Hard to see.
Why?
How can you do it?
HST (Bahcall, others)
Near Infrared (eg., McLeod et al. 1996)
AO
sort of.
Issues here.
What are their properties? Are they related in any way to the activity?
Very little known before advent of HST, AO, and large near-IR detectors.
Still a challenging type of observation.
Initially thought (based on Seyfert galaxies and radio galaxies) that radio properties were related to host
type. Seems to have been a selection effect.