NAME:
	UBVConst
 PURPOSE:
	Defines apparent solar magnitudes and limb darkening
	constants to be used for the Helios UBV system
 CALLING SEQUENCE:
	R = UBVConst(C)
 INPUTS:
	C			scalar; type: integer
					1,2,3 for U,B,V light, resp.
 OUTPUTS:
	R			array[2]; type: float
					R[0]:	limb darkening constant
					R[1]:	apparent magnitude of the Sun
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
 CALLED BY:
	RemoteView_Display2D, vu_earthskymap
 RESTRICTIONS:
	1<=C<=3; if C out of range then C=1 is used
 PROCEDURE:
 >	UHOS(LT) is the limb darkening coefficient for Helios photometer
	light from the U/B/V filter (C=1,2,3). From a graph in
	RAUMFAHRTFORSCHUNG by LEINERT et al. LAMBDA=3650,4300,5250 A for U,B,V
	light. From Allen (1985), p. 171, U=0.80,0.77,0.62 by linear
	interpolation.
 >	LUM is the luminosity of the solar disk in E14 S10 units:
	LUM = LSUN/LS10 = 10**((10-MSUN)/2.5), with MSUN (from Allen)
	-25.96,-26.09,-26.73 for U,B and V light respectively.
 MODIFICATION HISTORY:
	JUL-1996, Paul Hick (UCSD)

 NAME:
	UlyssesOrbit
 PURPOSE:
	Calculate position of Ulysses
 CATEGORY:
	smei/gen/idl/ephem
 CALLING SEQUENCE:
	FUNCTION UlyssesOrbit, T, degrees=degrees
 INPUTS:
	T		array[n]; type: time structure
				times at which s/c positions are needed
 OPTIONAL INPUT PARAMETERS:
	/degrees	if set then angles are output in degrees (default: radians)
 OUTPUTS:
	Result	array[3,*]; type: float
				ecliptic longitude (deg/rad), latitude (deg/rad) and distance (AU)
				the angular units depend on the setting of /degrees
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
 CALLS: ***
	KeplerOrbit, TimeGet, TimeSet, ToRadians
 CALLED BY:
	big_eph
 PROCEDURE:
	Earth-Jupiter segment (valid from 16 Oct 1990-30 Dec 1991)
	a =     8.9915 AU (1345106000 km)
	e =     0.889166
	i =     1.990719 deg.
	Omega = 12.85909 deg.
	w =     7.72595 deg.
	M =     0.0365574*(J - 2448177.0755) deg.
   	     where J is the Julian date of interest

	Final Out-of-ecliptic Orbit (valid from 19 Mar 1992-31 Dec 2001)
	a =     3.3730032 AU (504594094 km)
	e =     0.60306
	i =     79.12801 deg.
	Omega = -22.51862 deg.
	w =     -1.11377 deg.
	M =     0.1591096*(J - 2449788.986) deg.
 MODIFICATION HISTORY:
	SEP-1999, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	unexpected_event
 PURPOSE:
       Used to process unexpected events in widgets (i.e. events which are
	ignored by the event handler).
 CATEGORY:
 CALLING SEQUENCE:
	unexpected_event, event [,/destroy]
 INPUTS:
	event		array[1]; type: structure
				the event structure passed to the event handler
 OPTIONAL INPUT PARAMETERS:
	/destroy	if set, the event structure is destroyed (i.e. the scalar
			value 0L is returned in the input argument 'event'
 OUTPUTS:
	event		if /destroy is set then event=0L is returned;
			if /destroy NOT set the input event structure is not modified
 CALLSE;
	InitVar
 CALLS: ***
	InitVar
 CALLED BY:
	qEphem, qImage, qImage_cw, qLoadCT, qShow, qTool, qView, qslider_cw, qsmei_sky, qvox, qvu
 PROCEDURE:
	The name of the structure is displayed, with a list of all structure fields
 MODIFICATION HISTORY:
       JULY-2001, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	unhide_env
 PURPOSE:
	
