Thanks, it's great they can pinpoint those lifetime JC coins to those few months prior and your is a beauty.....bit rude where they struck the banker's mark though...
It was part of the coinage of M. Sanquinius, who was one of the III viri monetales in 17 B.C. The comet on the reverse should have a tail (missing on my coin as it is slightly off centre) which makes it even more prominent. Its rare - R2 in RIC 1 - so one doesn't see many examples