  Outside a black hole, perturbation fields die off in time as $1/t^n$. For
spherical holes $n=2\ell+3$ where $\ell$ is the multipole index. In the
nonspherical Kerr spacetime there is no coordinate-independent meaning of
"multipole," and a common sense viewpoint is to set $\ell$ to the lowest
radiatiable index, although theoretical studies have led to very different
claims. Numerical results, to date, have been controversial. Here we show that
expansion for small Kerr spin parameter $a$ leads to very definite numerical
results confirming previous theoretical analyses.
