ing the Acquisition & Guiding (A&G) unit and
the Cassegrain Rotator. Significant work was
also done on GMOS-South to improve reliability of the mask exchange unit.
Finally, we replaced the large chiller, which
is used for the toughest cooling tasks in the
building (including the air handling units in
the dome itself ). This was a major undertaking. It required a choreographed exchange
between the existing chillers and the new
unit, which enabled the new one to run in a
test mode so that stability could be achieved
before we permanently switched the units.
The new unit appears to work very well, and,
because it is much more efficient, we expect
to realize significant savings on electricity —
a critical (and our largest) single expense.
Gemini North Operations in 2013
Figure 1.
The Gemini North
8-meter primary mirror
is inspected inside of the
coating chamber.
In 2013, the most significant change in operations that users noticed at Gemini North
was the change in Semester 2013A in the
amount of data checking performed. This
was driven by the reduction of Gemini’s budget and the need for staff astronomers and
Science Operation Specialists to use their
efforts where it has the most impact. Most
significantly, at night, the observer takes
responsibility for setting quality assurance
flags to the best of his or her ability, using a
variety of tools, including data checking programs and the environmental sensors.
During the day all band 1 data are checked
as usual, as well as any programs where a
check is deemed to be necessary by the
Queue Coordinator (up to a limit of 30 percent of the night’s data in total). Other programs, including band 4 and classical programs, are not checked, and may be left with
their quality assessment state set to “UNDEFINED”, if the nighttime observer was unable
to review them in real-time
This change represented a considerable cultural shift for Gemini staff; our dedication to
our product is strong. However, the change is
unquestionably necessary and has already produced effort savings in the north and will soon
be applied to Gemini South operations as well.
Gemini North Shutdown
An extensive planned shutdown at Gemini
North in Semester 2013B, primarily to recoat the 8-meter primary mirror, started on
September12th. The operation was completed successfully (see Figure 1). The mirror
now has unprecedented reflectivity (blue:
470 nanometers 93.0%; green: 530 nm
=
=
95.0%; red: 650 nm 95.2%; near-infrared
=
880 nm = 96.4%; thermal infrared 3300 nm
= 99.0%). Also 100% adhesion was achieved.
Senior Optical Technician Clayton Ah Hee
says Gemini should get at least as long a life
out of this coating as the last one, which lasted almost six years!
During this shutdown, the team also accomplished many other tasks, including repairing
the mirror cover and A&G unit, and performing upgrades and repairs to the instruments.
Gemini North and South Safety
Platforms
In 2013, major safety milestones were
achieved at Gemini North and South with
the installation of new, exterior Shutter Service Platforms (see Figures 2-7). These structures are designed to provide a safe means
44
GeminiFocus 2013 Year in Review
January2014