  In Raman (2007), using a column construction technique it is proved that
every interval graph can be colored online with First Fit with at most $8w(G)$
colors, where $w(G)$ is the size of the maximum clique of $G$. Since the column
construction can not be adapted to circular arc graphs we give a different
proof to establish an upper bound of $9w(G)$ for online coloring a circular arc
graph $G$ with the First Fit algorithm.
