NAME:
	occplot
 PURPOSE: (one line)
	Plot small pieces of stellar occultation data.
 DESCRIPTION:
	This procedure is intended to be used in plotting a very large 1-d
	vector as a function of time in which you are only interested in
	plotting a small subset of the data.  The time calibration is specified
	through the tstart and dt input parameters and the time axis is
	assumed to be strictly linear.  All time calculations are done in
	double precision to ensure the full precision of the time axis is
	saved.  Single precision gives out at the few millisecond level.

	The current plotting device is used for output.  Some attempt has
	been made to see that sensible plots come out even when using the
	!p.multi system variable to make multiple plots on a page.
 CATEGORY:
       2-D plotting
 CALLING SEQUENCE:
	occplot,data,tstart,dt,tmid,width[,yspan]
 INPUTS:
	data    - Vector containing the time-series occultation data.
	tstart  - Time, in double precision hours, of the first data point
	           or a three element vector [h,m,s]
	dt      - Time increment between points in milliseconds.
	tmid    - Mid-point of the plot in days or as a three element
	           vector [h,m,s]
	width   - Full width of the plot in seconds.
 OPTIONAL INPUT PARAMETERS:
	yspan   - yrange of the plot (centered on the mean).  If not supplied
	           the plot runs from the max to the min of the portion plotted.
	           If yspan is two-element vector, the two values are used
	           as the actual yrange on the plot.
 KEYWORD PARAMETERS:
	connect - When set, the points are connected by a line.
	over    - When set, the plot is done as an overlay on the current plot.
	psym    - Symbol to use for plot.
	title   - Title for plot
 OUTPUTS:
	Plot goes to the current graphics device.
 COMMON BLOCKS:
	None.
 SIDE EFFECTS:
	None.
 RESTRICTIONS:
	None.
 MODIFICATION HISTORY:
	12/29/92 - Written by Marc W. Buie, Lowell Observatory.  Patterned
	             after the zodiac function, 'occgraf'

	2/9/93   - Added option for yspan to allow direct specification of
	             y plotting range.  MWB

	2/10/93  - Fixed bug with top axis, axis cannot handle long or double
	             precision numbers.