Short-term variability of comet C/2012 S1 (ISON) at 4.8 AU from the Sun

摘要

Context. We observed comet C/2012 S1 (ISON) during six nights in February 2013 when it was at 4.8 AU from the Sun. At this distance and time the comet was not very active and it was theoretically possible to detect photometric variations likely due to the rotation of the cometary nucleus.