"The scientists pinpointed the outburst to a magnetar known as SGR 1935+2154, located about 30,000 light-years from Earth towards the galaxy's center in the constellation Vulpecula. This is the closest known FRB to date.
"We were able to determine that the energy of this burst is comparable to the energies of extragalactic fast radio bursts," Bochanek added. "In about 1 millisecond, the magnetar emitted as much energy in radio waves as the sun does in 30 seconds."
All in all, "we were able to determine the rate of these bright bursts from magnetars is consistent with the known rate of extragalactic fast radio bursts," Bochenek said. "This discovery therefore paints the picture that some, and perhaps most, fast radio bursts from other galaxies also originate from magnetars."
Very good observation and find here. Neutron star mean densities ~ 10^14 - 10^15 g cm^-3.