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CTIO Instrumentation (1Mar93)
(from CTIO, NOAO Newsletter No. 33, 1 March 1993)

Further progress was made during the last three months on CTIO's
highest priority project, the new-generation array controllers. As
detailed in an accompanying article, the first of the production
controllers, Arcon 3.1, was successfully tested with a Thomson CCD on
the 0.9-m and 4-m telescopes. Work is now proceeding on the second
controller, Arcon 3.2, which will be mated to one of the Tektronix
1024 x 1024 CCDs and put into routine operation on the 0.9-m telescope
in late March. The current schedule calls for Arcon 3.3, which will
operate the Tektronix 2048 x 2048 chip, to be ready around May. The
success of the Arcon project is very important to the future of CTIO
and NOAO, and has been possible only through the dedicated and tireless
effort of the team of scientists, engineers, and programmers who have
worked on it over the past three years. During 1993, we will begin the
process of replacing the aging VEB controllers with new Arcons. Around
mid-year, work should also begin on bringing up the first infrared
detector, the NICMOS III 256 x 256 HgCdTe array, with an Arcon.

During December, another major step was taken in the effort to improve
the image quality of the 4-m telescope when the dome venting doors went
into routine operation. Although the doors had been completed several
months before, they were not put into operation until a system of
safety interlocks and barriers had been fully implemented. We would
remind observers that the 4-m catwalk is now permanently closed, and is
off-limits to all but maintenance personnel. With the implementation of
the dome doors, and the move to the ground-floor console room which
occurred several months ago, the effort to improve the thermal
environment of the 4-m dome has essentially been finished. In March, we
plan to make new measurements inside the dome with an infrared camera
in an attempt to quantify the progress that has been made.

In other areas, the first test of the 4-m Large-Format Prime Focus CCD
Camera was successfully carried out in December (see the accompanying
article by Alistair Walker for further details). A modification to
Argus was also recently completed which appears to have significantly
improved the setting accuracy of the positioners. A procedure has been
developed which allows the user to bring each of the fibers into the
center of the Argus field to establish an absolute reference point.
This can be done in 10 minutes during the day, so that no observing
time is lost. A check of the fiber positioning accuracy was made on an
astrometric field provided by Arnold Klemola of Lick Observatory.  This
test indicates that, after carrying out the new centering procedure,
nearly all of the 24 fibers can be positioned to an accuracy of 0.3
arcsec rms. As a result of this project, a few of the positioners were
found to have significant hysteresis -- work will continue to locate
and correct the source of this problem. Argus now has a full complement
of manuals which can be copied via anonymous FTP (see NOAO Newsletter
No. 32, page 17).

Mark Phillips

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