The Custer Institute and Observatory located on Long Island’s north fork, in the town of Southold is Long Island’s oldest public observatory. The Observatory was established in 1927 and is currently run by a staff of dedicated volunteers.
Inside the dome is a 25 inch, f/5 Obsession Newtonian-style reflecting telescope standing 11 feet tall. Outside are several smaller domes that the staff will assist you with as you try to see all that the heavens have to offer.
Currently the observatory is open on Saturday nights. The institute is run completely on donations and a $5 donation gets you a look at the stars from inside the big dome.