CCD photometry of distant active comets 228P/LINEAR, C/2006 S3 (LONEOS) and 29P/Schwassmann–Wachmann 1

We presentphotometric investigations of three distant active comets, 228P/LINEAR, C/2006 S3 Lowell Observatory Near-Earth-Object Search (LONEOS) and 29P/Schwassmann-Wachmann 1. The data were obtained with the 1-m optical telescope at Lulin Observatory in Taiwan on 2011 February 5 and 6. These comets were observed at heliocentric distances larger than 3 au, all of them appeared to be active. By cometary morphological and photometric studies, the upper limits of the nuclei radii were derived. Also, the surface brightness profiles, Af rho parameters, mass production rates and the coma colours were measured. Finally, we discussed possible driver of activity in comets.