C2 imagery of the inner coma of Comet IRAS-Araki-Alcock

May 10, 1983 observations of the comet IRAS-Araki-Alcock are analyzed to determine the spatial molecular abundance of C2 in the inner coma, via the Delta-v = +1 Swan band sequence near 4690 A. The observations indicate a deficiency of C2 emission across a projected diameter of about 2000 km that is centered on the peak of continuum emission. Comet imagery indicates a sunward-pointing coma that suggests an outburst of subsurface volatile ices through a nonvolatile surface crust, as predicted for periodic comets. These results are discussed in the framework of instrumental and observational constraints.