If Oothiana went looking for him and discovered his absence, then the chase would be on at once.

Then it was that we discovered his absence and feared the worst.

The Romulans will discover our absence in a very short while.

Sooner or later the mercenaries were going to discover their absence.

The minstrels would be discovering his absence any moment now.

So potentially, it could have been missing for three days before you discovered its absence.

He could do that only by getting back to the dance before Helene discovered his absence.

It is too easy to get distracted and suddenly discover its absence.

I could tell he had written it before he discovered my absence.

Discovering her absence, the others must have backtracked to the stone bridge.