PSR B0628-28 is a radio pulsar which was first detected in the X-ray band by ROSAT and then later observed with Chandra and XMM- Newton .
The Chandra observation yielded an X-ray luminosity two orders of magnitude higher than what is expected for spin-powered pulsars , also there were no pulsations detected .
The XMM- Newton observation , however , reveals pulsations at the expected radio period , P = 1.244 s. The simultaneously analyzed spectra also give a luminosity ( in cgs ) \log { L _ { \mbox { x } } } = 30.34 , which is \sim 350 times greater than what would be expected from the correlation between L _ { \mbox { x } } - \dot { E } .