This document discusses tracking a mobile target using a navigated mobile sensor in a wireless sensor network. It proposes using time of arrival measurements from both the target and sensor to estimate their locations and direct the sensor's movement. A min-max approximation approach is used to estimate locations, which is solved using semidefinite programming relaxation. A cubic function navigates the mobile sensor, and a weighted tracking algorithm further improves performance by making more efficient use of measurement information. Evaluation shows the algorithm provides good target tracking and quickly directs the mobile sensor to follow the target.