NAME:
	HammerAitoff
 PURPOSE:
	Transforms latitude and longitude to X and Y coordinates in the
	Hammer-Aitoff map projection.
 CALLING SEQUENCE:
	Pos = HammerAitoff(Pos)
 INPUTS:
	Pos 		array[2,n]; type: float
					n locations in the sky
					Pos[0,n]	longitudes
					Pos[1,n]	latitudes in [-90.,90.]
 OPTIONAL INPUT PARAMETERS:
	/degrees	if set then all angles are in degrees (default: radians)

	dabg		array[3]; type: float; default: none
					Euler angles for a rotation to be applied to
					'Pos' prior to the Hammer-Aitoff projection.
					(see FishEye)
	zero_phase	scalar; type: float; default: none
					Additional offset applied to phase angle
					(see FishEye)
 OUTPUTS:
	Pos			array[2,n]; type: float
					X,Y	Cartesian coordinates (same structure as input array)
 CALLS: ***
	AngleRange, EulerRotate, IsType, SyncDims, ToRadians
 CALLED BY:
	ColorSkybox, PlotEarthSkymap, PlotPolarSkymap
 RESTRICTIONS:
 PROCEDURE:
	The Hammer-Aitoff projection is the format used at NOAA SEL; for
	details, see the book Introduction to Map Projections by Porter W.
	McDonnell Jr.

	Pos[0,*] > 0 has X > 0	Pos[1,*] > 0 has Y > 0
	Pos[0,*] < 0 has X < 0	Pos[1,*] < 0 has Y < 0

	The returned coordinates will be in the range -sqrt(2),+sqrt(2) in the vertical
	(latitudinal) direction and -2*sqrt(2),+2*sqrt(2) in the horizontal (longitudinal
	direction).
 MODIFICATION HISTORY:
	NOV-1992, Tom Davidson (UCSD)
	MAR-1999, Paul Hick (UCSD/CASS); added /degrees keyword)
	JAN-2002, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
		Added 'dabg' keyword

 NAME:
	HAVE_COMMAND


 PURPOSE:
	Determine if a shell command exists or not.


 CATEGORY:
	Utils


 CALLING SEQUENCE:
	ihave = have_command(command[, command_path])


 INPUTS:
	command	string	The command for which to search.


 OUTPUTS:
	ihave	bool	1 if the command is found, 0 if it isn't


 OPTIONAL OUTPUTS:
	command_path	string	A fully qualified path to the command.


 RESTRICTIONS:
	Probably Unix/Linux only. Note we use spawn rather than
	file_which as the latter doesn't find shell built in commands.


 MODIFICATION HISTORY:
	Original: 17/2/04; SJT

 NAME:
	hide_env
 PURPOSE:
	Hides explicit directory name
 CATEGORY:
 CALLING SEQUENCE:
	 hidden_name = hide_env(file_name [, env_var=env_var, env_value=env_value])
 INPUTS:
	file_name
 OPTIONAL INPUT PARAMETERS:
	env_var=env_var 	array; type: string; default: none
							list of env var definitions in the form name=value
							If not present then the 'set' command is spawned
							to pick up all env vars.
	exclude=exclude 	list of env vars to be excluded (if they are defined).
	force=force 		if set then the common block with internally saved
						env vars and values is rewritten.
 OUTPUTS:
	hidden_name
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
common hide_env_save
nvar
env_vars
env_values
 CALLS: ***
	CheckDir, FILEPATH, InitVar, IsType, REVERSE, boost, destroyvar
 CALLED BY:
	CheckDir, Get_Page, do_file, flt_read, grd_read, htmd_cat, img_read, mk_flick, mpc_body
	qImage, qView, qView_FileFilter, qView_PickFiles, qsmei_sky_Pick, sgp4_eph, sgp4_tlm
	sgp_body, smei_buf, smei_buf_get, smei_buf_gzip, smei_buf_mget, smei_buf_prep
	smei_buf_read, smei_frm_cp, smei_frm_get, smei_frm_read, smei_frm_write
	smei_getfile, smei_hdr_get, smei_hdr_make, smei_hdr_plot, smei_hdr_update
	smei_htm_testcase, smei_mksidereal, smei_sky_read, smei_star_fit
	smei_star_remove, smei_star_writepnt, smei_zodiac_fit, smei_zodiac_remove
	txt_read, vu_get_page, vu_header, vu_insitu, vu_select, vu_update_marker, vu_write
	wso_read, www_help_crosslinks, www_help_files, www_help_get_header
	www_help_section
 PROCEDURE:
 >	The env variables and their values are saved internally in a common block.
	The common block is rewritten each time env_var is specified.
 >	If env_var is not defined then the 'set' command is spawned to get
	all env variables. This is done only once (unless /force is set).
 > PWD and OLDPWD are added to the list of env vars to be excluded
 MODIFICATION HISTORY:
	AUG-2003, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	HIST_FIND


 PURPOSE:
	Find whether an operation has been applied from the history
	records. 


 CATEGORY:
	UTILS


 CALLING SEQUENCE:
	version = hist_find(process, history)


 INPUTS:
	process	string	The process to look for (e.g. 'Large-scale
			flatfields')
	history	string	The history fields from the fits file
			(extracted as found in the structure format).

 KEYWORD PARAMETERS:
	boolean		If set, then only return a -1/0/1 code rather
			than the version number.
	line_break	If set, then the value lies on the next line,
			rather than on the end of the keyword line		


 OUTPUTS:
	version	int/float/bool	The version number of presence flag
				for the process requested. Note: -1
				indicates the process was not found at all.


