  We study the properties of charmonium states at finite temperature in
quenched QCD on isotropic lattices. We measured charmonium correlators using
non-perturbatively $\cO(a)$ improved clover fermions on fine ($a=0.01$ fm)
lattices with a relatively large size of $128^{3}\times 96$, $128^3\times48$,
$128^3\times32$ and $128^3\times24$ at $0.73~T_c$, $1.46~T_c$, $2.20~T_c$ and
$2.93~T_c$, respectively. Our analysis suggests that $\Jpsi$ is melted already
at $1.46~T_c$ and $\eta_c$ starts to dissolve at $1.46~T_c$ and does not exist
at higher temperatures. We also identify the heavy quark transport contribution
at the spectral function level for the first time.
