C+
C NAME:
C	JD_SYNC
C PURPOSE:
C CATEGORY:
C CALLING SEQUENCE:
	subroutine JD_SYNC(IJD,EARTH,bForeCast,XCbeg,XCtst,JDref,JDcntr,XCEarth,LatEarth,nCar,JDCar)
C INPUTS:
C OUTPUTS:
C CALLS:
C	Julian, SunNewcomb, ECLIPTIC_HELIOGRAPHIC, XMAP_SC_POS, FLINT8
C INCLUDE:
	include		'sun.h'
C EXTERNAL:
	external	EARTH
C PROCEDURE:
C MODIFICATION HISTORY:
C	JUN-1995, Paul Hick (UCSD)
C-
	logical		bForeCast
	real*8		JDref
	real*8		JDcntr
	real*8		JDCar(nCar)
	real*8		JD
	real*8		rLng
	real*8		rLat
	real*8		rDis
	real*8		FLINT8
	real		LngEarth,LatEarth

	if (bForeCast) then			! JDref is input: start JD for search
	    JDcntr = JDref			! JD at center of plot
	    call Julian(IJD+1,iYr,Doy,JDcntr,JD)
	    XCEarth = XMAP_SC_POS(EARTH,iYr,Doy,nCar,JDCar)
	    XCbeg   = XCEarth-.5		! XC at center and start of map

	else					! XCbeg is input: XC at start of map
	    XCEarth = XCbeg+.5			! Center of plot
	    JDcntr = FLINT8(1,nCar,JDCar,dble(XCEarth),0d0) ! JD for plot center
	    if (IJD .eq. 10) JDcntr = JDcntr-SUN__MJDtoJD
	    call Julian(IJD+1,iYr,Doy,JDcntr,JD)
	    if (JDref .eq. -1.) then
		JDref = FLINT8(1,nCar,JDCar,dble(XCtst),0d0)
		if (IJD .eq. 10) JDref = JDref-SUN__MJDtoJD
	    else
		JDref = 0.d0			! Start JD for data search
	    end if

	end if

	call SunNewcomb(0,iYr,Doy,rLng,rLat,rDis)
	LngEarth = mod(sngl(rLng)+180.,360.)
	LatEarth = sngl(rLat)		! Ecliptic coord Earth at time JDref
	call ECLIPTIC_HELIOGRAPHIC(0,iYr,Doy,LngEarth,LatEarth)
					! Convert to heliographic coord
	return
	end