Published online by Cambridge University Press: 12 April 2016
Optical spectroscopy on nearly 50 filaments of 3C58 indicates a maximum expansion velocity of 1100 ± 100 km s−1. A considerable range in radial velocity with projected distance from remnant center is found suggesting that the remnant’s optical emission is not confined to a thin shell. Typical filament electron densities are between 200 - 500 cm−3 with Hα/[N II] ratios in the range 0.2 - 0.5. Optical extinction to 3C58 is modest with E[B-V] = 0.68±0.08. Preliminary radial proper motion measurements for a few outlying filaments suggest values of order 0.05” - 0.07” yr−1.