This comes down to a combination of 2 things, width & forward distance. Once you have both those numbers, use the graph below to work out which category it's in:

The legal requirements are: Cat 1 A single Class 2 pilot, day or night. Cat2 A single Class 2 Pilot during the day A Class 1 pilot and a Class 2 Pilot at night Cat 3 A Class 1 pilot and a Class 2 Pilot, night or day Cat 4 A Class 1 pilot and a two Class 2 Pilots