Dust Reradiation from NGC 6946

Far infrared measurements of dust reradiation for the spiral galaxy NGC 6946 are presented. The measurements consist of maps and an energy distribution, all made with a resolution of 49 sec. Effective wavelengths are 120 and 170 microns for the maps and 60, 120, and 170 microns for the energy distribution. Much of the reradiating dust has a temperature of 20 K. The amount of starlight reradiated at far infrared wavelengths is approx. 6 x 10 to the 10th power L(solar) or about half the total amount of starlight produced by the nucleus and disk of NGC 6946. A bright nuclear peak centered on a 5' wide disk describes the reradiation morphology at 170 microns. The disk contributes approx. 90% of the total reradiation; the 49 sec diameter region centered on the nucleus gives the small remainder. The morphology of reradiated starlight is compared to the familiar starlight morphology observed at optical wavelengths.