Figure 3 (Top).
Post shutdown
GeMS/GSAOI image.
Figure 4 (Bottom).
Performance results
achieved using GeMS/
GSAOI. ~75 mas in the
whole field-of-view.
The field stops are extremely difficult to
reach, as they are enclosed in a mechanical set positioned between two lenses, a
consequence of the compact design of the
Canopus optical bench. Rather than adjust
the field stops, the other option we identified was to realign the CCD behind each
LGSWFS and the calibration source. Doing
this, we realized, would restore alignment
to the calibration source, the field stops,
and the CCDs.
We proceeded with this option because (1)
it was the least invasive, and (2) the LGSWFS
CCDs were the easiest elements to move.
We then remounted Canopus on the telescope and waited for the telescope shutdown to end.
During the first post shutdown
GeMS observing run (September 2014), we confirmed that the
realignment of the CCDs had indeed removed the elongation issue (Figure 3). Since then, several
successful science runs with the
system have produced excellent
results. Figure 4 illustrates the level of performance that the system
can now provide.
Future Plans for GeMS
A New Natural Guide
Star WFS System
The AO team at Gemini, with collaborators from the Australian
National University, is currently
working on upgrading the Natural Guide Star Wave Front Sensor
(NGSWFS) system (see page 30 for
an update). This upgrade will allow
the system to use natural guide
stars as faint as magnitude 17.5 —
a gain of about two magnitudes
over the current NGSWFS. This
gain will increase AO sky coverage
by a huge margin, while opening
up many extragalactic science opportunities; up to 50 percent of
the sky around the Galactic poles
would be available with at least
one guide star.
48
GeminiFocus
2015 Year in Review
January 2016