Thanks.  Ah, here it is, I got the name slightly wrong:
http://wiki.travellerrpg.com/Disappearance_on_Aramat

This module is set in the Precipice subsector "one half sector coreward from
the Imperial border". However no indication is given as to which sector it
is located with in, but according to the data it should be near one of the
rifts.

Frank