  We investigate the absolute calibration of the EUV Imaging Spectrometer (EIS)
on Hinode by comparing EIS full-disk mosaics with irradiance observations from
the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory. We also
use ultra-deep (>10^5s) exposures of the quiet corona above the limb combined
with a simple differential emission measure model to establish new effective
area curves that incorporate information from the most recent atomic physics
calculations. We find that changes to the EIS instrument sensitivity are a
complex function of both time and wavelength. We find that the sensitivity is
decaying exponentially with time and that the decay constants vary with
wavelength. The EIS short wavelength channel shows significantly longer decay
times than the long wavelength channel.