 CATEGORY:
	gen/idl/toolbox
 CALLING SEQUENCE:
	spec = unhide_env(env_spec [,/directory]
 INPUTS:
	hidden_spec 	scalar; type: string
						file or directory specification
						Usually starts with a $-sign
 OPTIONAL INPUTS:
	/directory		if set and hidden_spec='', then the
						current directory is used
 OUTPUTS:
	spec			scalar; type: string
						hidden_spec with the env var translated.
						If something goes wrong (the env var
						doesn't exist or points to a non-existent
						directory, then spec = '' is returned
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
 CALLS: ***
	CheckDir, FILEPATH, GetFileSpec, InitVar, os_separator
 CALLED BY:
	qImage_Pick, qView_FileFilter, qView_PickFiles, qsmei_sky_Pick
 PROCEDURE:
 MODIFICATION HISTORY:
	JUL-2005, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	unitvectors
 PURPOSE:
	Find two orthogonal unit vectors perpendicular to vector r.
 CATEGORY:
	gen/idl/toolbox/math
 CALLING SEQUENCE:
	axes = unitvectors(r)
 INPUTS:
	r		array[3]; type: float
 OPTIONAL INPUT PARAMETERS:
	/sphere, /cylin, /rect
				indicates the coordinate system used: spherical, cylindrical
				or rectangular; default: rectangular
	/degrees	if spherical or cylindrical coordinates are used, setting this
				keyword indicates that the angles are in degrees; default: radians
	/ascending	See PROCEDURE.
 OUTPUTS:
	axes	array[3,3]; type:float
				x,y,z coordinates of three perpendicular unit vectors
				axes[*,2] is a unit vector parallel to the input vectors r
 OPTIONAL OUTPUT PARAMETERS:
 INCLUDE:
	@compile_opt.pro			; On error, return to caller
 CALLS: ***
	CV_COORD, InitVar, SuperArray, T3D, WhatIs, vectorproduct
 CALLED BY:
	arrow3d, qvu_draw
 RESTRICTIONS:
	The input vector must have a non-zero length
 PROCEDURE:
 >	The unit vectors are returned so that axes[*,0], axes[*,1], axes[*,2] form
	a right-handed coordinate system with z-axis (axes[*,2]) along the input
	vector r, the x-axis (axes[*,0]) in the original x-y plane (i.e. pointing to
	either the ascending or descending node)
 > If /ascending is NOT set then the y-axis (axes[*,1]) will always have a positive
	z-component
 > If /ascending is SET then the x-axis is always pointing to the ascending
	node. The z-component of the y-axis will have the same sign as the z-component
	of the input vector.
 MODIFICATION HISTORY:
	AUG-1999, Paul Hick (UCSD/CASS)
	SEP-2006, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
		Treat special case where input vector is along z-axis separately.

 NAME:
	usno_body
 PURPOSE:
	Get list of asteroids for which ephemerides are available
 CATEGORY:
	smei/gen/idl/ephem; USNO Asteroid Ephemeris
 CALLING SEQUENCE:
	FUNCTION usno_body, asteroid,	$
		file	= file	, $
		silent	= silent, $
		number	= number, $
		index	= index	, $
		count	= count	, $
		total_count=total_count
 OPTIONAL INPUT PARAMETERS:
	asteroid		scalar or array; type: integer or string
						integer: list of asteroid numbers
						string : list of asteroid names
							only valid entries on this list are processed
							If not specified then all asteroids are processed
 OUTPUTS:
	Result			array[count]; type: string
						list of asteroid names for which ephemeris files
						are available; if none exist (count=0) then names=''
 OPTIONAL OUTPUT PARAMETERS:
	count=count 	scalar; type: integer
						# requested asteroids for which ephemeris files are present
						i.e. # elements in input 'asteroid' with invalid entries
						removed.
	file=file		array[count]; type: string
						file names of the ephemeris files; null-string if count=0
	number=number	array[count]; type: integer
						asteroid numbers; -1 if count=0
	index=index 	array[count]; type: integer
						index numbers between 0, and total_count-1; -1 if count=0
	total_count=total_count
					scalar; type: integer
						total # asteroids for which ephemeris files are present
	/silent			if set, informational messages are suppressed
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
 CALLS: ***
	FILEPATH, GetFileSpec, IsType, SetFileSpec, where_common, who_am_i
 CALLED BY:
	big_body, big_eph, big_orbit, smei_frm_where, usno_eph, usno_init
 PROCEDURE:
 >	The following 15 asteroids are available from the USNO AE98 ephemeris:
		'Ceres','Pallas','Juno','Vesta','Hebe','Iris','Flora','Metis','Hygiea',
		'Eunomia','Psyche','Europa','Cybele','Davida','Interamnia'
	The corresponding asteroid numbers are
		1,2,3,4,6,7,8,9,10,15,16,52,65,511,704.
	The returned list of asteroid names are take from this list.
 >	The asteroid files are searched for in the subdirectory 'usno' of the
	directory where this procedure is located.
 MODIFICATION HISTORY:
	SEP-1999, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	usno_close
 PURPOSE:
	Closes asteroid ephemeris files and frees heap memory used by ephemeris
 CATEGORY:
	smei/gen/idl/ephem; USNO Asteroid Ephemeris
 CALLING SEQUENCE:
	usno_close
 INPUTS:
	(none)
 OUTPUTS:
	(none
 CALLED BY:
	big_eph, smei_frm_where, usno_test
 SEE ALSO:
	usno_init
 CALLS:
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
 COMMON BLOCKS:
	common USNO_INFO, USNO_PNTR
 SIDE EFFECTS:
	Opens an ephemeris file and defines a heap variable.
 RESTRICTIONS:
	usno_close must be called separately to close all open asteroid
	files and free the memory used by the heap variables.
 PROCEDURE:
 >	Common block USNO_INFO contains the pointer array USNO_PNTR.

