SUBROUTINE CALVIS(ndata,nfilt,maxnd,maxnf,date,baseline,hours,
     &                  lambda,modvis2,udata,vdata,
     &                  stars,calstars,caldiams)
C
C Calculate the visibilities of a single star with uniform disk
C
      include 'constnts.inc' 

      integer*4 ndata,nfilt,maxnd,maxnf
      integer*4 date(maxnd),baseline(maxnd)
      integer*4 calstars(*),stars(*)
      real*8 hours(maxnd),lambda(maxnd,maxnf)
      real*8 udata(maxnd,maxnf),vdata(maxnd,maxnf),modvis2(maxnd,maxnf)
      real*8 arg,bessj1,caldiams(*)
C-------------------------------------------------------------------
C Calculate predicted visibilities for each baseline and data record
C inlambda in nm, u and v in wavelengths

      DO ID=1,NDATA
      DO IG=1,NFILT

      do i=1,mxstars
       if(stars(id).eq.calstars(i))then
        istar=i
       endif
      enddo
      arg=0.015231D-6*sqrt(udata(id,ig)**2+vdata(id,ig)**2)
     &               *caldiams(istar)/(0.91D0+72.D0/lambda(id,ig))
      if(arg.ne.0)then
       modvis2(id,ig)=(2.D0*abs(bessj1(arg))/arg)**2
      else
       modvis2(id,ig)=1.D0
      endif

      ENDDO
      ENDDO

      RETURN
      END