The AAS is pleased to released the latest version of the LaTeX class file AASTeX, version 6.3. You can read about the new features that were included in AASTeX 6.3 here.
AASTeX v6.3 is available locally and on CTAN.
The AAS Journals Template in Overleaf has been updated to the v6.3 classfile and sample documentation.
The publishing team received very helpful feedback from authors in response to previous versions, and your requests have now been incorporated into an updated version. AASTeX 6.3 and the updated user guide are both available now.