C+
C NAME:
C	STEREOB8
C PURPOSE:
C	Returns the heliographic or ecliptic longitude (in degrees) of the
C	sub-Earth point
C CATEGORY:
C	Celestial mechanics
C CALLING SEQUENCE:
	function STEREOB8(iYrIn,Doy8)
C INPUTS:
C	iYrIn	 integer	year
C				(if iYr<0 then the ecliptic longitude is returned)
C	Doy	 real		day of year, including fraction for time of day
C OUTPUTS:
C	STEREOB8 real		heliographic longitude (degrees, 0<=EARTH<360)
C CALLS:
C	SunNewcomb, ECLIPTIC_HELIOGRAPHIC
C SEE ALSO:
C	XMAP_SC_POS
C PROCEDURE:
C	Typically used as external function to e.g. href=XMAP_SC_POS
C MODIFICATION HISTORY:
C	JAN-1991, Paul Hick (UCSD/CASS)
C	JUL-1993, Paul Hick (UCSD/CASS; pphick@ucsd.edu), added option to return ecliptic longitude
C-
	    integer	iYrIn
	    real*8	Doy8

	    real	RVect(3),VVect(5)

	iYr = abs(iYrIn)

C	call SunNewcomb(0,iYr,Doy,rLng,rLat,rDist)
	call stereoBOrbit(iYr,sngl(Doy8),RVect,VVect)
	XLNG = mod(RVect(1)+180.0,360.0)
	XLAT = RVect(2)

	if (iYrIn .ge. 0) then
	    call ECLIPTIC_HELIOGRAPHIC(0,iYr,sngl(Doy8),XLNG,XLAT)
	end if
	STEREOB8 = XLNG

	return
	end