  LOPES was a digital antenna array detecting the radio emission of cosmic-ray
air showers. The calibration of the absolute amplitude scale of the
measurements was done using an external, commercial reference source, which
emits a frequency comb with defined amplitudes. Recently, we obtained improved
reference values by the manufacturer of the reference source, which
significantly changed the absolute calibration of LOPES. We reanalyzed
previously published LOPES measurements, studying the impact of the changed
calibration. The main effect is an overall decrease of the LOPES amplitude
scale by a factor of $2.6 \pm 0.2$, affecting all previously published values
for measurements of the electric-field strength. This results in a major change
in the conclusion of the paper 'Comparing LOPES measurements of air-shower
radio emission with REAS 3.11 and CoREAS simulations' published in
Astroparticle Physics 50-52 (2013) 76-91: With the revised calibration, LOPES
measurements now are compatible with CoREAS simulations, but in tension with
REAS 3.11 simulations. Since CoREAS is the latest version of the simulation
code incorporating the current state of knowledge on the radio emission of air
showers, this new result indicates that the absolute amplitude prediction of
current simulations now is in agreement with experimental data.
