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# Directory Listing of Routines

# general/cotrans/aacgm

- AACGM_PLOT
- AACGMIDL
  This library is a pure IDL version of the AACGM library
- EQN_OF_TIME
  equation of time for a given longitude and year
- SOLAR_LOC
  location of the sun for given year and time
- CNV_AACGM
  convert to and from AACGM and Geographic coordinates
- CALC_MLT
  calculate magnetic local time for a given longitude
- LOAD_COEF
  load a set of AACGM coefficients
- CNV_MDHMS_SEC[1]
  convert time from the form year, month, day, hour, minute, sec
- CNVTIME[1]
  This provides an alternate entry point to CNV_MDHMS_SEC
- CNV_SEC_MDHMS[1]
  Convert the time in seconds of the year to the form month, day

# Routine Descriptions

## AACGMIDL

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     NAME:
    	AACGMIDL

     PURPOSE:
    	This library is a pure IDL version of the AACGM library

     ROUTINES:

    	EQN_OF_TIME     equation of time
    	SOLAR_LOC 	find location of sun
    	CNV_AACGM	convert coordinates to/from magnetic/geographic
    	CALC_MLT	calculate magnetic local time
    	LOAD_COEF	load a set of AACGM coefficients

(See general/cotrans/aacgm/aacgmidl.pro)

## AACGM_PLOT

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    Procedure: AACGM_PLOT

    Description:  Parameterized aacgm coordinate plotting routine. Run the routine with the appropriate coordinates
                  and it will plot a grid representing corrected geomagnetic coordinates in magnetic local time.  If
                  you provide no local time, this routine will assume a local time of 2008-01-01/00:00:00 UT

                  Based upon aacgm_example of Eric Donovan @ U. Calgary
                  This routine uses AACGM code written by R.J. Barnes,Kile Baker, and Simon Wing.  Their AACGM code was
                  modified slightly for use in the themis distribution.

    Keywords(All input lats/lons are in degrees):

     lat_center:   The latitudinal center of the projection that you want to plot.(Default: 62)
     lon_center:   The longitudinal center of the projection that you want to plot.(Default: 256)
     map_scale:  Set the scale of the map presented. This is the same as the map scale argument to
                 other idl mapping routines. (Default: 42e6)
     height:  The height at which coordinates should be plotted.  Note that coordinates may not be
              calculable at low heights when plotting near the equator.(Default: 110)
     local_time: The time in UT that should be assumed for MLT(default: '2008-01-01/00:00:00' UT)
     lat_range:  A two element array that represents the maximum and minimum latitude
                 that should be calculated.  Smaller ranges speed up calculations.(Default: [50,70])
     lon_range:  A two element array that represents the maximum and minimum longitude
                 that should be calculated(in local magnetic coords) Smaller ranges speed up
                 calculations. (Default: [0,360])
     lat_step:  The size of latitudinal steps between lines. (Default:5)
     lon_step:  The size of longitudinal steps between lines. (Default:15)
     lab_step:  The number of N-S lines between labels (Default: 6)
     n_lat_pts: The number of points per globe to use when drawing E-W lines. (Default: 360)
     n_lon_pts: The number of points per globe to use when drawing N-S lines. (Default: 180)
     lab_pos:  The argument controls the position of the labels in the N-S direction
               0: Draws the labels at the closest latitude to the equator(Default)
               1: Draws the labels at the maximum latitude in the range.
               -1: Draws the labels at the minimum latitude in the range
      projection:  The type of projection as a string.  Default is 'orthographic', but you can select any
               of the projections that are usually available to the map set routine. To see a list
               of available projections type: 'MAP_PROJ_INFO, PROJ_NAMES=names & print,names'

     You can also pass in any keywords that the plot command or the map_set command take.  These can be useful for
     things like controlling line thickness when exporting graphics.

     Notes:
     1. This routine loads the AACGM coefficients for the current time period( 2005-2010)  If
        this routine is being used for times outside this period, features need to be added to
        utilize the aacgmidl routines that load other coordinate sets.

     2. If you can think of any features that might ease usability please feel free to contact us.

     $LastChangedBy: pcruce $
     $LastChangedDate: 2008-09-18 15:48:50 -0700 (Thu, 18 Sep 2008) $
     $LastChangedRevision: 3517 $
     $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/spdsoft/trunk/general/cotrans/aacgm/aacgm_plot.pro $

(See general/cotrans/aacgm/aacgm_plot.pro)

## CALC_MLT

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     NAME:
           CALC_MLT

     PURPOSE:
           calculate magnetic local time for a given longitude

     Calling sequence:
    	mlt=CALC_MLT(yr,t0,mlong)
    	    t1 is the seconds from the start of year and
               mlong is the magnetic longitude of the observing
               point.

(See general/cotrans/aacgm/aacgmidl.pro)

## CNVTIME[1]

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     NAME:
    	CNVTIME

     PURPOSE:
     	This provides an alternate entry point to CNV_MDHMS_SEC

(See general/cotrans/aacgm/cnvtime.pro)

## CNV_AACGM

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     NAME:
           CNV_AACGM

     PURPOSE:
           convert to and from AACGM and Geographic coordinates

     Calling sequence:
    	CNV_AACGM,in_lat,in_lon,height,out_lat,out_lon,r,error
    	   the calculated latitude and longitude for the
              given height are returned in out_lat,out_lon.

(See general/cotrans/aacgm/aacgmidl.pro)

## CNV_MDHMS_SEC[1]

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     NAME:
           CNV_MDHMS_SEC

     PURPOSE:
           convert time from the form year, month, day, hour, minute, sec
           to seconds of the year

     Calling sequence:
    	t = cnv_mdhms_sec(yr, month, day, hour, minute, sec)
    	   if the arguments are arrays, they must be the same size

    	   OR

    	t = cnv_mdhms_sec(time_array)
    	   where time_array is a 2-d intarr (6,n)
    	   the first dimension gives the year, month, day, hour, minute, sec

(See general/cotrans/aacgm/cnvtime.pro)

## CNV_SEC_MDHMS[1]

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     NAME:
    	CNV_SEC_MDHMS

     PURPOSE:
    	Convert the time in seconds of the year to the form month, day
    	hour, minutes, and seconds

     CALLING SEQUENCE:
    	status = cnv_sec_mdhms(yr, mo, day, hour, minute, sec, yr_secs)

    	All the arguments must be given. yr must be assigned a value (this
    	determines whether you are in  aleap year or not).  Mo, day, hour,
    	minute and sec must be declared to be normal integers and yr_secs
    	must be given a value and must be a long integer.

    	The status will be 0 for success and -1 for failure

(See general/cotrans/aacgm/cnvtime.pro)

## EQN_OF_TIME

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     NAME:
           EQN_OF_TIME

     PURPOSE:
           equation of time for a given longitude and year

     Calling sequence:
    	eqt = eqn_of_time(mean_lon,yr)

(See general/cotrans/aacgm/aacgmidl.pro)

## LOAD_COEF

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     NAME:
           LOAD_COEF

     PURPOSE:
           load a set of AACGM coefficients

     Calling sequence:
    	load_coef,fname
    	    fname is the filename.

(See general/cotrans/aacgm/aacgmidl.pro)

## SOLAR_LOC

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     NAME:
           SOLAR_LOC

     PURPOSE:
           location of the sun for given year and time

     Calling sequence:
    	solar_loc,yr,t1,mean_lon,dec
    	   t1 is the seconds from the start of year.
              the mean longitude and declination are returned
              in mean_lon and dec as floats.

(See general/cotrans/aacgm/aacgmidl.pro)