After this time remove the fat (keept it!) from the tray and pour 1 glas of water into it. Let the bird roast for another 45-50minutes and repeat the process another 2 times. Keep the fat with juice in the freezer.
(The tray in the oven will contain fat only when you remove it after first 45minutes of roasting. The next two times the goose will give up the juices as well)