to the starting position). After the telescope
shutdown, we fully checked and released
the instrument for operation again.
Gemini South Shutdown
Completed
Gemini South completed its annual tele-
scope shutdown on August 31st. Some addi-
tional mechanical support staff from the Na-
tional Optical Astronomy Observatory joined
in — an example of sharing resources, which
we expect to continue. The shutdown’s main
objective was to carry out preventive mainte-
nance on the acquisition and guidance unit
(A&G; Figure 11). Excellent teamwork and
cross-training ensured this system is ready
for another year’s observations. Apart from
the regular maintenance, an encoder on the
science fold linear stage mechanism was re-
placed, restoring redundancy and skew de-
tection functionality. After working in the lab
to prepare the spare cable wrap motors, we
replaced both motors for the elevation wrap,
since one of them was drawing high currents.
This marks the conclusion of an important
task within our reliability program.
Figure 11.
Performing
maintenance on
the Science Fold
mechanisms in one slice
of the A&G unit.
Credit: Joe D‘Amato
On Saturday August 18th, a full facility shut-
down was required in order to install new ca-
bling to the uninterruptible power supplies.
Some time ago these units (feeding the data
center among other things) were replaced
with higher capacity ones, but the cabling
prevented their use at full capacity. A small
portable generator provided emergency
power for some lighting at the work loca-
tions. The data center was switched off and
all instruments powered down and started
to warm up. We completed all the work in
one day; the data center was brought back
up, and the instruments recovered. Net re-
sult: we reduced both the number of poten-
tial points of failure and the overall cost of
maintenance.
Other issues addressed in this shutdown
were the installation of improved encoder
mounts on the elevation axis, checks on
valves within the hydrostatic bearing sys-
tem, and leak checking on the Cassegrain
wrap Helium lines (one leak was found, and
we swapped that line to a backup).
On Friday August 31st, all systems were
handed back for observing; although bad
weather wiped out the first night while the
team was having a shutdown party. All sys-
tems were found in perfect working order,
and all the instruments checked out (includ-
ing GMOS after the bubble fix); the telescope
is now ready for another year of operation.
Every year, these shutdowns become more
efficient and streamlined. Careful planning
and attention to procedures and risk assess-
ments are paying off in making this more
and more a routine operation. A big thanks
to all involved in making this a success!
Gemini North Shutdown
Underway
Gemini North commenced its annual shut-
down on Monday, September 17th. Work
is progressing on several systems, includ-
ing A&G issue follow-up and maintenance,
Gemini Near-InfraRed Spectrometer cold-
head refurbishment and other maintenance,
GMOS VME hardware work, Near-InfraRed
Imager and spectrometer Detector Control-
ler troubleshooting, and Primary Mirror Con-
62
GeminiFocus
January 2019 / 2018 Year in Review