src/Marando/AstroDate/AstroDate.php
public function toTDB()
    {
        if ($this->timescale == TimeScale::TDB()) {
            return $this;
        }

        $this->toTT();
        $tt1 = $this->jd;
        $tt2 = $this->dayFrac;

        $this->toUT1();
        $ut = $this->dayFrac;

        $dtr = IAU::Dtdb($tt1, $tt2, $ut, 0, 0, 0);
        IAU::Tttdb($tt1, $tt2, $dtr, $tdb1, $tdb2);

        $this->jd        = $tdb1;
        $this->dayFrac   = $tdb2;
        $this->timescale = TimeScale::TDB();

        return $this;
    }
public function toTDB()
    {
        if ($this->timescale == TimeScale::TDB()) {
            return $this;
        }

        $this->toTT();
        $tt1 = $this->jd;
        $tt2 = $this->dayFrac;

        $this->toUT1();
        $ut = $this->dayFrac;

        $dtr = IAU::Dtdb($tt1, $tt2, $ut, 0, 0, 0);
        IAU::Tttdb($tt1, $tt2, $dtr, $tdb1, $tdb2);

        $this->jd        = $tdb1;
        $this->dayFrac   = $tdb2;
        $this->timescale = TimeScale::TDB();

        return $this;
    }
Converts this instance to Barycentric Dynamic Time (TDB)

@return static