The ultraviolet polarization of the Crab pulsar

The linear polarization of the Crab pulsar has been observed in the ultraviolet using the High Speed Photometer on the Hubble Space Telescope. The polarization as a function of pulse phase is strikingly similar to that observed in the visible, with the same values of fractional polarization and the same swing of position angle occurring through the main and secondary pulses, The polarization pulse profile must be essentially wavelength-independent at wave-lengths shorter than the infrared, as predicted by the geometric model of the emission region proposed by Smith et al.