Impact of leap second insertion in UTC on astronomy and the discussion in the IAU working group on the redefinition of UTC

The International Astronomical Union (IAU) is the international organization of researchers in the field of astronomy; this community has deep and strong relations with the international timescale. Extensive studies and discussions on a possible redefinition of the UTC were carried on in the IAU working group on the redefinition of UTC. We will show the recent discussion on the impact of leap second in UTC on astronomy and the activities of the IAU working group.