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 .
65
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 visit-
ing instruments.
‘Alopeke Update
‘Alopeke (Hawaiian for “Fox”) arrived at
Gemini North in October. It is a more so-
phisticated 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 instru-
ment 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 larg-
er than was possible with DSSI, allowing
diffraction-limited imaging in the visible
— but now with a wide-field mode cover-
ing 60 arcseconds with rapid (26 Hertz full-
frame) readout. This, of course, enables fast,
two-color photometry over the larger field-
of-view and should be excellent for occulta-
tion or high-speed photometry work.
Interestingly, the early commissioning data
show that the wider field may also be ame-
nable to image reconstruction. The left im-
age in Figure 1 shows a shows a field in the
globular cluster M15, taken in poor condi-
tions (1 arcsecond seeing and very windy).
Individual exposures were just 60 millisec-
onds with two sets of 500 images in each fil-
ter. 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 unin-
spiring input, the team’s image reconstruc-
tion 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 com-
plete at this point due to a manufacturing
problem in one of the cameras. However,
we expect it to figure into Gemini’s offer-
ings over the coming semesters. We will
post updates on its performance as this be-
comes clear. Interested Principal Investiga-
tors should consult the ‘Alopeke web pages
and contact Steve Howell, Principal Investi-
gator for the Gemini Speckle program, for
more details on its capabilities.
Figure 1.
A 19-arcsecond-wide
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