The CMB bispectrum from recombination
  We compute the cosmic microwave background temperature bispectrum generated
by nonlinearities at recombination on all scales. We use CosmoLib$2^{\rm nd}$,
a numerical Boltzmann code at second-order to compute CMB bispectra on the full
sky. We consistently include all effects except gravitational lensing, which
can be added to our result using standard methods. The bispectrum is peaked on
squeezed triangles and agrees with the analytic approximation in the squeezed
limit at the few per cent level for all the scales where this is applicable. On
smaller scales, we recover previous results on perturbed recombination. For
cosmic-variance limited data to $l_{\rm max} =2000$, its signal-to-noise is
$S/N=0.47$ and will bias a local signal by $f_{\rm NL}^{\rm loc}\simeq 0.82$.
