NAME:
	hide_env
 PURPOSE:
	Hides explicit directory name
 CATEGORY:
	gen/idl/toolbox/files
 CALLING SEQUENCE:
	FUNCTION hide_env, file_name, env_var=env_var, exclude=exclude, force=force, silent=silent
 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
 CALLED BY:
	CheckDir, InsituTimeSeries [1], InsituTimeSeries [2], do_file, flt_read, get_page
	grd_read, img_read, mk_flick, mpc_body, qImage, qView, qView_FileFilter
	qView_PickFiles, qsmei_sky_pick, sgp4_eph, sgp4_tle, sgp_body, skyd_cat
	skyd_version, smei_blocked, smei_buf, smei_buf_get, smei_buf_getframe
	smei_buf_gzip, smei_buf_mget, smei_buf_prep, smei_buf_read, smei_findpnt
	smei_frm_cp, smei_frm_read, smei_frm_smoothdark, smei_frm_write, smei_getfile
	smei_hdr_get, smei_hdr_make, smei_hdr_plot, smei_hdr_update, smei_last_tle
	smei_mkbase, smei_mkcal, smei_mkcal_auto, smei_mkdrives, smei_mkmask, smei_mkorb
	smei_mkorb_auto, smei_mksidereal, smei_mksky, smei_mkzldresidue
	smei_plot_timeseries, smei_rewind, smei_sgp4_orbits, smei_sky_cleanedge_map
	smei_sky_getmask, smei_sky_read, smei_sky_testcase, smei_star_cleanup
	smei_star_fit, smei_star_readpnt, smei_star_remove, smei_star_split
	smei_star_test, smei_star_writepnt, smei_www_skymaps, smei_zld_remove [1]
	smei_zld_remove [2], txt_read, vu_extract, vu_get_page, vu_header, vu_insitu
	vu_insitu_raw, vu_read, vu_select, vu_update_marker, vu_write, wso_read
	www_help_crosslinks, www_help_files, www_help_get_header, www_help_make
	www_help_section
 COMMON BLOCKS:
	common hide_env_save, nvar, env_vars, env_values
 CALLS: ***
	CheckDir, FILEPATH, InitVar, IsType, REVERSE, boost, destroyvar
 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:
	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