~ 500 to 1000 times per second. The result is
about a 20-fold increase in the area of the observed patch of sky compared to previous AO
systems, while providing uniform corrections
over the entire field from edge-to-edge.
GeMS is a facility instrument, and as such it
can direct its light output to different science
instruments installed at the Cassegrain focus
of the Gemini South telescope. The main instrument used to date is GSAOI, a wide-field
camera designed to work at the diffraction
limit of the 8-meter telescope in the nearinfrared (NIR).
Science Verification:
A Long-awaited Milestone
In August 2012, the GeMS/GSAOI team released a call for System Verification (SV) targets, offering a total observing time of 60
hours for a wide range of science topics. The
SV programs provide an end-to-end test of
a new instrument or capability, from the
proposal process to data delivery, prior to
offering it to the community for general use.
With GeMS/GSAOI, one main objective was
to demonstrate the gain brought by MCAO
on a large variety of science topics, including extended sources, crowded fields, and
faint targets. We received great feedback,
with 23 programs submitted for a total of
138 hours, from which 13 were selected for
execution between November 2012 and
January 2013.
The SV period did not start as expected: In
early November, the power produced by
the sodium laser fell to a level one-half of
what it was a few weeks before, preventing
the team from completing the remaining
commissioning tasks. With the assistance
of Zach Prezkuta (a laser engineer from
Lockheed Martin Coherent Technologies),
Gemini laser specialist Vincent Fesquet,
worked non-stop for three weeks to recover the laser light to a nominal 50 watts (W)
— in time for a run in December (Figure 1).
Atmospheric seeing and laser conditions
were excellent during this period. The team
overcame most of the delays accumulated
during commissioning, and SV observations
started before month’s end.
Figure 2.
A three-pointing
GeMS/GSAOI image
of the Orion Nebula’s
Bullets field.
Orion Bullets:
A Dramatic Demonstration
The team selected the Orion Bullets as their
first SV target (Figure 2). These wake-like features in the Orion Nebula are clumps of gas
violently ejected from an unknown event
associated with the recent formation of a
cluster of massive stars. The strong winds
produced by this “explosion” expelled these
bullets of gas at supersonic speeds, leaving
behind the distinctive tubular and coneshaped wakes we now see; the wakes shine
like tracers due to the bullets piercing and
January2014 2013 Year in Review
GeminiFocus
39