Strange bright light over Vancouver, Canada

On September 12, 2015, in the early hours of the morning, an inhabitant of Vancouver (British Columbia, Canada) has spotted an unidentified light flying over this big city. What is it?

Witness statement:

Woke up at 3am. Looked out my window and saw this massive bright light. At first I thought it may have been a planet, but it soon became apparent it was much too large. 

The objects light was pulsating and hovering above the city. I watched it for half an hour, and it didn't move. I went back to sleep, woke up 2 hours later, and it was gone.