comets.dat is an ASCII file of cometary orbital elements prepared at the "Institut de Mecanique Celeste et de Calcul des Ephemerides" (related to the Bureau des Longitudes, Paris). The research and computing needed to generate comets.dat are funded by the French Ministry of Education. The data can be freely used, provided that their origin (Bureau des longitudes) and the author (P. Rocher) are properly cited. User feed-back is encouraged. Unless otherwise specified, send comments and bug reports to: E-mail : stc@imcce.fr Fax : (33) 1 46 33 28 34 Postal mail : IMCCE - Observatoire de Paris 77 avenue Denfert Rochereau F-75014 PARIS