Reposted from https://blogs.nasa.gov/mission-ames/2013/05/23/post_1369289647791/.

We got the “go” to proceed with line ops. SOFIA, a 747SP,was towed out of its hangar onto a side-runway, and away from any air traffic. The heading is 130.5. This is important as it tells us what view angles are available from the telescope. The telescope looks out the aft-port side of the aircraft. (Aft=back of wing, Port=left side, when viewed from the back, facing the front). So at this heading, we are looking at the N-E portion of the sky. Our calibration targets include TDra, NSV25184, RUCyg, muCep, and TCass, all pretty bright stars.

We walked out from the hangar to the craft and can come/go from the craft during the night. Of course, this is not what will be like during the flight. Below is a picture of our ingress/egress path on the plane,

A “true stairway to the stars.”  I learned that for the flights, we would do a similar activity, meaning we do not board within the hangar, but board after the craft has been towed out to the runway.