  We demonstrate the simultaneous magneto-optical trapping (MOT) of Rb and Sr
and examine the characteristic loss of Rb in the MOT due to photoionization by
the cooling laser for Sr. The photoionization cross section of Rb in the
$5P_{3/2}$ state at 461 nm is determined to be $1.4(1)\times10^{-17}$ cm$^2$.
It is important to consider this loss rate to realize a sufficiently large
number of trapped Rb atoms to achieve a quantum degenerate mixture of Rb and
Sr.
