GAP package Carat: Interface to CARAT, a crystallographic groups package. This package provides GAP interface routines to some of the stand-alone programs of CARAT, a package for the computation with crystallographic groups. CARAT is to a large extent complementary to the GAP package Cryst. In particular, it provides routines for the computation of normalizers and conjugators of finite unimodular groups in GL(n,Z), and routines for the computation of Bravais groups, which are all missing in Cryst. A catalog of Bravais groups up to dimension 6 is also provided.