  Spiral density wave theories demand that grand design spiral structure be
bounded, at most, between the inner and outer Lindblad resonances of the spiral
pattern. The corotation resonance lies between the outer and inner Lindblad
resonances. The locations of the resonances are at radii whose ratios to each
other are rather independent of the shape of the rotation curve. The measured
ratio of outer to inner extent of spiral structure for a given spiral galaxy
can be compared to the standard ratio of corotation to inner Lindblad resonance
radius. In the case that the measured ratio far exceeds the standard ratio, it
is likely that the corotation resonance is within the bright optical disk.
Studying such galaxies can teach us how the action of resonances sculpts the
appearance of spiral disks. This paper reports observations of 140 disk
galaxies, leading to resonance ratio tests for 109 qualified spirals. It lists
candidates that have a good chance of having the corotation resonance radius
within the bright optical disk.
