The traditional astronomical symbol for (7) Iris, after Gould, B.A. 1852, On the Symbolic Notation of the Asteroids, Astron. J., 2, 80. As the number of asteroids grew, the symbols got more and more complex, leading to the creation of Minor Planet Numbers. This one, a rainbow with a star under it, was, perhaps, the most complex to date, due to the somewhat difficult concentric bands, though (4) Vesta, before the more modern simplification, was pretty difficult as well. Still, (8) Flora and particularly (10) Hygiea would be much worse, and things got worse from there.
No machine-readable source provided. Own work assumed (based on copyright claims).
No machine-readable author provided. Editor at Large assumed (based on copyright claims).