Revised Wavelength and Spectral Response Calibrations for AKARI
  Near-Infrared Grism Spectroscopy: Post-Cryogenic Phase
  We present a new calibration for the second-order light contamination in the
near-infrared grism spectroscopy with the Infrared Camera aboard AKARI,
specifically for the post-cryogenic phase of the satellite (Phase 3). Following
our previous work on the cryogenic phase (Phases 1 and 2), the wavelength and
spectral response calibrations were revised. Unlike Phases 1 and 2, during
Phase 3, the temperature of the instrument was not stable and gradually
increased from 40 to 47 K. To assess the effect of the temperature increase, we
divided Phase 3 into three sub-phases and performed the calibrations
separately. As in Phases 1 and 2, we confirmed that there was contamination due
to the wavelength dependence of the refractive index of the grism material in
every sub-phase. The wavelength calibration curves for the three sub-phases
coincided with each other and did not show any significant temperature
dependence. The response decreased with temperature by ~10% from the beginning
to the end of Phase 3. We approximated the temperature dependence of the
response as a linear relation and derived a correction factor as a function of
temperature. The relative fraction of the second-order light contamination to
the first-order light was found to be by 25% smaller than in Phases 1 and 2.
