The calculation formula of speed is speed = distance ÷ time, so the distance and time are calculated separately.
Distance is the short arc mentioned above, and the calculation formula is distance = radius × radian.
So s = r× 1.0× 10-6 rad = 5000 (light years) ×(365×24×60×60)×(3× 10? 8 (light speed) × 1.0× 10-6 rads
Time t=365×24×60×60.
So the speed v=s÷t=5000 (light years) ×(3× 10? 8 (light speed) × 1.0× 10-6 rad = 1500 km per second.
As for the explosion time, it is very simple that 1054-5000 is 3946 BC.