NAME:
  slewdur
 PURPOSE:
  Estimate the time to slew the telescope from one location to another.
 DESCRIPTION:
 CATEGORY:
  Data Acquisition
 CALLING SEQUENCE:
  ans=slewdur(jd,ra0,dec0,ra1,dec1)
 INPUTS:
  jd   - Julian date at time of slew
  ra0  - Right ascension of starting point
  dec0 - Declination of starting point
  ra1  - Right ascension of destination
  dec1 - Declination of destination
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
 OUTPUTS:
  return value is estimated time to complete a slew over the requested
    distance (time is in seconds).
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  Written by Marc W. Buie, Lowell Observatory, 2002/01/27