A polarization study of the supernova remnant CTB 80
  We present a radio polarization study of the supernova remnant CTB 80 based
on images at 1420 MHz from the Canadian Galactic plane survey, at 2695 MHz from
the Effelsberg survey of the Galactic plane, and at 4800 MHz from the
Sino-German 6cm polarization survey of the Galactic plane. We obtained a
rotation measure (RM) map using polarization angles at 2695 MHz and 4800 MHz as
the polarization percentages are similar at these two frequencies. RM exhibits
a transition from positive values to negative values along one of the shells
hosting the pulsar PSR B1951+32 and its pulsar wind nebula. The reason for the
change of sign remains unclear. We identified a partial shell structure, which
is bright in polarized intensity but weak in total intensity. This structure
could be part of CTB 80 or part of a new supernova remnant unrelated to CTB 80.
