It looks to be real but a little too large for an As, I would think it is a sestertius. Assarii were made of copper and sestertii of brass, so you can probably tell in hand which it is without measuring its diameter.
I think it is this issue, showing Felicitas (Goddess of luck):http://www.wildwinds.com/coins/ric/...RIC_0672.jpg
IMP CAES NER TRAIANO OPTIMO AVG GER DEC P M TR P COS VI P P - draped, laureate bust right
SENATVS POPVLVSQVE ROMANVS (the senate and the people of Rome) // S - C - Felicitas standing left, holding caduceus and cornucopia - this coin is celebrating the good luck of the people of Rome thanks to Felicitas.
S-C stands for SENATVS CONSVLTVM, signifying that the emperor has permission from the senate to mint copper and brass coinage.