NAME:
	HLngEarth
 PURPOSE:
	Returns the heliographic or ecliptic longitude (in degrees) of the
	sub-Earth point
 CATEGORY:
	Celestial mechanics
 CALLING SEQUENCE:
	double precision function HLngEarth(tt)
 INPUTS:
	tt(2)		integer			2-element standard time
 OUTPUTS:
	HLngEarth	double precision	heliographic longitude (degrees, in [0,360)
 CALLS: ***
	Time2EclipticHeliographic, Time2SunNewcomb
 CALLED BY:
	Time2Carrington
 SEE ALSO:
	XMAP_SC_POS
 PROCEDURE:
	Typically used as external function to e.g. XMAP_SC_POS
 MODIFICATION HISTORY:
	JAN-1991, Paul Hick (UCSD/CASS)
	JUL-1993, Paul Hick (UCSD/CASS; pphick@ucsd.edu), added option to return ecliptic longitude

 NAME:
	HLngEastLimb
 PURPOSE:
	Returns the heliographic or ecliptic longitude (in degrees) of the
	solar east limb
 CALLING SEQUENCE:
	double precision function HLngEastLimb(tt)
 INPUTS:
	tt(2)		integer			2-element standard time
 OUTPUTS:
	HLngEastLimb	double precision	heliographic longitude (degrees, in [0,360)
 CALLS: ***
	Time2EclipticHeliographic, Time2SunNewcomb
 SEE ALSO:
	XMAP_SC_POS
 PROCEDURE:
	Typically used as external function to e.g. XMAP_SC_POS
 MODIFICATION HISTORY:
	???-????, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	HLngWestLimb
 PURPOSE:
	Returns the heliographic or ecliptic longitude (in degrees) of the
	solar west limb
 CALLING SEQUENCE:
	double precision function HLngWestLimb(tt)
 INPUTS:
 INPUTS:
	tt(2)		integer			2-element standard time
 OUTPUTS:
	HLngWestLimb	double precision	heliographic longitude (degrees, in [0,360)
 CALLS: ***
	Time2EclipticHeliographic, Time2SunNewcomb
 SEE ALSO:
	XMAP_SC_POS
 PROCEDURE:
	Typically used as external function to e.g. XMAP_SC_POS
 MODIFICATION HISTORY:
	???-????, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	HOSInquire
 PURPOSE:
	Determine record length for a Helios file
 CATEGORY:
	Kludge
 CALLING SEQUENCE:
	subroutine HOSInquire(cFile,iRecl)
 INPUTS:
	cFile	character*(*)	file name
 OUTPUTS:
	iRecl	integer		record length in 4-byte words (usually 37 or 6)
				= 0 if not succesful
 CALLED BY:
	iOpenFile [1], iOpenFile [2], iOpenFile [3]
 INCLUDE:
	include		'dirspec [1].h'
	include		'dirspec [2].h'
	include		'dirspec [3].h'
	include		'dirspec [4].h'
 CALLS: ***
	CvSwap, Say, bGetLun, iFreeLun
 RESTRICTIONS:
	It is assumed that the record length is an integer number of
	longwords (4-byte words).
 PROCEDURE:
 >	This kludge is necessary for DOS, Unix and Linux. Helios files are opened as
	direct access files. It is necessary to explicitly use the recl
	keyword to provide the record length in bytes (in VMS this is not necessary).
 >	The resulting record length can be used directly in an open statement:
		open (iU, file=cFile, status='OLD',access='DIRECT', recl=iRecl)
	This should work both under DOS, VMS and Linux. Unix has not been tried yet.
 >	First an inquire by name is tried.
	VMS returns the record length in bytes; this is converted to longword.
	DOS returns a zero-record length.
	The record length is determined from the file content by
	looking for photometer/color combinations.
 MODIFICATION HISTORY:
	JUN-1998, Paul Hick (UCSD/CASS)
	JAN-2003, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
		Photometer values are now tested for values 1,2,3. If the first photometer
		value read from file is not one of these, then bytes are swapped and the
		same test is done again. If swapping bytes changes the photometer value to
		1,2 or 3 then byte swapping is applied to all integers read from file.
		This should allow the routine to work when Helios files created on VMS, Windows
		or Linux are opened on a Unix machine and v.v. (iHOSRead uses the same trick)