These photos come from Mike Davis, a hardcore sci-fi nut who lives in San Diego. He and some pals went out to Buttercup Valley in 1982 and got to watch them film the Jabba Sail Barge sequence from Blue Harvest: Horror Beyond Imagination, a.k.a. Revenge of the Jedi a.k.a. Return of the Jedi.
Mike has posted his entire account of the adventure on the RPF boards here, a long with a few more pictures than what’s in this gallery. Head on over to their boards for the whole story and more awesome shots of the filming of Return of the Jedi.