C+
C NAME:
C	HELIOS_1
C PURPOSE:
C	Returns the heliographic or ecliptic longitude of the Helios 1
C	spacecraft for a given time
C CATEGORY:
C	Celestial mechanics
C CALLING SEQUENCE:
	function HELIOS_1(iYrIn,Doy)
C INPUTS:
C	iYr		integer		year
C					(if iYr < 0 then then the ecliptic longitude is returned)
C	Doy		real		day of year, including fraction for time of day
C OUTPUTS:
C	HELIOS_1	real		heliographic longitude (degrees, 0<=EARTH<360)
C CALLS:
C	ECLIPTIC_HELIOGRAPHIC, HOSOrbit
C PROCEDURE:
C	The spacecraft is assumed to move in the ecliptic
C MODIFICATION HISTORY:
C	JAN-1991, Paul Hick (UCSD)
C-
	    integer	iYrIn
	    real	Doy

	iYr = abs(iYrIn)
	call HOSOrbit(1,iYr,Doy,XDIS,HELIOS_1,VR,VT)
	if (iYrIn .ge. 0) then
	    XLAT = 0.
	    call ECLIPTIC_HELIOGRAPHIC(0,iYr,Doy,HELIOS_1,XLAT)
	end if

	return
	end