A powerful extended source of infrared radiation behind the Orion Nebula, discovered in 1967 by the American astronomers Douglas Erwin Kleinmann (1942– ) and Frank James Low (1933–2009). The total luminosity is 100 000 times that of the Sun. The KL region consists of a cluster of infrared sources, presumably young stars, of which the most powerful is designated IRc2. The source of high-velocity outflows from the region lies close to IRc2.