Published online by Cambridge University Press: 14 May 2014
We study the automorphic Green function $\mathop{\rm gr}\nolimits _\Gamma $ on quotients of the hyperbolic plane by cofinite Fuchsian groups
$\Gamma $, and the canonical Green function
$\mathop{\rm gr}\nolimits ^{\rm can}_X$ on the standard compactification
$X$ of such a quotient. We use a limiting procedure, starting from the resolvent kernel, and lattice point estimates for the action of
$\Gamma $ on the hyperbolic plane to prove an “approximate spectral representation” for
$\mathop{\rm gr}\nolimits _\Gamma $. Combining this with bounds on Maaß forms and Eisenstein series for
$\Gamma $, we prove explicit bounds on
$\mathop{\rm gr}\nolimits _\Gamma $. From these results on
$\mathop{\rm gr}\nolimits _\Gamma $ and new explicit bounds on the canonical
$(1,1)$-form of
$X$, we deduce explicit bounds on
$\mathop{\rm gr}\nolimits ^{\rm can}_X$.