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Status of KPNO Improvement Projects (1Jun95)
(from KPNO, NOAO Newsletter No. 42, June 1995)

Preparations for major improvement projects scheduled for summer shutdown
have received the highest priority during the past quarter: thermal control of
the 4-m primary mirror and conversion of the 2.1-m to observer operation.
Mechanical conceptual design work for cooling the 4-m primary mirror is
complete and shop fabrication of the mechanical components is underway.
When installed this summer, this system will maintain a fixed, manually
selected temperature. Subsequent controller/software improvements will
ultimately enable active thermal control of the primary mirror and the
hydraulic fluid to better cope with the harsh reality of the (weather moderated)
diurnal temperature cycles. Additional activities have been sparked by the
cogent need to limit the operating expense of existing facilities through
improved reliability and reduced maintenance.

Highlights of current activity and the perceived results of recent activity
during the past quarter include:

At the 4-m, an improved seeing monitor---a "bare" COHU camera with a
narrow bandpass filter mounted at one of the viewports---has been installed.
Unlike the previous monitor, this system has no intervening optics to degrade
the inherent image quality. Readily available irrespective of the instrument in
use, the new monitor should provide a better, more uniform measure of the
delivered optical performance at the Cassegrain focus with both the optical and
the infrared secondaries---a prerequisite for monitoring the progress and
assessing the impact of the assorted seeing improvements currently underway.
The FTS observing room has been insulated to reduce heat transfer into the
dome. The underside of the mirror elevator is targeted next. Software
development for controlling the temperature of the hydraulic oil is nearly
complete.

At WIYN, KPNO personnel continued their training to support routine WIYN
operations, and have provided assistance on assorted control system, encoder,
and motor drive issues.

At the 0.9-m, the dome vents (installed last summer) and the new f/8
secondary mirror cell and support system (installed last quarter) have led to
measurable improvements in the delivered image quality. Tests are underway
to quantify this improvement and to determine optimal procedures for
balancing improvements in image quality obtained by maximizing ventilation
against degradation incurred from increased wind shake. A new dome wheel
design has been completed and fabrication is well advanced.

At the Coude Feed, last quarter's improvements to support the installation and
operation of the near-IR NICMASS camera system at the CF spectrograph
enabled three weeks of scientifically productive high spectral resolution
observations in March.

At the Burrell Schmidt Telescope, the hardware for the new CCD dewar
mount focus mechanism is nearly complete. This upgrade, which is scheduled
for installation this summer, promises to deliver more accurate, reliable, and
predictable focus.

At the McMath-Pierce Telescope and the Vacuum Telescope design upgrades
for assorted mirror mounts to provide better stability and repeatability are in
progress.

Michael Merrill

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