Predicted favorable visibility conditions for anomalous tails of comets

Visibility conditions are used to list the comets that have displayed a sunward dust tail during the time of earth's passage through the orbital plane of the comet. A computer program describing the conditions for this type of antitail observability was applied to the Catalogue of Cometary Orbits (Marsden, 1975), starting with the comets of 1737. It is shown that only about 20-30% of the nearly parabolic comets that should have displayed an antitail at the node were actually observed to do so. There appears to be a general absence of antitails among the short period comets.