\([24, 12, 8]\) Extended Golay code

\([24, 12, 8]\) Extended Golay code [1]

Description

A self-dual \([24, 12, 8]\) code that is obtained from the Golay code by adding a parity check. Equivalently, puncturing any coordinate yields the \([23,12,7]\) Golay code. Up to equivalence, it is unique for its parameters [2], and it is the unique \([24,12,8]\) extremal Type II code [3; Rems. 4.3.10 and 4.3.11].

The automorphism group of the extended Golay code is the Mathieu group \(\mathcal{M}_{24}\), a sporadic simple group [3; Rem. 4.3.11].

Decoding

Majority decoding [4].Decoder using the hexacode [5].The extended Golay code has a trellis representation and can thus be decoded using trellis decoding [6,7].

Realizations

Voyager 1 and 2 spacecraft, transmitting hundreds of color pictures of Jupiter and Saturn in their 1979, 1980, and 1981 fly-bys [8].American military standards for automatic link establishment in high frequency radio systems [9].

Notes

See Ref. [10; Sec. 1.13][11; Sec. 2.5] for an introduction to Golay codes.

Cousins

Orthogonal array (OA)— The extended Golay code is an orthogonal array of strength 7 [12; Exam. 1].
Self-dual linear code— The extended Golay code is the unique \([24,12,8]\) code, and in particular the unique self-dual doubly even code with those parameters [2][3; Rem. 4.3.11].
\([16,5,8]\) first-order RM code— The \([16,5,8]\) first-order RM code is a subcode of the extended Golay code [13; Ch. 5, pg. 146].
\([8,4,4]\) extended Hamming code— The extended Golay code can be constructed from two suitably chosen extended Hamming \([8,4,4]\) codes using the \(|a+x|b+x|a+b+x|\) construction [14; pg. 588].
Binary quadratic-residue (QR) code— The extended Golay code is an extended binary quadratic-residue code [14; Ch. 16].
Icosahedron code— The parity bits of the extended Golay code can be visualized to lie on the vertices of the icosahedron; see [15] for more details. To construct the code, one can use the great dodecahedron to generate codewords by placing message bits on the faces and calculating the parity bits that live on the 12 vertices of the inner icosahedron.
Dodecahedron code— The parity bits of the extended Golay code can be visualized to lie on the vertices of the icosahedron; see [15] for more details. To construct the code, one can use the great dodecahedron to generate codewords by placing message bits on the faces and calculating the parity bits that live on the 12 vertices of the inner icosahedron.
\([23, 12, 7]\) Golay code— The extended Golay code is an extension of the Golay code by a parity-check bit.
\(\Lambda_{24}\) Leech lattice— Two copies of the 24-dimensional packing obtained from the extended Golay code can be fitted together without overlap to form the Leech lattice [13; Ch. 5, pg. 145]. Half of the lattice can be obtained using Construction \(B^{\star}\) [16; Exam. 10.7.3].
Niemeier lattice— The extended Golay code is the glue code for the Niemeier lattice \(A_1^{24}\) [13; Ch. 16, pg. 408].
Combinatorial design— The supports of the weight-eight codewords of the extended Golay code support the Steiner system \(S(5,8,24)\) [17,18][13; pg. 89][13; Ch. 10, pg. 276]. Its blocks are called octads.
\((16,256,6)\) Nordstrom-Robinson (NR) code— The NR code can be constructed using the extended Golay code by first selecting a set of codewords satisfying certain conditions and then deleting specific coordinates [14; pg. 73].
\([12,6,6]_3\) Extended ternary Golay code— The extended ternary Golay code is the ternary counterpart of the extended Golay code.
\([6,3,4]_4\) Hexacode— Extended Golay codewords can be obtained from hexacodewords [13]. The hexacode can be used to decode the extended Golay code [5].
Pseudo Golay code— The mod-two reduction (mapping \(0,1,2,3\) to \(0,1,0,1\)) of all pseudo Golay codes yields the extended Golay code; see Ref. [19].
Extended quaternary Golay code— Codewords of the extended quaternary Golay code with entries 0 and 2 are of the form \(2c\), where \(c\) is a codeword of the extended Golay code. Its mod-two reduction (mapping \(0,1,2,3\) to \(0,1,0,1\)) also yields the extended Golay code [19,20]. The quaternary Golay code can be constructed from the extended Golay code by Hensel lifting to \(\mathbb{Z}_4\) [20,21][13; 3rd Ed., pg. xxxiii].
\([[11,1,5]]_4\) Galois-qudit CSS code— The \([[11,1,5]]_4\) code is constructed from the expurgated QR code obtained by shortening the \([12,6,6]_4\) extended QR code. The binary image of that extended QR code is the extended Golay code [22][14; Ch. 16].

Member of code lists

Primary Hierarchy

Classical Domain

Binary Kingdom

Binary codeECC

Binary group-orbit codeECC

Linear binary codeLinear \(q\)-ary Linear code over \(\mathbb{Z}_q\) ECC

\([2m+2,m+1]\) Karlin codeSelf-dual linear Self-dual additive Linear \(q\)-ary ECC

Parents

\([2m+2,m+1]\) Karlin code

The extended Golay code is equivalent to the Karlin double circulant code for \(m=11\) [14; Ch. 16].

Quasi-perfect codeECC

The extended Golay code has covering radius four, one more than its packing radius, and is therefore quasi-perfect.

\(q\)-ary sharp configurationOA Sharp configuration Universally optimal ECC \(t\)-design

The extended Golay code is a sharp configuration [23; Table 12.1].

Group-algebra codeLinear \(q\)-ary ECC

The extended Golay code is a group-algebra code for various groups [24–26]; see [28][27; Exam. 16.5.1].

Lexicographic codeECC

The extended Golay code is a lexicode [29,30][14; pg. 327].

\([24, 12, 8]\) Extended Golay code

References

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Page edit log

Victor V. Albert (2026-10-13) — most recent
Victor V. Albert (2026-06-08)
Vikram Elijah Amin (2025-01-07)

Cite as:

“\([24, 12, 8]\) Extended Golay code”, The Error Correction Zoo (V. V. Albert & P. Faist, eds.), 2026. https://errorcorrectionzoo.org/c/extended_golay, arXiv:2606.11484

Github: https://github.com/errorcorrectionzoo/eczoo_data/edit/main/codes/classical/bits/cyclic/quad_residue/extended_golay.yml.