An unidentified HEO object
One of the four images capturing the latter, contained an unknown object some 3 degrees south of USA 198. It is a clear trail, similar to that of USA 198 in length and direction. It shows evidence of being the capture of a brief flare. And it doesn't match any known object from the unclassified or classified catalogues.
Below is a detail of the image showing the object (the inset is a 200% blow-up). The trail is about 20 pixels long, or about 3.5'.