@eteq - yes, it is that I would write LST as `hh:mm:ss` myself and I think it indeed implies we should be able to have this output method generally for time-like quantities.

This PR should not have to wait for that, however, so I'd say to just decide either way (make it return a Quantity or keep it an Angle), and then raise an issue that reminds us of work to be done. My slight tendency for keeping it an Angle for now is that LST is perhaps most logically a `TimeDelta`, in which case there is little sense in moving it to another class first. But I think it doesn't matter too much; perhaps just let @taldcroft take his pick?