The form of the explosion told them about the nature of the energy discharge.

"We appear to have been caught in a natural energy discharge of some kind."

Unless, of course, they give off a significant energy discharge, and we happen to be looking in the right place at the time.

There is nothing here capable of producing a significant energy discharge.

Whatever they are, these aliens seem able to track energy discharge.

"How long has it been since the energy discharge?"

"Still got that glitch with the energy discharge through the material?"

The two energy discharges were wide of the mark.

If so, their sensor logs may contain evidence of the energy discharge.

"The energy discharge would alert the troops inside the base."