many delicate, micron-scale adjustments in
this system, and a magnitude 8.4 earthquake
within 100 kilometers of the telescope site
was more than sufficient to take the laser’s
alignment back to “square one.”
Figures 3.
Gemini staff operating
Gemini North from Hilo.
From here on, if you come observing at
Gemini North (e.g., for a Classical or Priority Visitor run), you can expect more air to
breathe than you would have if observing at
the summit.
We’re now working on the plan to repeat this
operation at Gemini South. In the interests
of efficiency, we’ll “copy and paste” as much
as possible from what we did in the north.
However, as this remains one of the single
biggest projects ever undertaken at Gemini
South, we don’t expect to relocate to its base
facility in La Serena until late in 2016. See the
article on Base Facility Operations starting
on page 54.
GeMS Laser and the
September Earthquake
The large earthquake that hit Cerro Pachón
in September 2015 put the complex GeMS
“sodium” laser totally out of alignment (s ee
news item below under October 2015); the
quake also caused us to lose the first of three
GeMS runs scheduled in Semester 2015B.
The GeMS laser works by generating two infrared laser beams at different wavelengths,
mixing and amplifying these in a nonlinear
crystal, and producing a signal at the sum
of the two input frequencies. The resulting
beam is then directed into beam-transfer
optics for launch onto the sky. There are
38
GeminiFocus
To fix the laser, we essentially had to start
from scratch. We adopted a systematic approach, implementing some enhancements
that will make for much quicker recovery,
especially should we suffer a recurrence
(which we all, of course, hope we will not).
By late November it became clear that we
would lose the second GeMS run; now we’re
certain that we will not be operating GeMS
in January either. We’re now focusing on
protecting the February run. Hopefully a
final concerted push will get us back to 30
Watts of light at the sodium wavelength
with the steady performance that had been
achieved before the earthquake.
Mirror Coatings North
and South
Both Gemini telescopes were shut down
for maintenance in September and October (North and South, respectively). At both
sites, a variety of maintenance tasks were
scheduled, with the biggest single task being the M1 (primary mirror) recoating at
Gemini South (Figure 4), followed by the M2
(secondary mirror) at Gemini North. Numerous preparations, documentation revisions,
and rehearsals were performed in anticipation of the Gemini South event, and the
team safely and successfully completed this
delicate and complex primary mirror coating process. Particular attention was given
to a collaborative cross-training program
with other AURA centers in Chile.
The beneficial effect of a fresh coating on
M2 is clearly seen in the GMOS-N zero points
shown in Figure 5. In Chile, the coating of the
Gemini South primary mirror was a team effort, with staff from both Gemini sites, CerroTololo-Inter-American Observatory and the
2015 Year in Review
January 2016