APHIS20 USAF E-4B nightwatch out of Wright-Patterson AFB west
This AC is used by the Sec. of Defense
Found this (cap #2) and it's tied to Dynamic Avaition-which has has several Dash 8's out of Manassas, VA pinpoint in the last few months.
See Cap #3 for one example
Dynamic Aviation located in Bridgewater, VA-see cap #4