Contributions by Gemini staff
On the Horizon
Gemini continues its efforts to provide new and improved
instrumentation at both sites. The problems with the GMOS-South
CCDs have been solved, showing the way now for similar successful
implementation at Gemini North. Feedback from the Gemini
Instrument Feasibility draft study reports are being reviewed, and
resources for existing instrument upgrades are now committed, and
will be available soon to users with compelling ideas.
GMOS-South New CCDs: Performing Entirely to Specification
Soon after the commissioning of the new Hamamatsu CCDs in the Gemini Multi-Object
Spectrograph at Gemini South (GMOS-S) in August 2014, we noticed that when observing
in any of the binned readout modes, saturated pixels produced a decrease of counts with
respect to the bias level in neighboring pixels. This effect, known as “banding”, spanned
the entire width of the amplifier, and while it did not destroy information, it rendered data
reduction very cumbersome. Making matters worse was the saturation of a bad column on
amplifier number 5 (on CCD2, the middle one in the focal plane) that affected the entire
amplifier.
When a team of Gemini instrument scientists and engineers investigated the issue, they
identified the root cause of the problem as the Astrophysical Research Cameras (ARC) controller video boards. Representatives from ARC suggested that we try a new revision of the
video boards they now had available. After significant lab testing, we verified that these
boards would solve the problem, but required that we modify our software to be compatible with them. As of August 25th, we have fully installed and integrated these new boards
and eliminated the banding effect.
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GeminiFocus
October 2015