Neutron star concluded that the radiation comes from a neutron star at the stage of accretion. In 1967, Jocelyn Bell Burnell and Antony Hewish discovered regular radio pulses from PSR B1919+21. This pulsar was later interpreted as an isolated, rotating neutron star. The energy source of the pulsar is the rotational energy of the neutron star. The majority of known neutron stars (about 2000, as of 2010) have been discovered as pulsars, emitting regular radio pulses. In 1971, Riccardo Giacconi, Herbert Gursky, Ed Kellogg, R. Levinson, E. Schreier, and H. Tananbaum discovered 4.8 second pulsations in an X-ray source in the constellation
Neutron star towards the plane of curvature. In addition, high energy photons can interact with lower energy photons and the magnetic field for electron-positron pair production, which through electron–positron annihilation leads to further high energy photons. The radiation emanating from the magnetic poles of neutron stars can be described as "magnetospheric radiation", in reference to the magnetosphere of the neutron star. It is not to be confused with "magnetic dipole radiation", which is emitted because the magnetic axis is not aligned with the rotational axis, with a radiation frequency the same as the neutron star's rotational frequency. If the axis of rotation