The Rathe Librarian is not trackable. This is similar to another named in the zone, Glutch the Heap, who is not trackable (see my comments there). I was standing right on top of it using my level 85 druid with 175 tracking skill, and it did not show up on the tracking list. The Rathe Archivist, who was in the next room, did show up on tracking.
The Rathe Librarian was up and standing at a static golem spawn spot, just before the room that contains The Rathe Archivist. It was standing at approximately /loc 1018, -1025, -108 .
In addition, this NPC does not see through invisibility. I stood inside of it while invisible, to mark down the /loc and to confirm that it was not trackable.
Rondor
Edited, Jul 18th 2009 8:06pm by RondorNorador
Edited, Jul 18th 2009 8:07pm by RondorNorador

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