  At densities between 10^8 and 10^10} g/cm^3 electron capture in a
presupernova collapse is believed to mainly occur on odd-odd nuclei. We have
derived the rates for six of the most important electron capturing nuclei,
{54,56,58}Mn and {56,58,60}Co, based on calculations of the Gamow-Teller
strength distributions for the ground states and first excited states. These
calculations have been performed by shell model diagonalization in the pf shell
using a recently modified version of the KB3 interaction. The shell model rates
are noticeably smaller than the presently adopted rates as the latter have been
derived by placing the Gamow-Teller (GT) resonance at too low excitation
energies.
