How to query the Fireteam Finder for a specific dungeon?

[clau100]

I would like to make an app that gives me a notification whenever someone makes a post for Shattered Throne or for Pit of Heresy. How would I go about that? Is it using the Fireteam/Search/Available endpoint?
I tried querying for activity id = 82, as that was dungeons in the docs, but the results were empty.