SUBROUTINE buvplot
C Plots observed u-v coverage, including different symbol sizes
C for different observed visibility amplitudes. Uses
C PGPLOT package.  Note that PGPLOT wants REAL*4 reals.
C     C.A. Hummel    June 18, 1991

      INCLUDE 'BINFIT.INC'
      real*4 u(mxrec,mxfilt),v(mxrec,mxfilt)
      real*4 umax,umin,vmax,vmin
      real*4 vismax(mxfilt),vismin(mxfilt)
      character*40 title
      character*8 plotfile
      character*4 plot_dev
      integer*4 ier,date,nplots,isymb
      integer*4 pgbegin
      logical*1 hcopy

      external pgbegin

      ier=1
      hcopy=.false.
      plotfile='UV   .ps' 
      nplots=0
      
C Find the minimum and maximum u's, v's, and visibilities

      umax=0
      umin=0
      vmax=0
      vmin=0
    5 do ig=1,nfilt
       vismax(ig)=0
       vismin(ig)=1
       do id=1,ndata
        u(id,ig)=-udata(id,ig)/1000000.
        v(id,ig)=vdata(id,ig)/1000000.
        umax=max(umax,u(id,ig),-u(id,ig))
        umin=min(umin,u(id,ig),-u(id,ig))
        vmax=max(vmax,v(id,ig),-v(id,ig))
        vmin=min(vmin,v(id,ig),-v(id,ig))
        if(obsvis2(id,ig).ne.2)then
        vismax(ig)=max(vismax(ig),obsvis2(id,ig))
        vismin(ig)=min(vismin(ig),obsvis2(id,ig))
        endif
       enddo
      enddo
      vmax=vmax*1.1
      vmin=vmin*1.1
      umax=umax*1.1
      umin=umin*1.1

      write(title,'(a,a,i4,a,i2,a,i6)')
     1 starname(1:8),' = FK ',starno,'  Baseline: ',
     2 baseline(1),'  ',date      

   10 if(hcopy)then
       write(outc,*)' Making hardcopy'
       ier=pgbegin(0,plotfile//plot_dev,1,1)
      else
       ier=pgbegin(0,'/ega',1,1)
      endif
      if(ier.ne.1)return
      call pgscf(1)         ! 1=Plain font, 2=Roman, 3=Italic, 4=Script
      call pgsch(1.2)        ! Set character height
      call pgsci(5)         ! 1=white, 5=cyan
      call pgenv(umin,umax,vmin,vmax,1,0)
      call pglabel('-u (millions of wavelengths)',
     1             'v (millions of wavelengths)',title)

      do ig=1,nfilt
       if(ig.eq.1)call pgsci(2)
       if(ig.eq.2)call pgsci(4)
       if(ig.eq.3)call pgsci(3)
       do id=1,ndata
        isymb=int((abs((obsvis2(id,ig)-vismin(ig))*0.34
     1  /(vismax(ig)-vismin(ig)))+1.)*20.)
        call pgpoint(1,u(id,ig),v(id,ig),isymb)
        call pgpoint(1,-u(id,ig),-v(id,ig),isymb)
       enddo
      enddo
      
       call pgend
       hcopy=.false.
   19  if(query(' Make a hard copy (y/n)?'))then
        hcopy=.true.
        plot_dev='/vps'
        nplots=nplots+1
        write(plotfile(3:5),'(i3.3)')nplots
        write(outc,*)' Creating file ',plotfile//plot_dev,' OK?'
        read(inc,*)answer
        call caps(answer)
        if(answer.ne.'Y')goto 19
        goto 10
       elseif(query(' Repeat the screen plot? (y/n)'))then
        goto 5
       endif
      return
      END