 >	If a pointer in the array is a valid heap pointer, then the associated asteroid
	has been initialized (file is open; heap variable exists).
	After usno_close is finished all asteroid files should be close
	and all heap memory released.
 MODIFICATION HISTORY:
	SEP-1999, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
		Modified from USNO AE98 C-software

 NAME:
	usno_eph
 PURPOSE:
	Get position and velocity of asteroid from USNO AE98 ephemerides
 CATEGORY:
	smei/gen/idl/ephem; USNO Asteroid Ephemeris
 CALLING SEQUENCE:
	FUNCTION usno_eph, UT, body, center=center, $
		location	= location	, $
		speed		= speed 	, $
		to_sphere	= to_sphere , $
		degrees 	= degrees	, $
		precess 	= precess	, $
		to_ecliptic = to_ecliptic,$
		get 		= get		, $
		silent		= silent
 INPUTS:
	UT		scalar; type: double
					Julian date when ephemerides are needed
	body	scalar; type: string or integer; default: 'ceres'
					asteroid name or asteroid number (see: usno_body)
 OPTIONAL INPUT PARAMETERS:
	center=center
			scalar; type: integer; default: jpl_body(/sun)
					by default, heliocentric coordinates are returned.
					if center is set to a non-zero value between 1 and 9
					then the coordinates are centered on the corresponding
					planet (e.g. center=3 returns geocentric coordinates)
 OUTPUTS:
	Result	array[6] or array[6,*]; type: double
					array[0:2,*] = position in AU
					array[3:5,*] = velocity in AU/day
					If the asteroid ephemeris could not be determined
					(because the ephemeris file could not be located or because
					the Julian day JD is outside the range of the ephemeris)
					then all six components are set to the double precision NaN
					value !values.d_nan.
 OPTIONAL OUTPUT PARAMETERS:
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
 CALLS: ***
	AngleRange, BadValue, CV_COORD, CvPrecess, CvSky, InitVar, IsTime, IsType, TimeGet
	TimeSet, jpl_eph, usno_body, usno_init, usno_maket, usno_read
 CALLED BY:
	big_eph, smei_frm_where, usno_test
 COMMON BLOCKS:
	common USNO_INFO, USNO_PNTR
 RESTRICTIONS:
	If the center keyword is used then the jpl ephemeris is
	initialized. Close the ephemeris using jpl_close.
 PROCEDURE:
 >	If the asteroid keyword is not specified than usno_eph calls itself
	recursively to loop over all available asteroids.
 MODIFICATION HISTORY:
	SEP-1999, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
		Modified from USNO AE98 C-software

 NAME:
	usno_init
 PURPOSE:
	Initialize and close USNO AE98 asteroid file
 CATEGORY:
	smei/gen/idl/ephem; USNO Asteroid Ephemeris
 CALLING SEQUENCE:
	ast = usno_init(asteroid)
 INPUTS:
	asteroid	scalar; type: string or integer
					asteroid name or asteroid number (see: usno_body)
 OUTPUTS:
	ast_index	scalar; type: integer
					index of asteroid in pointer array USNO_PNTR
					ast=-1 if the initialized failed (probably because the
					asteroid files couldn't be located (see usno_body).
 CALLED BY:
	usno_eph
 SEE ALSO:
	usno_body, usno_close
 CALLS: ***
	InitVar, IsType, usno_body, usno_read
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
 COMMON BLOCKS:
	common USNO_INFO, USNO_PNTR
 SIDE EFFECTS:
	Opens an ephemeris file and defines a heap variable.
 RESTRICTIONS:
	usno_close must be called separately to close all open asteroid
	files and free the memory used by the heap variables.
 PROCEDURE:
 >	Common block USNO_INFO contains the pointer array USNO_PNTR.