 CALLED BY:
	FF_SUMMARY
 MODIFICATION HISTORY:
	Original: 24/3/03; SJT
	Added line_break key and allow "none" as a synonym for "not
	applied": 20/10/03; SJT
	Better type checking: 21/10/03; SJT

 NAME:
	HOSOrbit
 PURPOSE:
	Calculates the position of a Helios spacecraft at a given time
 CATEGORY:
	smei/gen/idl/ephem
 CALLING SEQUENCE:
	R = HOSOrbit(T,hos=Hos [,/degrees])
 INPUTS:
	T			array; type: integer or standard time structure
					times (UT)
	hos=Hos		scalar; type: integer; default: 1
					spacecraft (1=Helios A; 2=Helios B)
 OPTIONAL INPUT PARAMETERS:
	/degrees	if set all angles are returned in degrees	
 OUTPUTS:
	R			array[3,*]; type: float
					longitude, latitude, distance
					(longitude and latitude for Equinox 1975.0 ???)
 INCLUDE:
	@compile_opt.pro		; On error, return to caller
 CALLS: ***
	KeplerOrbit, SuperArray, SyncArgs, TimeGet, ToDegrees
 CALLED BY:
	big_eph
 PROCEDURE:
	The spacecraft orbit is assumed to lie in the ecliptic
	See O. Montenbruck, Practical Ephemeris Calculations, p. 42-45
	Perihelion passages for Helios A:

	year       doy           JD               ecl long perih

	1975      74.38411   2442486.8841             257.8521    !
	1975     264.5102       2677.0102                .8493    !
	1976      89.6610       2867.1610                .8570    !
	1976     279.7965       3057.2965                .8478    !
	1977     103.9367       3247.4367                .8448    !
	1977     294.0973       3437.5973                .8496    !
	1978     119.2591       3627.7591                .8517    !
	1978     309.4239       3817.9239                .8518    !
	1979     134.5879       4008.0879                .8530    !
	1979
	1980     149.9095       4388.4095                .8465    !
	1980     340.2279       4578.7279                .8542    !
	1981     164.978        4768.729              257.978
	1981
	1982
	1982
	1983
	1983

	Perihelion passages for Helios B:

	1976     108.1035    2442885.6035             294.2079     !
	1976     293.7552       3071.2552             294.2007     !
	1977     113.5434       3257.0434             294.2332     !
	1977     299.3565       3442.8565             294.2353     !
	1978     120.2137       3628.7137             294.2470     !
	1978     306.0831       3814.5831             294.2528     !
	1979     126.9678       4000.4678             294.2577     !
	1979     312.8478       4186.3478             294.2553     !
 MODIFICATION HISTORY:
	1990, Paul Hick (UCSD)
	1997, Paul Hick (UCSD), replaced explicit orbit calculation by call to KeplerOrbit
	SEP-1999, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
		added option to set the first argument Yr to a standard time structure

 NAME:
	htmd_cat
 PURPOSE:
	Creates the initial orbit catalogues needed by the
	SMEI indexing daemon.
 CALLING SEQUENCE:
	PRO htmd_cat, camera=camera, mode=mode,	source=source,	$
		dig=dig, destination=destination, smeidb=smeidb
 OPTIONAL INPUTS:
	camera=camera		array or scalar; type: integer; default: [1,2,3]
							SMEI cameras to be processed
	mode=mode			array or scaler; type: integer; default: [0,1,2]
							modes to be processed
	source=source		scalar or array; type: string; default: SMEISKY?
							list of directories with skymaps.
							The default SMEISKY? is translated to all
							directories assigned to env vars $SMEISKYn
	/dig				If /dig is set then the skymaps should be located
							in subdirectories c1,c2,c3.
							IF source=SMEISKY? then always /dig is assumed
	destination=destination
						scalar; type: string; default: $TEMP
							destination directory for the htmd catalogues
	/smeidb 			forces destination=$SMEIDB/cat/list
							(see PROCEDURE)
 INCLUDE:
	@compile_opt.pro
 CALLS: ***
	CheckDir, FILEPATH, FXPAR [1], FXPAR [2], FindAllFiles, GetFileSpec, HEADFITS [1]
	HEADFITS [2], HEADFITS [3], InitVar, TimeSplit, TimeString, TimeUnit, boost
	destroyvar, flt_string, hide_env, smei_frm_name, txt_read
 PROCEDURE:
	The htmd catalogues are derived from the files
	smei_frm_orb_m0.txt, smei_frm_orb_m1.txt and smei_frm_orb_m2.txt
	in directory $SMEIDB/cat/list. These files list the numbers
	of frames for each camera in each of three modes.
	These files are created and maintained by the IDL procedure
	smei_orbits_stat (through a daily cronjob).

	The htmd_catalogues will have names htmd_c<cam>m<mode>.txt
	where <cam> is the camera id (1,2,3) and <mode> the mode id
	<0,1,2>. The files are written to directory 'destination'.
	If /smeidb is set the destination directory is the same
	as for the smei_frm_orb_m*.txt files ($SMEIDB/cat/list).
	These catalogues are accessed by the Python script
	htmd_orbit (which in turn is used by the SMEI
	indexing daemon htmd_wait.
 MODIFICATION HISTORY:
	DEC-2005, Paul Hick (UCSD/CASS; pphick@ucsd.edu)