Figure 6 . Hoisting a 150-pound drive motor , using one of the largest cranes available on the island of Hawai ‘ i .
Figure 7 . The Gemini North bottom shutter ’ s broken drive box , with a segment of the drive chain showing at left . than offset by P1 ’ s much larger patrol field . Figure 5 shows the predicted sky coverage as a function of galactic latitude for the LGS + P1 configuration ( red ) compared with the conventional LGS mode ( black ).
Currently , LGS + P1 has been commissioned with the Near-InfraRed Imager and spectrometer ( NIRI ) and Near-infrared Integral Field Spectrometer ( NIFS ); it is also being offered in shared-risk mode with the Gemini Near-InfraRed Spectrometer ( GNIRS ). It is important to understand that significant flexure issues remain , which limit the use of LGS + P1 on targets that are not visible during acquisition ; this mode also significantly limits the amount of time that a target can remain in a spectroscopic slit . In fact , for spectroscopy , the Super Seeing mode requires that a continuum source be visible ( signal-to-noise ratio > 1 per spectral element ) somewhere in the science frame for typical exposure times (~ 15 minutes ). In addition , we cannot support blind offsetting at this time . Since this is a work-inprogress , part of the mode ’ s shared risk nature includes the possibility that we may not be able to implement the flexure model , or that the magnitude of flexure may be larger or more difficult to correct than expected .
Nevertheless the Super Seeing mode has proven to be very useful for conventional LGS mode programs for which the availability of guide stars was an issue ; in about 99 % of the cases , the Super Seeing mode was there to help by reducing the natural seeing PSF FWHM by at least a factor of two . — Marie Lemoine-Busserolle
Gemini North Shutdown
Gemini North had an unscheduled shutdown from August 10-31 to remedy a broken bearing in one of the drive boxes on the lower shutter ( which is also responsible for deploying the wind blind during high wind conditions ; Figures 6-7 ). This drive box failed in late July , resulting in the lower shutter being pinned in an inconveniently high position until a shutdown was possible . Favorable observing conditions near the end of 2016A allowed us to do a significant amount of 2016B observing before the semester started . This then allowed us to take advantage of a relatively light queue at this early stage in the semester and initiate an unplanned shutdown to work on the lower shutter , as well as perform work that was originally scheduled for a planned shutdown in October . That work included troubleshooting on the Acquisition and Guiding system , maintenance on the Gemini Multi- Object Spectrograph ( GMOS ), and a filter exchange on the Near-InfraRed Imager ( NIRI ). Thanks to this solution we plan to be observing on a normal schedule throughout October . A GRACES run had been scheduled during the unplanned August shutdown , but an agreement with the Canada-France-Hawai ‘ i Telescope allowed us to continue with these programs following the shutdown .
— Andy Adamson and Steve Hardash
Gemini South Shutdown
Gemini South was shut down for two working weeks from August 16-25 , to carry out annual maintenance on the Acquisition and Guidance ( A & G ) unit ( Figure 8 ) and , specifically , to address issues with the Gemini Multi-Object Spectrograph ( GMOS ) on-instrument wavefront sensor , which had become very noisy and affected our ability to guide on faint stars ( Figure 9 ). — Andy Adamson and Michiel van der Hoeven
34 GeminiFocus January 2017 | 2016 Year in Review