NAME: 
  rdobscod
 PURPOSE:
  Read standard observatory code data file.
 DESCRIPTION:
 CATEGORY:
  File I/O
 CALLING SEQUENCE:
  rdobscod,code,lon,rhosinp,rhocosp,obsname,valid
 INPUTS:
 OPTIONAL INPUT PARAMETERS:
  FILE - Name of observatory code file to read.  Default=obscode.dat
 KEYWORD INPUT PARAMETERS:
 OUTPUTS:
  code    - array of observatory codes
  lon     - longitude of observatory (degrees)
  rhosinp - rho * sin(co-lat)
  rhocopp - rho * cos(co-lat)
  obsname - Name of observatory
  valid - Flag, true if the file was found and read properly.
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  2000/11/19, MWB, added different default file for Windows.
  2001/03/12, MWB, changed method of locating the obscode.dat file.  Now
                 looks in the user's IDL_PATH for this file.
  2002/09/09, MWB, added support for string obscode values
  2005/11/28, MWB, format of obscode.dat changed, fixed format for reading.