Tacitus AE Antoninianus. Serdica.

Obv: IMP C TACITVS INVICTVS AVG, radiate, draped, cuirassed bust right.
Rev: PROVIDEN DEOR, Providentia, holding two standards, standing 
right, facing Sol, holding globe, and raising right hand, standing 
left. 
Star in lower centre.
Mintmark KA dot gamma.

RIC V (1) 197, rated scarce.
Courtesy of Forum Ancient Coins.