# spacepy.irbempy.find_footpoint

spacepy.irbempy.find_footpoint(ticks, loci, extMag='T01STORM', options=[1, 0, 3, 0, 0], hemi='same', alt=100, omnivals=None)

  call find_foot_point1 from irbem library and return a dictionary with values for Bmin and the GEO (cartesian) coordinates of the magnetic equator

  Parameters:
    - ticks (Ticktock class)containing time information
    - loci (Coords class)containing spatial information
    - extMag (string)optional; will choose the external magnetic field model

      possible values [‘0’, ‘MEAD’, ‘T87SHORT’, ‘T87LONG’, ‘T89’, ‘OPQUIET’, ‘OPDYN’, ‘T96’, ‘OSTA’, ‘T01QUIET’, ‘T01STORM’, ‘T05’, ‘ALEX’, ‘TS07’]

    - options (optional list or array of integers length=5)explained in Lstar
    - omni values as dictionary (optional)if not provided, will use lookup table
    - (see Lstar documentation for further explanation)
    - hemi (string)optional (valid cases are ‘same’, ‘other’, ‘north’ or ‘south’)

      will set the target hemisphere for tracing the footpoint

    - alt (numeric)optional keyword to set stop height [km] of fieldline trace (default 100km)
  Returns:
    - results (spacepy.datamodel.SpaceData)containing keys

      Bfoot - Magnitude of B-field at footpoint [nT] loci - Coords instance with GDZ coordinates of the magnetic footpoint [alt, lat, lon] Bfootvec - Components of B-field at footpoint in cartesian GEO coordinates [nT]

  See also

  `get_Lstar`, `get_Bfield`, `find_Bmirr`, `find_magequator`

  Examples

      >>> t = Ticktock(['2002-02-02T12:00:00', '2002-02-02T12:10:00'], 'ISO')
      >>> y = Coords([[3,0,0],[3,0,0]], 'GEO', 'car', use_irbem=True)
      >>> spacepy.irbempy.find_footpoint(t, y)
      {'Bfoot': array([ 47559.04643444,  47542.84688657]),
       'Bfootvec': array([[-38428.07217246,   4497.31549786, -27657.19291928],
             [-38419.08514332,   4501.45390964, -27641.14866517]]),
       'loci': Coords( [[ 99.31443778  55.71415787 -10.21888955]
       [ 99.99397026  55.70716296 -10.22797462]] ), dtype=GDZ,sph, units=['km', 'deg', 'deg']}