Acronym	gap
Name	great antiprism, grand antiprism, pentagonal double antiprismoid
Cross sections	©
Circumradius	(1+sqrt(5))/2 = 1.618034
Vertex figure	is a bitrapezoidal truncated icosahedron
General of army	(is itself convex)
Colonel of regiment	(is itself locally convex – uniform polychoral members: by cells: pap tet gap 20 300 )
External links

The great antiprism (gap) is a faceting of the hexacosachoron. The antiprism cells (pap) form 2 rings of 10 each.

As abstract polychoron gap is isomorphic to padiap, thereby replacing the pentagons by pentagrams, resp. replacing pap by starp. Also the verftex figures turn from asymmetric facetings of ike into such facetings of gike.

Incidence matrix

100 |   2   4   4 |  1   6   3  12 |  2   8   4 :(vf) bitrapezoidal truncated ike
----+-------------+----------------+-----------
  2 | 100   *   * |  1   2   1   0 |  2   2   0 :5gon edges
  2 |   * 200   * |  0   2   0   2 |  1   2   1 :lateral ap edges
  2 |   *   * 200 |  0   0   1   4 |  0   3   2 :edges joining the ap rings
----+-------------+----------------+-----------
  5 |   5   0   0 | 20   *   *   * |  2   0   0 :ap-ap 5gon
  3 |   1   2   0 |  * 200   *   * |  1   1   0 :ap-tet(adj) trig
  3 |   1   0   2 |  *   * 100   * |  0   2   0 :tet(adj)-tet(adj) trig (extending the 5gon)
  3 |   0   1   2 |  *   *   * 400 |  0   1   1 :tet(adj)-tet(isol) trig
----+-------------+----------------+-----------
 10 |  10  10   0 |  2  10   0   0 | 20   *   * :5ap (pap)
  4 |   1   2   3 |  0   1   1   2 |  * 200   * :tet(adjacent) = ap-tet(adj) 3pyr
  4 |   0   2   4 |  0   0   0   4 |  *   * 100 :tet(isolated) = lateral-ap-edges 2ap