  Cosmic-ray electrons and positrons propagating in the Galaxy produce diffuse
gamma-rays via the inverse Compton (IC) process. The low energy target photon
populations with which the cosmic-rays interact during propagation are produced
by stars, this stellar light being reprocessed by Galactic dust. Detailed
modelling of the Galactic stellar distribution, dust distribution, and
treatment of the absorption and scattering of light is therefore required to
obtain accurate models for the low energy Galactic photon distribution and
spectrum. Using a realistic Galactic stellar distribution model, and dust
distribution, we calculate the diffuse radiation field from stars in the Galaxy
(the `optical' radiation field), including absorption and scattering. Using a
dust heating code, we self-consistently calculate the infra-red radiation field
for the same dust model used for the optical calculation; both transient and
equilibrium heating are included. We present the calculated radiation field
spectra and distributions, and will use these to calculate the expected
Galactic diffuse IC gamma-ray spectrum.
