The Ptolemy Station was created by Sovereign Colonies to trace the Master Signal of the Markers.
Not much is known about it's structure, but it appears that in the topmost of the station research was conducted, while the lower part stored Marker Pylons, which were used to trace the source of the Master Signal.
It's unknown when the station was created, but it can be assumed that it was at least a couple of years before the Tau Volantis Expedition. It's also unknown how long the research lasted, but once it was completed, Sovereign Colonies command commissioned the Expedition.
It was abandoned sometime later, presumably when the station was of no use to the war effort or when the Sovereign Colonies lost the war.
In 2514, Ellie Langford, Robert Norton and John Carver, along with a group of soldiers under Norton, traveled there to extract information about the Master Signal and locate ''the source'' of Markers, using Marker Pylons. Afterwards, the station was destroyed by USM Eudora's armaments, so that The Circle could not extract any information from it.