[1] George Mason Univ, Dept Phys & Astron, 4400 Univ Dr, Fairfax, VA 22030 USA
[2] US Naval Observ, 3450 Massachusetts Ave NW, Washington, DC 20392 USA
[3] Naval Res Lab, Remote Sensing Div, 4555 Overlook Ave SW, Washington, DC 20375 USA
[4] Space Telescope Sci Inst, AURA ESA, 3700 San Martin Dr, Baltimore, MD 21218 USA