Thanks for reading guys.
Here's a graphic of the occultation in July (6hr intervals).
Brightness exaggerated. Note that the star closely rides Callisto's orbital rail for the duration.
http://i135.photobucket.com/albums/q...c/Untitled.jpg
It starts on the 11th in north-central Sagittarius just SE
of the Teaspoon asterism (pocket sky atlas 67).
The unsuspecting 7.9 mag star can be found at ra 19 14 dec -22 34.
SJS