No New York, that's no blimp. It's a buildings survey, police said Sunday .

Folks in east Midtown who look up in the sky Monday will notice a new phenom: A large balloon floating about 800 feet up in the air, police said.

The height survey, conducted by a private architecture firm, will look at two buildings. The balloon will fly from 7 a.m. to 8:30 p.m. above East 58th Street and Sutton Place. Police said the same firm conducted a survey Sunday from 11 a.m. to 8:15 p.m. over Chrystie and Stanton Streets.