A gamma-ray telescope intercepts a pulse of gamma radiation from the magnetar, a sort of star having a spectacularly big magnetic field. The pulse lasts 0.30 s and delivers 8.8 x 10-6 J of energy perpendicularly to the 56-m2 surface area of the detector of telescope. The magnetar is thought to be 5.74 x 1020 m (around 61000 light-years) from earth, and to encompass a radius of 8.8 x 103 m. Determine the magnitude of the rms magnetic field of the gamma-ray pulse at the surface of magnetar, supposing that the pulse radiates uniformly outward in all the directions. (Suppose a year is 365.25 days.)