  We present the discovery a giant low surface-brightness arc, of length
luminous matrix with surface-brightness mu_B < 26.5 mag arcsec^{-2} and a
number of embedded condensations. It is not associated with any giant galaxy in
Coma in particular; neither does it have the properties of a gravitational arc.
We argue that a fast interaction between the nearby barred S0 galaxy IC 4026
and either IC 4041 or RB 110 is the most natural explanation for the origin of
the arc.
