Measurements of the linear polarization of 3C 345, an OVV quasar with superluminal motion, were obtained with the High Speed Photometer aboard the Hubble Spae Telescope in two UV bandpasses on April 6-7 1993. These measurements are compared with ground-based optical measurements taken 11 days following the HSP observations. The polarization, which decreases with increasing frequency from the I to U bandpasses, reverses this trend and increases in the UV. If the two observation sets represent the same state of spectral polarization, then either the polarization of the synchrotron continuum must increase significalntly in the UV, or there is a second source of polarized flux in 3C 345 in the ultraviolet.
Thursday program listing