1 Director’s Message 45 On the Horizon Markus Kissler-Patig Gemini sta! contributions 3 Gemini South Explores the 55 A Transition Comes to an End Growth of Massive Galaxy Clusters Inger Jørgensen Sarah Sweet, Rodrigo Carrasco, and 59 Gemini Harnesses the Sun from Fernanda Urrutia Both Hemispheres 7 A Gemini Spectrum of a World Alexis Ann Acohido Colder than a Night on Maunakea Gemini Connections Andy Skemer 61 Peter Michaud 11 A Case of Warped Space: Confirming Strong Gravitational 64 A New Look for Gemini’s Legacy Lenses Found in the Dark Energy Images Survey 66 Observatory Careers: New Brian Nord and Elizabeth Buckley-Geer Resources for Students, Teachers, and Parents 16 Dusting the Universe with Supernovae 68 Journey Through the Universe: Jennifer Andrews Twelve Years, and Counting! Alexis-Ann Acohido 20 Science Highlights Gemini sta! contributions 71 Viaje al Universo 2016: Empowering Students with Science News for Users 31 Maunel Paredes Gemini sta! contributions

ON THE COVER: GeminiFocus Color composite image January 2017 / 2016 Year in Review of the galaxy cluster GeminiFocus is a quarterly publication SPT-CL J0546-5345, of the Gemini Observatory comprised of Gemini 670 N. A‘ohoku Place, Hilo, Hawai‘i 96720, USA GeMS/GSAOI and HST Phone: (808) 974-2500 Fax: (808) 974-2589 data. White inset at right bottom shows Online viewing address: www.gemini.edu/geminifocus Gemini Ks image of the region. The article on Managing Editor: Peter Michaud this work begins on Associate Editor: Stephen James O’Meara page 3. Also shown Designer: Eve Furchgott/Blue Heron Multimedia are the covers from Any opinions, findings, and conclusions or April, July, and October recommendations expressed in this material are those of issues of GeminiFocus. the author(s), and do not necessarily reflect the views of the National Science Foundation or the Gemini Partnership.

ii GeminiFocus January 2017 | 2016 Year in Review Markus Kissler-Patig

Director’s Message Gemini Brings 2016 to a Successful Close

Gemini is looking back at the rapid passing of a another successful year — the !rst full one after the transition to operating the Observatory on a 25% reduced budget, which translates to ~25% less sta". Of course a few things are moving forward more slowly, but, overall, the Ob- servatory is as productive as ever and continues to operate smoothly. In fact, we have intro- duced several new and innovative ideas into our operations and instrumentation programs, as described in the following overview. With December comes the end of the !rst full year of Base Facility Operations at Gemini North — that’s a full year without nighttime sta" at the telescope on Maunakea. Both our telescope operators and observers have been enjoying the increased oxygen in Hilo, and we have not seen any negative impact on our technical downtime. To the contrary, from the control room in Hilo the team operating the Di"erential Speckle Survey Instrument (DSSI) established a new record this past January for the number of targets (>130) observed in a single night! The !rst night of Base Facility Operations at Gemini South began on November 14th, as de- scribed in this issue’s News for Users for January 2017. We still retain the option of observing from Cerro Pachón or Maunakea — especially in instances where a visitor instrument requires it — but we anticipate that summit observers will be rare in the future. 2016 was also the !rst full year of Fast Turnaround programs, which o"er researchers in the Gemini community 10% of the time on both telescopes every month; participants typically obtain their data as quickly as six weeks after applying for time. Additionally, the Subaru com- munity joined this Gemini program in May in exchange for time on the Subaru telescope. We continue to improve the Fast Turnaround schemes and will gradually o"er all modes and all instruments in the regular Call for Proposals.

