It's a USNS ship operated by the Military Sealift Command (MSC) which is the civil service arm of the Navy that employs merchant mariners on Naval auxilary ships and some ships of a miscellaneous nature. Most MSC ships are owned and manned by the government under the Dept. of the Navy. Some are owned and long term chartered from private shipping concerns, notably a small fleet of tankers carrying refined product. Both sport the blue and gold stack bands regardless of hull color. MSC also operates the more commonly known "white hulls", the USNS Mercy and USNS Comfort-hospital ships both. MSC operates naval auxilary ships-oilers, supply, and ammo-with about one third the manning that the Navy uses on similar ships, thus saving money overall. Until the 1980's, MSC operated ships that the Navy had previously operated. Since then, MSC has received it's own purpose built ships. There's generally three or four MSC ship's assigned to each navy task force, although they generally only steam with the task force only during replenishment and refueling at sea operations. A task force will generally deploy from the US for 6-12 months and then return to the US. The MSC ships tend to stay in the region of the deployment full time, returning to the US for retro-fit or dry-docking occasionally.
I'm not sure of the name of this particular ship but she's similar to the USNS Redstone which is part of MSCLANT. Those ships track various missile and rocket launches from positions at sea and you need a different security clearance to actually know what they're doing than you do to just "drive" them. A lot of what they track is fairly obvious and pedestrian, but then, they don't exactly talk about that part that is not.
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Wm. F. Buckley, Jr.