Pretty much all telescopes (under computer/time control) on this planet rely on UTC being quite close to UT1, since every second difference leads to a 15 arcsecond error in the pointing of the telescope (error between where you want to point the telescope on the sky and where you are actually pointing).
While <5s is usually not a problem (except for some instruments with very very small FoV), at 30s it really becomes a problem for instruments with modest fields of view.
