Northbound-in the distance

On May 18 and 19, 2007, Union Pacific operated an excursion from Tacoma, Washington to Everett, Washington, and back. The northbound portion was headed by one loco. (UP 844), the southbound by another (SP X4419). As a photographer, I learned from the northbound leg what not to do on the southbound leg. Still, my success with one of the southbound shots surprised me. Guess which one.