Importing Gigapixel Still Image for Use in Premier Pro

As a relative newcomer to Premiere Pro having been a Sony Vegas user for years I am attempting to do a 4K video tour of a very large photo that measures 48533 x 19421 pixels. This photo is a stitched gigapixel image I shoot in Alaska.

Sony Vegas allows me to import the image and put it on the time line. I then set the length of the image to say 2 minutes. Using Keyframes, I then pan, tilt & zoom to create a video tour of the image. The problem I am having in Vegas is the rendered video is not smooth. As I do a pan or zoom it jumps for point to point which is very unpleasing.

I want to use Premiere to try a similar approach to see if it can render the video with not jumps or jerks in the final video. Howver, Premiere will not import the image at all. It gives an error stating that the "File video dimensions (width, height) too large". So, apparently there is some upper limit in Premiere related to still image size.

My questions are: What is that upper limit? Is there any way to get past that limit using After Effects or some other application?