The album's title is a reference to "The Unforgettable Fire", an art exhibit about the atomic bombing of Hiroshima. The album itself is signed by all members; Bono, The Edge, Larry Mullen JR & Adam Clayton. The album was signed on February 27th, 2009 in London.
The picture is dual authenticated by Richard Watson and Andrew David Holland. Richard Watson at the time would hire professional autograph hunters to seek out specific individuals. Richard Watson owned a long standing memorabilia and record shop in London and many bands at the time would visit his store to promote their albums. The signature was authenticated by Andrew David Holland.