Hermann Kobold discovered IC 3946 = K. 2-8, along with IC 3947 and 3949, on 12 May 1896 with the 18-inch refractor at the Strasbourg Observatory. He noted "F, pS, bM." and measured an accurate micrometric position.

400/500mm - 17.5" (4/21/90): very faint, small, elongated 2:1 WSW-ENE. A mag 14 star is 1.1' NW. Located in AGC 1656 with IC 3949 2.1' NE and IC 3947 1.7' SSE.

Notes by Steve Gottlieb