Voyager Sighting (not the space probe)

[burkhard]

Since it's not an on-screen prop, but apparently an actual calculator used by the show's technical consultant (David Saltzberg, a physics and astronomy professor at UCLA), my guess is that it's most likely a 15C or perhaps an 11C.

And his professional bio at the university: http://www.physics.ucla.edu/~saltzberg/index.html