Stephen,

The Copyright Act of 1976 (enacted 1978) gives the following rights to
artists: the right to protect the work for the artist's life + 50 years (I
guess recently law has been enacted to make that artist's life + 70 years for
some works), the right to distribute the work to the public, the right to
display, the right to perform, and the right to derivative works (which may in
themselves be copyrightable).  All, none, or some of these rights can be
transferred at the time of a sale.  In essence, the museum must be very
careful w/ copyright issues and therefore should have the exact rights
transferred to said museum documented in writing.  One should also consult
legal counsel regarding fair use issues.  The Berne Convention (1988) and VARA
(Visual Artists Rights Act 1990, enacted 1991) should also be looked into.

Ginger M. Young