RE: Focus indication

[<aah@nofs.navy.mil>]

Tom,
  Focus is _not_ too hard to do, it was just a question
of why you needed the real-time diagnostic.  We have
such a diagnostic on the telescope observing code here,
but that is where a human actually sits in front of the
terminal and observes.  That person decides which star
should be used for the statistics star, getting fwhm and
magnitude after the exposure is finished.  The real-time
stuff is used to monitor how well the telescope is staying
in focus and how well the autoguider is performing.
  Then separately, in reduction, my pipeline calculates fwhmx,
fwhmy for all stars in a frame and uses that information to
adjust both the psf used for star finding and the aperture size.
However, for this pipeline processing, I find that you
have to basically determine the fwhm for all stars in the
frame and then do a median to find out what a typical
fwhm really is, since the computer doesn't know a priori
what a good star should look like.  Once you've gone to
this effort (finding a bunch of stars and measuring them),
you've already done most of the effort towards real-time
pipeline processing.
  I, for one, turn off all of the beeps when using the
Mark IV since the control system resides in a room close
to where people are trying to work.  This becomes important
during the winter when workers start at 5am and the system
continues to run for a couple of hours.  I want it to take
data automatically, and if something doesn't work, then I
just retake the data the next night.  Tom has a different
work ethic and wants to hear the beeps from overhead while
he is sleeping.  Everyone will be using these systems
differently; I just wanted to know why Tom needed quite
as many bells and whistles as he was asking for.
Arne