Abukar is a loremaster and astronomer living in Maadoran Merchants Plaza district.
You see a bald, bearded man fiddling with an old telescope, bearing signs of crude repair. “If you want me to do a chart, you’re wasting your time,” says the man, his accent thick and heavy.
On top of tower, north-west of Maadoran Merchants Plaza
Abukar mentions that he made a device to navigate on The Abyss and you can persuade him to trade it with you if you offer an artifact of equal value.
However, this content has not been implemented by the game developers. 
Access to Library of Saross
- https://steamcommunity.com/app/230070/discussions/0/541906348058363111/ Abukar's Device (2015)