International Comet Quarterly

1. Photometric observations of comets in tabulated format, including carefully-made visual and CCD magnitude estimates of comets with proper documentation; as such, the journal serves to make widely available, in one convenient location, observations made by observers worldwide, and also helps to provide the scientific community with a respectable set of visual data from amateur astronomers. [This is to complement the astrometric observations of comets published in the Minor Planet Circulars/Minor Planets and Comets and the IAU Circulars ];
2. General review of recent studies and observations made of comets, including news of discoveries/recoveries;
3. Review and research articles by cometary astronomers on various aspects of cometary research.
4. Other observations of comets, including descriptive information and images/drawings of comets.
5. Other useful information for the comet observer or researcher, including lists, recommendations, book reviews, etc. An ICQ Guide to Observing Comets is planned for release in November 1996 as an aid to both beginning and experienced (amateur and professional) observers of comets.

The ICQ encourages authors to submit articles for publication in the journal; there is a referee system, as with most scientific journals. Actual computer images of comets (either obtained via CCD, or scanned into electronic images from drawings or photographs) may be sent to the ICQ for possible publication, but contact the Editor before sending images (e-mail address below), and read our instructions on sending images. Photometric observations should be contributed as noted below.

The ICQ Archive of Photometric Data on Comets. The ICQ maintains a computer database of photometric observations of comets, which includes all observations published in the printed ICQ plus data extracted from other journals (mostly historical, dating back to the 19th century). Each observation is given on an 80-character (80-byte) ASCII computer record with comet designation; Universal Time (UT) year, month and date (to 0.01 day); magnitude (usually total visual), magnitude method, reference/source for comparison stars, and notes such as application of correction for atmospheric extinction, etc.; instrument type, aperture, and f/-ratio (and magnification, if visual) used for the observation; coma diameter in arcmin, and the coma's degree of condensation (DC); the tail length and position angle (in degrees); the reference indicating where the observation was published; and a 3-letter, 2-digit code for the observer.

Contributors of observations via e-mail should read this instruction sheet for the proper format. Never, ever use keyboard "TABs" when sending data of any sort to another person, because such characters will mess up regular ASCII files! The special codes used in this tabulation for such things as type of instrument, magnitude method, comparison-star reference, and notes are available here in the Keys to Abbreviations used in the ICQ archival tabulation. Information not easily put into tables are published in textual form in each issue of the ICQ as supplemental descriptive data; such information should be contributed separately from the tabulated data, listed by comet and then chronologically by UT date/time.

When a comet is less than 20 or 30 degrees from the observer's true horizon, and he or she is making a total visual magnitude estimate of the comet (which is done via comparison with a de-focussed nearby star whose known magnitude is taken from an appropriate catalogue), the observer needs to appropriately correct his observed value for atmospheric extinction. A standard procedure recommended by the ICQ and published in the July 1992 issue of the ICQ is now available here online.

Having troubles seeing comets because of all the artificial lights? Check out our page on light pollution!

Further information is available via e-mail from icq@cfa.harvard.edu