NAME:
  datamon

 PURPOSE:
  Summary plot of raw data contained in photometry log file

 DESCRIPTION:
  This program plots photometry data from files in the format written by
    RDPHALT.  These files usually contain extracted photometry from a single
    night's observations.  There are four plots generated by this program.

    (1) Instrumental magnitude versus time.  This plots all objects and all
        filters on the same plot.  For some types of data this plot can be
        quite confusing.  For some datasets, this can show overall trends in
        data quality.  Because of the scaling this plot usually only shows
        the most glaring problems.

    (2) Shifted instrumental magnitude versus time.  The first object and the
        first filter is (arbitrarily) chosen as the "reference".  All other
        object/filter combinations are shifted to have the same mean as the
        reference.  The magnitude shown is of little importance but you can
        see much more subtle trends in the data because the scaling doesn't
        crunch things down as much.  Good data will show only variations
        caused by airmass though these may not be readily discernable depending
        on the data collection pattern.

    (3) FWHM versus time.  All objects and all filters are plotted.  The FWHM
        is the number directly from the file with no scaling or conversions.
        Most of the time this value should be in arc seconds but there is
        nothing present to allow the program to know.  It's up to you to know
        what the absolute number means.  Superimposed on the plot are solid
        curves, one for each filter that shows the trend for that filter over
        time.  The curve is labeled with the name of the filter as read from
        the log file.

    (4) Sky signal versus time.  The sky signal from each observation is
        plotted in photons/second.  The conversion to photons is done by using
        the gain value listed in the log file.  Similar to the previous plot,
        lines are superimposed to highlight the trends for each filter.

  By default, the plots are sent to the current plotting device. This would
    normally be the display.  When using the default plotting device, the
    plots are sent to four windows (or pages).  Only the first plot is
    identified by the file name being plotted.

  If you use the /PRINT option, the plot is generated for one page and sent
    to the default printer.  The contents of the plots are the same except
    for being formatted to fit all on one page.

 CATEGORY:
  Photometry

 CALLING SEQUENCE:
  datamon,file

 INPUTS:
  file - String of photometry log file to read and plot.

 OPTIONAL INPUT PARAMETERS:

 KEYWORD INPUT PARAMETERS:
  PRINT - Flag, if set generates a plot to printer.
  QUEUE - String, name of print queue to send plot to.  (overrides current
             default printer, unix only).
  NOQUEUE - Flag, if set suppresses sending the plot to the printer (is
             only 

 OUTPUTS:

 KEYWORD OUTPUT PARAMETERS:

 COMMON BLOCKS:

 SIDE EFFECTS:

 RESTRICTIONS:

 PROCEDURE:

 MODIFICATION HISTORY:
  Written by Marc W. Buie, Lowell Observatory, 2000/07/14.
  2000/10/09, MWB, fixed sky plot bug, added lowess curves to sky
  2001/04/18, MWB, changed systime call to use /julian flag