GeminiFocus April 2017 | Page 22

Figure 4 . The K-red filter on the left and the K-blue filter on the right . Images were obtained during the filters ’ physical inspection — with reflections of Gemini South Science Fellows
Karleyne Silva and Veronica Firpo , left to right , respectively , in bottom frame .
FLAMINGOS-2 Capabilities
Multi-Object Spectroscopy Progress
The FLAMINGOS-2 ( F-2 ) near-infrared ( NIR ) imager and spectrograph was designed with multi-object spectroscopy ( MOS ) in mind , but we could not commission this important feature until now . F-2 MOS is achieved by cutting aluminum plates (“ masks ”) with the desired slitlets ’ width , length , and target positions in the 6 x 2 arcminutes field-of-view on the sky . The masks are located on the “ MOS wheel ,” which locates each mask on the telescope ’ s focal plane and has slots for nine different masks .
One critical capability for MOS observations is the ability to change masks while the instrument is installed on the telescope . By addressing this important function ( as we did with this work ) we minimize the impact on the instrument-telescope alignment and keep the camera cryogenic dewar cold , with the detector stabilized at its working temperature of 80 Kelvin ( K ). Because F-2 is sensitive to part of the thermal region of the NIR ( up to 2.5 microns ), the masks and the instrument ’ s front section are inside a frontal cryogenic dewar . In order to exchange the MOS masks , the frontal dewar has to be thermally cycled between the ambient temperature and atmospheric pressure , and then back down to 100 K and high vacuum . The next step is to test the engineering procedures and install a batch of masks for science commissioning , planned for the week of March 27th . The next step is to test the engineering procedures and install a batch of masks for science commissioning , planned for the last week of April .
Update on K-band Filters for F-2 ( K2F2 )
In Semester 2017B , Gemini will offer in shared risk mode two medium-band filters for splitting the K-band ( 1.9 – 2.5 microns ): a K-red filter ( 2.19 – 2.44 microns ) and a K-blue filter ( 1.94 – 2.17 microns ). We have received the filters from Texas A & M University as part of the K2F2 project — a Small Project for Instrument Upgrades awarded funds in 2016 ( Figure 4 ). The filters will be installed during a scheduled instrument shutdown spanning April 6 – 18 . On-sky acceptance tests will follow , with science commissioning slated for May .
— Rubén Díaz
20 GeminiFocus April 2017