We present an updated cumulative size distribution ( CSD ) for Jupiter Family comet ( JFC ) nuclei , including a rigourous assessment of the uncertainty on the slope of the CSD .
The CSD is expressed as a power law , N ( > r _ { N } ) \propto r _ { N } ^ { - q } , where r _ { N } is the radius of the nuclei and q is the slope .
We include a large number of optical observations published by ourselves and others since the comprehensive review in the Comets II book ( ) , and make use of an improved fitting method .
We assess the uncertainty on the CSD due to all of the unknowns and uncertainties involved ( photometric uncertainty , assumed phase function , albedo and shape of the nucleus ) by means of Monte Carlo simulations .
In order to do this we also briefly review the current measurements of these parameters for JFCs .
Our final CSD has a slope q = 1.92 \pm 0.20 for nuclei with radius r _ { N } \geq 1.25 km .