def plotTrack(self,d1='x',d2='z',interp=True,spread=0,simple=_USESIMPLE,
                  *args,**kwargs):
        """
        NAME:

           plotTrack

        PURPOSE:

           plot the stream track

        INPUT:

           d1= plot this on the X axis ('x','y','z','R','phi','vx','vy','vz','vR','vt','ll','bb','dist','pmll','pmbb','vlos')

           d2= plot this on the Y axis (same list as for d1)

           interp= (True) if True, use the interpolated stream track

           spread= (0) if int > 0, also plot the spread around the track as spread x sigma

           scaleToPhysical= (False), if True, plot positions in kpc and velocities in km/s

           simple= (False), if True, use a simple estimate for the spread in perpendicular angle

           bovy_plot.bovy_plot args and kwargs

        OUTPUT:

           plot to output device

        HISTORY:

           2013-12-09 - Written - Bovy (IAS)

        """
        if not hasattr(self,'_ObsTrackLB') and \
                (d1.lower() == 'll' or d1.lower() == 'bb' 
                 or d1.lower() == 'dist' or d1.lower() == 'pmll' 
                 or d1.lower() == 'pmbb' or d1.lower() == 'vlos'
                 or d2.lower() == 'll' or d2.lower() == 'bb' 
                 or d2.lower() == 'dist' or d2.lower() == 'pmll' 
                 or d2.lower() == 'pmbb' or d2.lower() == 'vlos'):
            self.calc_stream_lb()
        phys= kwargs.pop('scaleToPhysical',False)
        tx= self._parse_track_dim(d1,interp=interp,phys=phys)
        ty= self._parse_track_dim(d2,interp=interp,phys=phys)
        bovy_plot.bovy_plot(tx,ty,*args,
                            xlabel=_labelDict[d1.lower()],
                            ylabel=_labelDict[d2.lower()],
                            **kwargs)
        if spread:
            addx, addy= self._parse_track_spread(d1,d2,interp=interp,phys=phys,
                                                 simple=simple)
            if ('ls' in kwargs and kwargs['ls'] == 'none') \
                    or ('linestyle' in kwargs \
                            and kwargs['linestyle'] == 'none'):
                kwargs.pop('ls',None)
                kwargs.pop('linestyle',None)
                spreadls= 'none'
            else:
                spreadls= '-.'
            spreadmarker= kwargs.pop('marker',None)
            spreadcolor= kwargs.pop('color',None)
            spreadlw= kwargs.pop('lw',1.)
            bovy_plot.bovy_plot(tx+spread*addx,ty+spread*addy,ls=spreadls,
                                marker=spreadmarker,color=spreadcolor,
                                lw=spreadlw,
                                overplot=True)
            bovy_plot.bovy_plot(tx-spread*addx,ty-spread*addy,ls=spreadls,
                                marker=spreadmarker,color=spreadcolor,
                                lw=spreadlw,
                                overplot=True)            
        return None
NAME:

           plotTrack

        PURPOSE:

           plot the stream track

        INPUT:

           d1= plot this on the X axis ('x','y','z','R','phi','vx','vy','vz','vR','vt','ll','bb','dist','pmll','pmbb','vlos')

           d2= plot this on the Y axis (same list as for d1)

           interp= (True) if True, use the interpolated stream track

           spread= (0) if int > 0, also plot the spread around the track as spread x sigma

           scaleToPhysical= (False), if True, plot positions in kpc and velocities in km/s

           simple= (False), if True, use a simple estimate for the spread in perpendicular angle

           bovy_plot.bovy_plot args and kwargs

        OUTPUT:

           plot to output device

        HISTORY:

           2013-12-09 - Written - Bovy (IAS)