CCD photometry of distant comets

While it is apparent that many comets are active beyond the canonical dista nce of 3 AU, few surveys of cometary activity have been performed in this r egion previously. Such a survey enables a more accurate determination of th e proportion of comets that exhibit little or no outgassing at these distan ces. Results are presented of CCD observations of comets in the region of 3 AU less than or equal to R-h less than or equal to 6 AU obtained with the Im JKT on La Palma. Photometric observations of 15 comets were obtained, 7 of which displayed coma activity and 8 of which appeared inactive. BVR phot ometry was performed on these comets to determine dimensions, colours and o utgassing rates. Although 40P/Vaisala I and 26P/Grigg-Skjellerup were not d etected, upper limits to their nuclear radii are presented. The results obt ained are compared with previous observations.