P60 Software Meeting
22 May 2003, CELT Conference Room

Present:  Fiona, John Henning, Brad Cenko, Roger, Marco, Derek

Fiona began by suggesting that we divide up the general software
problem into its various parts -- physical systems first, their
control systems next, and higher-level control systems last.

John then laid out the TCS design.  He discussed the various systems
that interact with the TCS:  axis drives, focus, dome azimuth,
windscreen altitude, dome shutters, flatfield lamp, and weather
station.  The TCS is responsible for the health of the telescope, and
will close the dome and stow the telescope (or refuse to open) in
dangerous conditions.  

Although the TCS allows a manual override at the operator's console,
it does not allow manual commands to mix with automatic commands.
That is, the operator at the console must "take command" of the TCS
before issuing any manual commands, and relinquish command before the
automated system will be allowed control again.  

Next, Roger and Marco discussed the camera control system, "ArcView",
which is implemented using the LABVIEW toolkit.  This is a control
system with which they are both familiar, having used it in previous
projects and configured it to their satisfaction.  The control system
for the WIRC camera at Palomar is an example of ArcView in action,
incorporating camera control, TCS communication, and rudimentary
observation planning (e.g. dither patterns and exposure sequences
associated with a single target, but not concerning itself with
multiple targets), all implemented with a network-capable (VNC) GUI
interface for the human observer (and possible remote eavesdroppers).

The customizations needed to implement the WIRC system took only one
day.  Roger and Marco are confident that they can reproduce all of the
WIRC functionality for the 60-inch, without difficulty (including
adjusting for differences in the TCS).  Also, they will control the
filter wheel as well as the camera itself.

Next, I discussed plans for the scheduling and control software.  The
scheduling software is planned, at least initially, to select the next
observation only from a list of prioritized targets that is provided
by human operators.  Thus, no global optimization of the overall
schedule, or guarantees of completeness (within a fixed time frame),
will be possible.  On the other hand, this is a straightforward coding
task that will be easy to complete.  We will also need to capability
to respond automatically to GRB alerts (GCN socket connection).  

Fiona expressed a preference for separating the scheduling function of
the control software from the Observatory Control System itself, so we
have done this.  Also, I think it is important to perform a basic
reduction on each image once it is read out to perform sanity checks
(are there stars in the image?  is the frame saturated?) and monitor
the image quality (sky level and PSF).  Finally, we discussed focusing
of the telescope.  We hope to be able to develop a good focus model,
however, the ability to execute focus runs and derive a best-focus on
the basis of observations is also desired.  John said that the TCS
will be altered to control for focus hysteresis as is currently done
at the 200-inch (TCS overshoots the requested focus by about 20
microns for inward motions, so as to always approach the desired focus
value from below).  

We then discussed improvements to the pointing model for the
telescope.  Shri has mentioned getting an improved pointing model from
Judy Cohen, however no one has looked into this yet.  John was
optimistic about the new capabilities of the pointing and tracking
system, which tracks position absolutely and is not based on the
encoders.  Since all observations will be unguided, the tracking
has the potential to limit the deepest images, especially in blue
bands, however Roger and Fiona did not find it to be a limiting factor
out to B band.  Absolute pointing is also useful, especially for the
fastest transient response.  Some testing will be necessary.  

John has sent out an email describing the proposed TCS command set.
If we want more capabilities, or care particularly about some of the
optional capabilities identified in that email, then we are to tell
John and he will see that they are implemented.  

The meeting then adjourned.  Roger has assisted me with the software
schematic that will follow this email.  Notes on the schematic:  

John Henning and Palomar are reponsible for:  TCS.  

Roger and Marco are responsible for:  GUI and Instrument Control
(ArcView modules).  

Fiona, Brad, and I are responsible for: Observatory Control,
Scheduler, Image Analysis, Pipeline, and Archiving.  Note that
Observatory Control will communicate with TCS exclusively through the
ArcView interface.