  We introduce the palindromic automorphism group and the palindromic Torelli
group of a right-angled Artin group A_G. The palindromic automorphism group Pi
A_G is related to the principal congruence subgroups of GL(n,Z) and to the
hyperelliptic mapping class group of an oriented surface, and sits inside the
centraliser of a certain hyperelliptic involution in Aut(A_G). We obtain finite
generating sets for Pi A_G and for this centraliser, and determine precisely
when these two groups coincide. We also find generators for the palindromic
Torelli group.
