Achieving the background limit on SOFIA: a stray-light issue

This paper will summarize the stray-light study commissioned by USRA from BRO (Breault Research Organization) to estimate the level of dynamic background that might be observable at SOFIA's focal plane. This dynamic background is due to cavity and aircraft motions with respect to the inertially fixed telescope. BRO used their ASAP program to trace rays emitted from the Earth, aircraft engines, and telescope cavity to the focal plane through reflection and scatter off a number of surfaces (including Level 500 contaminated optics).