JULY 2019
GHOST Project Achieves Major
Milestone
During the first two weeks of July, the com-
bined Australian and Canadian GHOST teams
worked together to reach a major milestone
in Victoria, British Columbia: the integration
of subassemblies created by each organi-
zation for Gemini’s High-resolution Optical
SpecTrograph (Figure 13). The Australian
Astronomical Optics Macquarie University
team brought with them the Slit Viewer As-
sembly with electronics, as well as the Opti-
cal Fiber Cable to be connected to and tested
with the Spectrograph, which the National
Research Council Canada team had recently
assembled. A spectrum captured with this
instrument is shown in Figure 14. Software
Design Ideas, and staff from the Australian
National University, provided software sup-
port during this effort.
This work bought the fiber system, Slit View-
er Assembly, and spectrograph together for
the first time.
• An acquisition and guiding slit. Figure 13.
• A simultaneous wavelength calibration
light injection port. National Research
Council Canada team
members John Pazder,
Andre Anthony, and Scott
Macdonald (from left to
right) fit check GHOST’s
red camera optics onto
the focus stage.
The fiber system also includes two asso-
ciated devices: (1) a mode-scrambling,
noise-reducing agitator that creates vari-
able conditions for propagation of light in
all of the optical fibers; and (2) a calibrator
that is the reference source for simultane-
ous wavelength calibration via a Thorium-
Xenon lamp.
Credit: David Henderson
The Slit Viewer Assembly uses a beam splitter
to direct 99% of the slit output to the spec-
The fiber system, which sits between the
Cassegrain Unit and the Slit Viewer Assem-
bly, includes the following components:
Figure 14.
Image of
spectrum
captured from
the location
where the
GHOST blue
detector will be
positioned.
• 62 individual fibers that connect the
Cassegrain Unit to the Slit Viewer As-
sembly.
• The microlens IFU units that consist of
two low-resolution arrays and one high-
resolution array, each with a separate ar-
ray for sky.
Credit Tony
Farrell
• A flexible conduit for the optical cable
that minimizes stress on the fibers, there-
by reducing Focal-Ratio Degradation.
• Spectrograph slit optics that form a slit
from each object. The slits are 1 micro-
lens wide and either 7 or 19 microlenses
long in the standard- or high-resolution
modes, respectively.
January 2020 / 2019 Year in Review
GeminiFocus
57