!-----------------------------------------------------------------------
!     am 2001-8-17
!     to get magnetic longitude (xmlon) for subsolar point for specific data
!     used for calculating the equivalent current function
!     
      subroutine subsollon(mtime,iyr)
      
      implicit none
    
      integer, intent(in) :: mtime(3),iyr
!   
      real :: xmlon,date,colat,elon,vp,sbsllat,sbsllon
      common/ssolar/ xmlon,date,colat,elon,sbsllat,sbsllon
      
      integer :: iday,ihr,imn
      real :: sec
! 
!  input: iyr,iday,ihr,imn,sec
!         IYR  = Year (e.g., 1994). IYR must be in the range: 1601 to 2100.
!         IDAY = Day number of year (e.g., IDAY = 32 for Feb 1)
!	  IHR  = Hour of day	(e.g., 13 for 13:49)
!	  IMN  = Minute of hour (e.g., 49 for 13:49)
!	  SEC  = Second and fraction after the hour/minute.
!  output:  SBSLLAT = geographic latitude of subsolar point (degrees)
!	    SBSLLON = geographic longitude of subsolar point (degrees,
!		      between -180 and +180)	 
      iday = mtime(1)
      ihr  = mtime(2)
      imn  = mtime(3)
      sec  = 0.
      
      write (6,'(1x,/,'' SUBSOL inputs: iyr, iday, ihr, imn, sec ='',
     |           4i5,f5.0,'' UT '')') iyr,iday,ihr,imn,sec
      
      call subsol(iyr,iday,ihr,imn,sec,sbsllat,sbsllon)
      
!      write (6,'('' SUBSOL returns: sbsllat,sbsllon ='',2f8.2, 
!     |           '' deg '')') sbsllat,sbsllon
!      write (6,*) ' '

      date = float(iyr) + float(iday)/365. + float(ihr)/24./365.
      
! 
!  cofrm: assign DGRF/IGRF spherical harmonic coefficients
!         cofrm must be called before calling DYPOL!
!  dypol: computes parameters for dipole component of geomagnetic field.
!
!  input: from COFRM through COMMON /MAGCOF/ NMAX,GB(144),GV(144),ICHG
!	NMAX = Maximum order of spherical harmonic coefficients used
!	GB   = Coefficients for magnetic field calculation
!	GV   = Coefficients for magnetic potential calculation
!	ICHG = Flag indicating when GB,GV have been changed
!
!  output: COLAT = Geocentric colatitude of geomagnetic dipole north pole (deg)
!	   ELON  = East longitude of geomagnetic dipole north pole (deg)
!	   VP	 = Magnitude, in T.m, of dipole component of magnetic
!	           potential at geomagnetic pole and geocentric radius
!	           of 6371.2 km
 
      call cofrm(date)
      call dypol(colat,elon,vp)
      
! calculate magn. longitude with geocentric spherical
! latitude and longitude of sbsllat,sbsllon
!   colat = geocentric colatitude of geomagnetic dipole north pole (deg)
!   elon  = east longitude of geomagnetic dipole north pole (deg)
!   input: sbsllat,sbsllon,colat,elon
!   output: xmlon ! geomagnetic dipole longitude of the point

!      write(6,*) ' colatitude of geomagnetic dipole north pole colat= ',
!     |            colat
!      write(6,*) ' East longitude elat= ',elon 
 
      call solgmlon(sbsllat,sbsllon,colat,elon,xmlon)
      
      write (6,'(1x,/,'' SOLGMLON returns:  XMLON = ''
     |           f11.3,'' deg '',f11.3,'' deg '')') xmlon,sbsllon
      
  
      end subroutine subsollon