January 2017 | 2016 Year in Review GeminiFocus 1 In 2016 we saw a surge of contacts from Prin- international publications. And as has be- cipal Investigators o"ering potential visitor come custom over the past few years, Gemini instruments. Consequently, we now have made a strong presence at the recent Society over 10 instruments in the queue to exploit of Women Engineers meeting, joining forces Gemini’s state-of-the-art telescope facilities. with all the other AURA centers in a large The Observatory continues to invite inquiries booth to promote engineering positions at from all instrument teams that would like to the observatories. bring their instruments to our telescopes. Yes, looking back, 2016 was a very success- Over the past 12 months we have welcomed ful, productive, and innovative year, and 2017 back some old friends — including DSSI, Texas promises to be exciting as well — with both Echelon Cross Echelle Spectrograph (TEXES), telescopes fully functional in remote opera- Phoenix, and Gemini Remote Access to CFHT tion mode, more visitor instruments in the ESPaDOnS Spectrograph (GRACES) — all of- queue, and progress being made in upgrades fered in the regular Call for Proposals, as well to our facility instruments (e.g., the multi- as some newcomers (e.g., the hyper-precision object spectroscopy mode of FLAMINGOS-2). polarimeter POLISH 2, which visited in No- Also signi!cant, we have procured a new laser vember). We also had groups projecting into for Gemini South (and are in the procurement the future, such as the Immersion GRating IN- process for Gemini North); Gemini is rapidly frared Spectrograph (IGRINS) team, from the moving towards making laser adaptive optics University of Texas Austin, that obtained ~ 130 a true part of our queue operations, rather hours of observations for 2018A through the than it being restricted to a block schedule. latest round of Large and Long programs; we Stay tuned, because surely, in 2017, we will are looking forward to supporting the IGRINS continue Exploring the Universe, Sharing its team and o"ering this great instrument to the Wonders! rest of the Gemini community in about a year. Internally, 2016 was an equally important year, as AURA was awarded a new six-year coopera- Markus Kissler-Patig is the Gemini Observatory tive agreement to manage the Gemini Obser- Director. He can be reached at: vatory — after a long recompetition process [email protected] launched by the National Science Foundation at the end of 2014. We can now work closely with the Large Synoptic Survey Telescope project and with the National Optical Astrono- my Observatory to streamline and coordinate our operations in Chile (and beyond). Gemini’s public education and outreach re- mained vibrant throughout the year, host- ing its 12th and 6th editions of our #agship programs Journey Through the Universe in Hawai‘i and Viaje al Universo in Chile, respec- tively. These programs paralleled Gemini’s many other outreach activities, including the dissemination of numerous press releases that made front page news in national and

2 GeminiFocus January 2017 | 2016 Year in Review January 2017 Sarah Sweet, Rodrigo Carrasco, and Fernanda Urrutia

Gemini South Explores the Growth of Massive Galaxy Clusters Using high-angular-resolution images obtained at Gemini South, we have measured, for the !rst time, the stellar mass–size relation for 49 galaxies in a cluster environment at redshift z ~ 1. Our data suggest that the most likely relationship between stellar mass and size has a constant slope over time. This !nding leads us to conclude that the probable evolutionary course for the most massive spheroid-like galaxies since z ~ 1 is either from minor mergers (i.e., when a galaxy grows via accretion of small satellite galaxies), or adiabatic processes (such as out"ows from active galactic nuclei), or a combination of both.

The Evolution of Massive Galaxies Over Cosmic Time During the past 20 years astronomers have developed a picture for the evolution of the size and structure of galaxies — from the formation of the !rst galaxies in the early Universe, to what we see today. One of the most important discoveries in the last decade is that the most 11 massive spheroid-like galaxies (i.e., galaxies with masses > 10 MSun) in the distant Universe (z > 1) are much smaller in physical size than those with the same stellar mass in the local Universe; the e"ective radii of these massive galaxies at z ~ 1- 4 are observed to be, on aver- age, a factor of 2-6 times more compact when compared with local systems with the same stellar mass. At z = 0, massive compact galaxies are very rare; only a few have been found to date. Presumably, the most massive high-redshift galaxies must evolve signi!cantly in size to become present-day passive elliptical galaxies.

