Hi ecoli!
The answer to your question is not so easy. In the ancient numismatic the definition of
obv. and
rev. depends on the technology of minting.
In just a few words, a coin is produced by inserting a piece of metal, called blank (1) between two dies (2a,b). One of the dies is fixed (in a
type of anvil setup), the other is mobile, held by a worker with tongues. With
his other hand the worker (or another worker) applies a hammer blow to the mobile die and the engravings of the dies are transferred in positive to the blank resulting in a coin (3). Another blank is positioned and struck, and so on.
Please look at
https://www.forumancientcoins.com/forvm/Collectors_Resources.htmlunder 'How does a
brockage occur'
The die under the
flan always(?) wears the
obverse depiction, the die above the
flan is always the
reverse. So is the
standard definition for Greek and
Republican coins!
In imperial times it depends on the
face of the emperor.
Obv. is always the
side with the
bust of the emperor. Are there busts on each
side, then the higher valued emperor defines the
obv. But how we can tell from a coin? If you look at your coin you can see that the
side with the helmeted
Athena is arched concave. So it should be due to the definition the upper
side = the
reverse. But if we look at the importance of the depictions, there are no doubts that this is the
obverse not the
rev.!
Regards