Testing out a new telescope camera, chance encountered a bird catching a ride on a thermal.
Bravo! Delighted to see you putting some trigonometry and 'rithmetic to good use in an unusual way. Good example for youngsters who may not see the value of learning such things when there's an Internet.
By the way, the shape of the bird's wings and tail is consistent with an eagle or hawk, so your 1.5-2 meter working assumption seems right on.