USS footprint in equatorial coordinates using an Aitoff projection. The blue circles are the USS DR1 fields. The purple circles are the observed fields, and the gold ring indicates the fields in the region of the Galactic disk. The gray circles indicate the footprint area not observed yet. The background represents E(B – V) values ranging from 0.0 (white) to 0.5 (black) according to the map by Schlegel et al. (1998).