 >	An asteroid is initialized by opening the asteroid file, reading the
	header and first record of Chebyshev coefficients, and setting up
	a structure in heap memory pointed to by one of the pointers
	in USNO_PNTR.
 >	Fhe structure is set up as follows:
	USNO_PNTR[ast] = ptr_new( {USNO_STRUCT,	$
		iU		: iU,				$		logical unit of asteroid file
		name	: ast_name,			$		name of asteroid (see usno_body)
		number	: ast_number,		$		number of asteroid (see usno_body)
		jdi		: jdi,				$		start JD of ephemeris file
		jdf		: jdf,				$		end JD of ephemeris file
		jd		: ptr_new(jd)	,	$		start JDs for each record in file
		span	: ptr_new(span)	,	$		periods covered by each record (days)
		order	: ptr_new(order),	$		order of Chebyshev polynomial for each record
		currec	: long(0),			$		current record
		curjd	: double(-1),		$		start JD of current record
		curspan	: double(-1),		$		period covered by current record
		curorder: long(-1),			$		order of Chebeshyv polynomial for current record
		coef	: dblarr(14,3)})			Chebyshev coefficients (only coef[0:order;*] is used)
 >	The pointer USNO_PNTR[ast] is first checked for validity. If it is a valid heap
	pointer then the asteroid has been initialized already, and usno_init quietly returns.
	USNO_PNTR is an array of heap pointers (one for each asteroid).

 MODIFICATION HISTORY:
	SEP-1999, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
		Modified from USNO AE98 C-software

 NAME:
	usno_maket
 PURPOSE:
	Calculates the Chebyshev polynomials for the USNO asteroid ephemeris
 CATEGORY:
	smei/gen/idl/ephem; USNO Asteroid Ephemeris; Chebyshev interpolation
 CALLING SEQUENCE:
	usno_maket, time, t, tdot
 INPUTS:
	time	scalar; type: double
				Chebyshev time (-1<=time<1)
 OUTPUTS:
	t		scalar; type: double
				Chebyshev polynomial at 'time'
	tdot	scalar; type: double
				derivative of Chebyshev polynomial at 'time'
 CALLED BY:
	usno_eph
 PROCEDURE:
	Compute the values for the Chebyshev polynomial and their derivatives
	to thirteenth order for a given time
 MODIFICATION HISTORY:
	SEP-1999, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
		Converted from USNO AE C-software

 NAME:
	usno_read
 PURPOSE:
	Reads a record from an ephemeris file
 CATEGORY:
	smei/gen/idl/ephem; USNO Asteroid Ephemeris
 CALLING SEQUENCE:
	usno_read, ast
 INPUTS:
	ast		scalar; type: integer
				indicates the position of the asteroid in the pointer
				array USNO_PNTR
 OUTPUTS:
	Sets several members of the asteroid structure for asteroid 'ast':
 OPTIONAL OUTPUT PARAMETERS:
 CALLED BY:
	usno_eph, usno_init
 COMMON BLOCKS:
	common USNO_INFO, USNO_PNTR
 SIDE EFFECTS:
 RESTRICTIONS:
	The file pointer must be put at the proper position
	before calling usno_read. This is done by usno_eph.
	(*(USNO_PNTR[ast])).curjd		start Julian day for record
	(*(USNO_PNTR[ast])).curspan		period covered by record (days)
	(*(USNO_PNTR[ast])).curorder	order of Chebyshev polynomial
	(*(USNO_PNTR[ast])).coef		Chebyshev coefficients
 PROCEDURE:
	Unformatted read
 MODIFICATION HISTORY:
	SEP-1999, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	usno_test
 PURPOSE:
	Test program for USNO asteroid ephemerides
 CATEGORY:
	smei/gen/idl/ephem; USNO Asteroid Ephemeris; Test program
 CALLING SEQUENCE:
	usno_test, asteroid
 INPUTS:
	asteroid		scalar; type: string
						one of the following:
			 ['Ceres','Pallas','Juno','Vesta','Hebe','Iris','Flora',	$
			'Metis','Hygiea','Eunomia','Psyche','Europa','Cybele','Davida','Interamn']
 OUTPUTS:
	(none)
 CALLS: ***
	FILEPATH, InitVar, REVERSE, usno_close, usno_eph, who_am_i
 COMMON BLOCKS:
	common USNO_INFO, USNO_PNTR
 PROCEDURE:
	Compares ephemeris calculation with test numbers for the asteroid used
	(stored in subdirectory 'usno').
 MODIFICATION HISTORY:
	FEB-2000, Paul Hick (UCSD/CASS; pphick@ucsd.edu)