Tacitus, AE Antoninianus. Serdica. 

IMP CL TACITVS AVG, radiate, draped, cuirassed bust right.
PROVIDEN DEOR, Providentia, standing facing, holding two 
standards facing Sol, standing left, holding globe and
raising right hand.
Mintmark KA dot gamma dot.

Not in RIC. Estiot 2393 var (obv. legend). Very rare.

Contributed by ars-aeterna, March, 2011