Build a `Time` from a TT calendar date.

        Supply the Terrestrial Time (TT) as a proleptic Gregorian
        calendar date:

        >>> t = ts.tt(2014, 1, 18, 1, 35, 37.5)
        >>> t.tt
        2456675.56640625
        >>> t.tt_calendar()
        (2014, 1, 18, 1, 35, 37.5)

def tt(self, year=None, month=1, day=1, hour=0, minute=0, second=0.0,
           jd=None):
        """Build a `Time` from a TT calendar date.

        Supply the Terrestrial Time (TT) as a proleptic Gregorian
        calendar date:

        >>> t = ts.tt(2014, 1, 18, 1, 35, 37.5)
        >>> t.tt
        2456675.56640625
        >>> t.tt_calendar()
        (2014, 1, 18, 1, 35, 37.5)

        """
        if jd is not None:
            tt = jd
        else:
            tt = julian_date(
                _to_array(year), _to_array(month), _to_array(day),
                _to_array(hour), _to_array(minute), _to_array(second),
            )
        tt = _to_array(tt)
        return Time(self, tt)