The Listening Post can be found in the Synuefe XE-Y c17-7 system, around body 3 a. The location matches the description found in the flight of the Adamastor, so it is believed that the Listening Post is related.
It was found by following a path from Chukchan through HIP 39748 and HIP 33386 and travelling for around 370 Ly then looking for a K class star with 11 bodies. It is believed that the Listening Post will probably point to Site 23B.
Message:
DATA DOWNLOAD
8BFGTY4PLU67-RTYO06.45:GN63-74PHGJI E67-:F563-21-574.9 ER34.6-DER8+WEST U.5 -RTG10 RTH8-4 6T.WR4564-21 +G134.2 RT55.4 GDW THE42.1LY 764.2Y-45TG4.BTJ-Y. 6ORT437.1D341-67.Y5DS 243 45TY-3234
Note that the message has been found to be slightly different in various localisations – notably in French the ‘WEST’ text is ‘OUEST’.
The message has been at least partially decoded by MichaelWhatever on the forums – splitting it into 8 character lines you can see the text ‘615 LY’ (the distance to the Coal Sack system) and BODY 3 embedded in the text.