I got a map last night while mining. I can't remember which kind, but it pointed to Coerthas. To be honest, it was tough to locate the position on the map even knowing which zone it was. The picture was just a generic looking corner. If I didn't know it was Coerthas I could be looking for it for a very long time.

I got 1 steel ingot, 2 mythril enhanced inks, 5 philosophy tomes and 1400 gil. And it was a one man fight.