Faint comet searching

Comets are usually discovered to a magnitude limit of about 19 at best. This can be improved by one magnitude with a blink-search technique that is described here. To find a new comet, the required search area near opposition is about 600 square degrees at a magnitude limit of about 20.0. Three faint comets were found this way; they are inconspicuous and would not have been discovered in any other manner. It therefore appears that the presently known statistics must be incomplete at the faint end due to incompleteness of the discovery observations. Another future method to find such inconspicuous comets is with electronically scanning cameras and computerized reduction. If such a CCD scannerscope were to have an aperture of about 1.8 m, it could discover at least 40 comets per year.