Bodies in the outer Solar System may consist of, or be covered by, solid ammonia. Their temperature depends on its emissivity. We calculate that emissivity as a function of frequency, angle and polarization and convolve it with a Planck function to obtain its integrated emissivity.
@article{arxiv.1903.04960,
title = {Emissivity of Ammonia Ice},
author = {S. Wang and J. I. Katz},
journal= {arXiv preprint arXiv:1903.04960},
year = {2019}
}