degree $d$ for $d=$ 3.
Its isogeny class 1805a consists of 2 curves linked by isogenies of degree 3.

## Growth of torsion in number fields

The number fields $K$ of degree less than 24 such that $E(K)_{\rm tors}$ is strictly larger than $E(\Q)_{\rm tors}$ $\cong \Z/{3}\Z$ are as follows:

 $[K:\Q]$ $E(K)_{\rm tors}$ Base change curve $K$ $3$ 3.3.7220.1 $$\Z/6\Z$$ Not in database $6$ 6.6.260642000.1 $$\Z/2\Z \oplus \Z/6\Z$$ Not in database $6$ 6.0.3518667.2 $$\Z/3\Z \oplus \Z/3\Z$$ Not in database $9$ 9.3.1270238787.1 $$\Z/9\Z$$ Not in database $12$ Deg 12 $$\Z/12\Z$$ Not in database $18$ 18.0.43564677551979246963.1 $$\Z/3\Z \oplus \Z/9\Z$$ Not in database $18$ 18.0.2788139363326671805632000000.1 $$\Z/3\Z \oplus \Z/6\Z$$ Not in database

We only show fields where the torsion growth is primitive. For fields not in the database, click on the degree shown to reveal the defining polynomial.