Department of the 20th century art metropolitan museum of art ??

Is this just a copy???

The information below is the printing at the bottom and the size is 42.75"x27 would this be a lithograph, print or a poster and is there a difference?
Any information would be GREAT...

Department of the 20th century art metropolitan museum of art

ALPHA-PI. Acrylic on canvas, 1960, by Morris Louis, American (1912-1962). Arthur

Hoppock Hearn Fund (67.232)

02-02283-8