ICQ
The ICQ publishes an annual Comet Handbook several months before the start of the year that the Handbook represents. (Thus, the 1998 Comet Handbook was published in June 1997; the 1999 Comet Handbook was published in August 1998; the 2003 Comet Handbook was published in December 2002; etc.) The Comet Handbook lists orbital elements and ephemerides (for both equinoxes B1950.0 and J2000.0) for both long- and short-period comets predicted to be brighter than magnitude 21-22 during the given year. This Comet Handbook is unique in being probably the only printed book containing (at the time of publication) the best orbital elements, 'perturbed' ephemerides, and magnitude parameters (brightness predictions) for all comets predicted to be brighter than mag 21-22 during that given year (and including also ephemerides for other comets of interest, including 1P/Halley and comets slated for future spacecraft visits). But since the Comet Handbook will contain no comets discovered after the time of issue, one should consult the IAU Circulars or the Minor Planet Circulars (and these web pages) for more up-to-date information. For further information on purchasing the Comet Handbook, click here.