  We present evidence, based on Chandra ACIS-S observations of the nearby
spiral galaxy NGC 6946, that the extraodinary X-ray luminosity of the MF 16
supernova remnant actually arises in a black-hole X-ray binary. This conclusion
is drawn from the point-like nature of the X-ray source, its X-ray spectrum
closely resembling the spectrum of other ultraluminous X-ray sources thought to
be black-hole X-ray binary systems, and the detection of rapid hard X-ray
variability from the source. We briefly discuss the nature of the hard X-ray
variability, and the origin of the extreme radio and optical luminosity of MF
16 in light of this identification.
