my $lats1=51.4774704;
    my $lats2=51.4774704;
    my $lons1=-0.458850861;
    my $lons2=-0.459365845;
    my $dlats = $lats2 - $lats1;
    my $dlons= $lons2 - $lons1;
    
    my $y1 = sin( $dlons / 180 ) * cos( $lats2 /180 );
    my $x1 = cos( $lats1 /180 ) * sin( $lats2/180 ) - sin( $lats1/180 ) * cos( $lats2/180 ) * cos( $dlons/180 );
    
    printf  "heading: %d\n", atan2( $y1, $x1 ) * 57.2957795