[nategri]

I don't think it's that ambiguous.

"Megaton" isn't really used anywhere except for explosive yields, where it always means TNT. As far as the 'native unit' astrophysicists will tend to use ergs for events like supernovae.

https://en.wikipedia.org/wiki/Erg

[kstrauser]

I thought it was ambiguous in the context of an article talking about converting mass to energy. Without running the numbers, I couldn't tell if that was a unit of the input mass or the output energy.