public static function Apcg($date1, $date2, array $ebpv, array $ehp,
          iauASTROM &$astrom) {

    /* Geocentric observer */
    $pv = [ [ 0.0, 0.0, 0.0],
        [ 0.0, 0.0, 0.0]];

    /* Compute the star-independent astrometry parameters. */
    IAU::Apcs($date1, $date2, $pv, $ebpv, $ehp, $astrom);

    /* Finished. */
  }