Prepping and
Using GRACES
Figure 3.
Comparison of the
GRACES spectrum of
Feige 66 observed in
the two-slice mode,
and the HIRES
spectrum leveled
to match GRACES
observations
weather conditions
and resolution.
GRACES consists of three
components: (1) an injection module (Figure 4)
that sends light from the
Gemini Multi-Object Spectrograph at Gemini North
(GMOS-N) into (2) the two
long fiber cables (that connect Gemini North to CFHT,
and (3) a receiver unit responsible for injecting the
light from the fibers into
the ESPaDOnS.
First GRACES’ Science Paper
The first paper based upon GRACES data is nearing completion by Lison Malo of CFHT. Her work focuses on nearby young associations of
stars in order to better understand their formation history, determine
the initial mass function, and test theories of stellar evolution.
Her team’s work with GRACES is to establish the membership and age
of very low-mass stars and brown dwarfs in nearby kinematic groups.
Observations focus on the most probable candidates visible in the sky
in Semester 2015B that do not currently have high-resolution spectra.
Shown here is representative GRACES data of an M6 dwarf which is a
target from Malo’s research program.
It is expected that Malo’s work will be published soon in a Letter, which
will also include a description of the data reduction pipeline.
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GeminiFocus
In preparation of a GRACES observing block,
Gemini staff need to install the injection
module in GMOS-N, occupying the same
mask slot as the instrument’s integral field
unit (IFU). The injection can, like the IFU, be
moved in and out the beam, so GMOS-N imaging capability can be used for the target
acquisition.
On the CFHT side, the pick-off mirror in
the receiver unit injecting Gemini’s light in
ESPaDOnS is deployed, and the control of
the spectrograph is given over to the Gemini observer. This handover process requires
transparent communication between Gemini and CFHT at each step and has proven to
work very well.
For Gemini’s users, GRACES provides highresolution (up to R ~ 67,500) optical (400
– 1000 nm) spectroscopic capabilities with
an on-sky fiber covering 1.2 arcseconds.
Because of its unique configuration (i.e.,
the GRACES injection module replaces the
IFU module in GMOS-N, making it impossible to do both GMOS-N IFU and GRACES
observations on the same night), it is only
available for 10-night blocks, twice each
semester. Proposing for GRACES is handled
through the normal Gemini two-semester
proposal process.
2015 Year in Review
January 2016