> the modern hard drives are reaaly big and it's possible to copy the
> complete SA (and other catalogs) to the hard drive.
>
> Unfortunately Guide only accept a letter for the USNO dataset. It would be
> nice if Guide also accept a folder, so that I can put the catalogs e.g. in
> folder C:\USNOA2.

There are ways around that - assign a virtual drive letter to that
subdirectory, with either the "subst" or the "net use" command.