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CTIO Instrumentation News (1Sep95)
(from CTIO, NOAO Newsletter No. 43, September 1995)

                               4-m Imaging

More effort on improving the imaging on the 4-m telescope was spent
during the past quarter: the Shack-Hartmann image analyzer was
completed, improvements have been made to the primary mirror cooling
control, and the PFADC was collimated with respect to the primary. A
companion article presents more details and some evidence that the
cumulative effect of this program has been to improve the image
quality significantly. The next step will be to carpet the observing
floor around the telescope. This will permit the floor surface to
track the temperature of the ambient air more rapidly and thus suppress
seeing degradation caused by cold cells of air swept up off the floor
by air entering through the ventilation doors.

                            Small Telescopes

Tight budgets have made it difficult to be able to work on problems
plaguing our older, small telescopes. The MACHO program to search for
Compact Halo Objects, which makes use of these telescopes, is
providing some funds for such work. This program helped to provide
resources for the construction of a new system of radial supports for
the 0.9-m telescope which has just been installed (see accompanying
article). Another project to improve the smaller telescopes is the
installation of ventilating louvers in the dome of the 1.5-m. A
mechanical engineer has been working on the design of the system.
Fabrication is about to begin.

                                  Arcon

The development and deployment of the Arcon Array Controllers
continues to be a major activity. The Arcon system has for some time
been in use in Tucson as well as at CTIO, and its use beyond CTIO will
continue to grow to include Gemini. To help absorb the impact of these
larger demands we are fortunate to have help from the Tucson
instrumentation program: Neil Gaughan visited to help plan the effort
to build the 16-channel version of Arcon that will run the detectors
in the NOAO Mosaic Imager. Andy Rudeen of the Tucson Instrumentation
Group visited La Serena for a couple of months during which time he
collaborated in the design, with Roger Smith, of a major upgrade to
the Video card. He will also be handling PCB procurement for the Arcon
project in Tucson. We have also been able to count on the assistance
of Dee Stover of Tucson in the area of PCB layout. Finally, to aid in
the production of Arcons, we have contracted a young Chilean engineer,
Gustavo Rahmer. Meanwhile, new printed circuit versions of the VTT
(Voltage, Temperature and Telemetry) board and ADC cards, designed by
Eduardo Mondaca and Rolando Rogers respectively, are advancing
rapidly: Eduardo is testing the completed VTT and Dee Stover is doing
the artwork for the ADC.

Work also continues on the implementation of CCDs. Indeed, the
completion of the transistion from the elderly VEBs to Arcons is
nearly complete. Roger Smith has nearly completed the commissioning of
the Loral 1K chip for spectroscopy on the 1.5-m (see companion
article). Ricardo Schmidt has completed implementation of quad readout
on the STIS 2K chip for the Schmidt telescope.

                  New f/14 Secondary for 4-m Telescope

For some time, work has been going ahead on the design and fabrication
of a new secondary for the 4-m telescope which will enable us to use
f/15 instruments from the Tucson Instrumentation program (Phoenix,
COB, the Second Generation IRS, etc.) as well as our HgCdTe Imager
CIRIM and (modified) our present IR Spectrometer. The installation is
similar to that on the KPNO 4-m and uses the modified coude-feed flip
mechanism. The novel feature is that the mount will incorporate
piezoelectric actuators to define the tilt of the mirror. These will
enable the mirror to be tip-tilted to remove wavefront tilt, arising
from the atmosphere, wind-shake or high frequency tracking errors. The
mechanical fabrication of the mount has been our principal activity in
the shop this quarter and it is nearly complete. Optical fabrication
of the secondary itself has been going on in the KPNO Optical Shop.
Tests on a dummy mirror to test the tip-tilt concept mechanically will
begin shortly.

Brooke Gregory, Jack Baldwin

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