DECam + Atmosphere transmission functions from Y3A2, and used
in the DES-SN3YR analysis of cosmological parameters.

No out-of-band transmission.

For SNANA analyses, the	calibration files (KCOR_FILE argument)
are located here,
      $SNDATA_ROOT/kcor/DES/DES-SN3YR/LOWZ
      $SNDATA_ROOT/kcor/DES/DES-SN3YR/DECam