This is a cylindrical projection of the yield of cosmic ray albedo protons from the Moon. Colors represent the "yield," or ratio of lunar protons to GCR protons, from red (.42) to blue/purple (.38). The spatial resolution is 15 degrees. The uncertainty of the yield for each pixel is 0.015, or about 38% of the total range of values. Clusters of high-yield pixels (e.g., longitude 30, latitude +15) are a more statistically significant indication of local yield enhancements than individual bright pixels.
The "yield" is the number of upward-propagating albedo protons from the Moon divided by the number of downward-propagating cosmic ray protons. In this case, low energy, high LET (linear energy transfer) cosmic ray protons were selected to represent the temporal variability of the entire GCR spectrum.
This map includes the first 19 months of CRaTER data from the LRO mission: July 2009 through early January 2011, a period with a remarkably low level of solar particle activity. The first large solar particle event of solar cycle 24 occurred on January 27, 2011.
Publication: The first cosmic ray albedo proton map of the Moon (2012), Jody K Wilson, Harlan E Spence, Justin Kasper, Michael Golightly, J Bern Blake, Joe E Mazur, Lawrence W Townsend, Anthony W Case, Mark Dixon Looper, Cary Zeitlin, Nathan A Schwadron, Journal of Geophysical Research: Planets, 117, E00H23.