Frost lines and footings
 

Here in NWNJ my frost line is 36". I'm considering pouring a pier for my telescope but 3 feet is alot of digging. I'm wondering would a spread footing one foot down measuring 1 x 1 x .5 feet be stable enough to avoid freeze thaw shifting.

The load would be approx 200 lbs. on the pier.

thoughts?

Frostline is only a concern for heaving. If you're worried about the slab moving, rent a powered posthole auger, bore four six inch holes with rebar that extends above the holes, pour, then pour a slab over the four pillars. Me, I'd pour a 6" thick slab and call it a day if you're not worried about the slab moving during the winter.