rollover before it , this policy won ’ t apply to Target of Opportunity programs , for which completion rate is not in our control , or for Large and Long Programs , limited-term partner programs , or programs using visiting instruments .
‘ Alopeke Update
‘ Alopeke ( Hawaiian for “ Fox ”) arrived at Gemini North in October . It is a more sophisticated variant of DSSI , the speckle camera which has been visiting Gemini since 2012 . This new instrument occupies essentially the only spot on the telescope where it is possible to get light to it without disturbing other instrumentation — that is , in the small gap between the calibration unit ( GCAL ) and the Instrument Support Structure ( ISS ). There ’ s not much room in there , but ‘ Alopeke is small enough to fit . Therefore , although it ’ s a visiting instrument maintained and operated by a non- Gemini team , it is able to remain on the telescope at all times and thus offers much greater scheduling flexibility .
‘ Alopeke has the usual speckle capabilities — two-color simultaneous speckle imaging over a 5 arcsecond field , significantly larger than was possible with DSSI , allowing diffraction-limited imaging in the visible — but now with a wide-field mode covering 60 arcseconds with rapid ( 26 Hertz fullframe ) readout . This , of course , enables fast , two-color photometry over the larger fieldof-view and should be excellent for occultation or high-speed photometry work .
Interestingly , the early commissioning data show that the wider field may also be amenable to image reconstruction . The left image in Figure 1 shows a shows a field in the globular cluster M15 , taken in poor conditions ( 1 arcsecond seeing and very windy ). Individual exposures were just 60 milliseconds with two sets of 500 images in each filter . Integrating all of the readouts produces ,
January 2018 / 2017 Year in Review as expected , a blurry image consistent with the seeing , and with significant elongation due to windshake . From that rather uninspiring input , the team ’ s image reconstruction produces a remarkably sharp image , with 0.15 arcsecond point spread function ( Figure 1 , right ). Strictly speaking , these data are windowed , covering only the central 256 x 256 pixels ( 18.5 ”) of the 1-k square array ; however , the technique should also work over the full field .
‘ Alopeke commissioning is not quite complete at this point due to a manufacturing problem in one of the cameras . However , we expect it to figure into Gemini ’ s offerings over the coming semesters . We will post updates on its performance as this becomes clear . Interested Principal Investigators should consult the ‘ Alopeke web pages and contact Steve Howell , Principal Investigator for the Gemini Speckle program , for more details on its capabilities .
Update on Science and Evolution of Gemini Meeting
As this issue goes to press , early registration opens ( on January 4th ) for the Science and Evolution of Gemini Observatory 2018 conference . This meeting is scheduled for July 22-26 and features San Francisco ’ s historic Fisherman ’ s Wharf as a backdrop . Learn more about this exciting opportunity to be a part of Gemini ’ s future by visiting the conference website .
GeminiFocus
Figure 1 . A 19-arcsecond-wide field in globular cluster M15 , imaged in half a minute with ‘ Alopeke at 832 nm . The stacked raw frame ( left ) has seeing of approximately 1 arcsecond and significant elongation due to windshake . Point sources in the reconstructed image ( right ) have FWHM approximately 0.15 arcsecond . These commissioning data cover the central quarter of the `Alopeke field , but the technique should also be extensible to the full field .
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