Since 1953, The Astrophysical Journal Supplement Series (often abbreviated to ApJS) has been published in conjunction with The Astrophysical Journal. It aims to supplement the material in the Journal. It currently (October 2006) publishes six volumes per year, with 2 issues per volume and 280 pages per issue. The journal and the supplement series are both currently published by the University of Chicago Press for the American Astronomical Society. From January 2009, publication will be transferred to Institute of Physics Publishing. This will follow the move of the society's Astronomical Journal in 2008. The reason for the changes were given by the Society as the increasing financial demands of the Press.
The Astrophysical Journal Letters (ApJL) is Part 2 of The Astrophysical Journal — a peer-reviewed express scientific journal.