First results from the longitudinally polarized frozen-spin target (FROST)
program are reported. The double-polarization observable E, for the reaction
$\vec \gamma \vec p \to \pi^+n$, has been measured using a circularly polarized
tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions
were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the
Thomas Jefferson National Accelerator Facility. These polarization data agree
fairly well with previous partial-wave analyses at low photon energies. Over
much of the covered energy range, however, significant deviations are observed,
particularly in the high-energy region where high-L multipoles contribute. The
data have been included in new multipole analyses resulting in updated nucleon
resonance parameters. We report updated fits from the Bonn-Gatchina, J\"ulich,
and SAID groups.
