The three-color map
shown in Figure 5 reveals
Jupiter’s weather layer
near 8.6 microns, where
temperature, cloud opac-
ity, and gaseous species
(like deuterated methane and phosphine)
govern Jupiter’s spectrum. The researchers
constructed the map from spectral scans
over two nights (March 12–13, 2017), and it
represents close to the highest spatial resolu-
tion ever achieved by the TEXES instrument.
At mid-infrared wavelengths most of the
seeing is due to image motion, which Gem-
ini’s rapid tip-tilt secondary mirror removes.
The result is diffraction-limited images with
0.3 arcsecond resolution without the use
of adaptive optics. This easily surpasses the
spatial resolution afforded by past spacecraft
flybys of Jupiter (Voyager and Cassini) in the
mid-infrared wavelength range.
A high-resolution spectrum was measured
for every pixel in this map. The essential in-
formation from the spectra is shown in the
false color image: deep, warm temperatures
at the cloud tops (red); cooler temperatures
at higher altitudes near the tropopause
(blue); and an intermediate altitude (green).
The Equatorial Zone and the Great Red Spot
at the bottom right are cold and dark at all
three wavelengths. The turbulent wake seen
to the west (left) of the Great Red Spot is
darker (cooler) and distinct from the rest of
Jupiter’s South Equatorial Belt (SEB). An out-
break of dark, cold, and cloudy plumes can
be seen in the SEB near 15˚ south, 270˚ west.
Finally, the pattern of cold, cloudy plumes
(dark) and warm, bright hotspots (white)
can be seen encircling the planet near lati-
tude 7˚ north, on the edge of Jupiter’s North
Equatorial Belt. These data will be used to
determine the 3D temperature, aerosol, and
gaseous structure to support Juno’s close-in
observations of the giant planet.
April 2017
GMOS-N CCD Upgrade Update
The Gemini-North Multi-Object Spectro-
graph (GMOS-N) is currently being upgrad-
ed with a new detector array (Figure 6),
consisting of three CCDs manufactured by
Hamamatsu Photonics. During February, the
commissioning team successfully installed
and aligned the new array in the Gemini
North lab. In early March, following the CCD
installation, GMOS-N was mounted back on
the telescope, where it passed the first light
milestone during on-sky nighttime commis-
sioning observations.
We expect the new Hamamatsu CCDs to
show improved red sensitivity compared to
the previous GMOS-N e2v deep depletion
detectors. The new detectors are similar to
those previously installed in GMOS-S. Fur-
ther information and updates are available
on the Gemini North night log summary
pages; watch for updates in our monthly e-
newscast and on the instrument availability
webpage. The update of the data reduction
package is ongoing, while the detector array
is being characterized. We estimate that the
full data reduction package will be available
in a couple of months.
First data with the new
detector array have
been obtained since
March 26, 2017.
GeminiFocus
Figure 5.
Combination of three
TEXES spectral scans,
with red through blue,
corresponding to
increasing altitude above
Jupiter’s cloud tops. Note
the cool wake to the left
of the Great Red Spot seen
at lower right (about 15˚
west longitude and -20˚
Latitude).
Credit: L. Fletcher,
University of Leicester, UK
Figure 6.
The new GMOS-N
detector array showing
the three new CCDs,
which consists of
two different types
of detectors: the two
outer detectors (left and
right) have an improved
red and blue response
compared to the middle
detector.
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