Hubble refers to the iconic Hubble Space Telescope, but in aerospace circles, it is also used as a shorthand for any large, bus-sized optical satellite featuring a massive primary mirror. Many classified reconnaissance satellites share the same fundamental chassis and optical design as Hubble, just pointed down at Earth instead of out into deep space.
Heard on the job
The new spy bird they're launching out of Vandenberg is basically a Hubble pointing at the ground.