These transparencies are from the archive of Astra Image Corp, the art department created for Star Trek: The Motion Picture by Robert Abel & Associates.
Each of these transparencies measures 10.25 in. x 12.5 in. Prior to our acquisition of this set on March 26, 2015, they were held in another private collection.
Note: There are several of these (10?) printed in the negative that I have yet to find a good way to photograph. I’ll make an additional post with those once I get to that.