Spring Season Approximation for Earth's Solar-band Radiance at the Moon, Revised

It accompanies the manuscript "Earthshine as an Illumination Source at the Moon" by Glenar et al., submitted to Icarus on 2/27/2018, and revised 9/10/2018 . It presents a simple formulation for approximating Earth's spectral radiance at the Moon, as a function of: 1.

Earth's phase angle 2. sub-observer position, i.e. Earth's longitude and latitude from the perspective of a lunar observer, and 3. wavelength This approximation was computed by fitting to a grid of NASA Virtual Planetary Laboratory (VPL) models covering Mar-April 2008. Wavelength coverage is 0.30 to 2.5 microns. The approximation is valid for sub-observer latitudes between 30S and 30N (i.e. from a lunar perspective), and Earth orbital phase angles less than 60 degrees.