January 2017 | 2016 Year in Review GeminiFocus 3 Figure 1. One important open question remains. It wavelengths longer than the 400 nanometer False-color image of concerns how these galaxies grew in size spectral break to restrict the observations to SPT-CL J0546–5345 at and what main physical mechanism(s) are galaxies dominated by the light of the un- z = 1.067. Gemini involved. Mergers of galaxies with similar derlying old stellar population. The accuracy GeMS/GSAOI K (this s stellar masses (major mergers), accretion of of the stellar mass–size relation is also im- work) = red, HST ACS small satellite galaxies (minor mergers), and proved as the number of galaxies observed F814W = green, HST ACS F606W = blue. The rapid mass loss caused by active galactic nu- increases. Previous high-angular-resolution red polygon shows clei (AGN) or supernova winds (adiabatic ex- images obtained from the ground are lim- the approximate sky pansion) could all contribute to the dramatic ited by the small e!ective "eld-of-view of coverage of the GSAOI growth in the size of these galaxies. We can the instruments used for the observations. pointings. PSF stars distinguish between these physical mecha- Given the large "eld-of-view provided by are indicated by white nisms by comparing the slope of the stellar the Gemini Multi-conjugate adaptive optics circles. The star near the top of the image mass–size relation of the massive high-red- System, combined with the Gemini South with two circles is a shift galaxies with the local sample. Adaptive Optics Imager (GeMS/GSAOI), we binary star. The inset at avoid this problem by simultaneously ob- Accurate determination of the stellar mass– lower left is a zoom-in serving several galaxies in a single "eld. of the cluster core. size relation depends most strongly on the The scale bars in the resolution of the images, the rest-frame inset and full image wavelength of the observations, and the A High-angular-resolution show the angular and number of galaxies observed. Superb resolu- View of Cluster Galaxies at z ~ 1 physical projected tion is required to accurately measure the ef- distances at the cluster We used GeMS/GSAOI, the world’s most ad- fective radius for the most compact galaxies redshift. The red, green, vanced adaptive optics system, to image at z > 1. We need rest-frame observations at and blue galaxies in the cluster SPT-CL J0546- spots on the 5345 at redshift z = 1.067. This cluster, scale bar detected as part of the 2,500 square in the inset show the degree South Pole Telescope Sunyaev- PSF FWHM Zel’dovich survey (Brodwin, Mark, et al., for each ApJ, 721: 90, 2011), is a massive cluster band. North 15 with a virial mass of 10 MSun and several is up and compact massive spheroid-like galaxies east is left. at its center. We imaged the galaxies us-

ing the Ks "lter at 2.2 microns. The "nal combined image presents a variation of the Point Spread Function (PSF) Full- Width Half-Maximum (FWHM) between 80-130 milliarcseconds (mas) within the GSAOI 85” x 85” "eld-of-view (Figure 1) — translating to a physical size be- tween 0.66-1.07 kiloparsecs (kpc) with- in a "eld-of-view of 697 kpc2 (1” = 8.2 kpc at the cluster’s rest frame). The PSF FWHM achieved with GeMS/GSAOI is, on average, a factor of 1.5 better than the angular resolution provided by the

H160 "lter of the Hubble Space Telescope (HST) Wide-Field Camera 3, which has a

4 GeminiFocus January 2017 | 2016 Year in Review PSF FWHM of 180 mas, and is comparable to that of the HST Advanced Camera for Sur- veys’ F814W (I-band) !lter (Figure 2).

The Stellar Mass–Size Relation at z = 1

An accurate calculation of the stellar mass– size relation requires a robust determination of the stellar mass and physical size of the galaxies. We estimated the stellar mass for mergers were a dominant source of the evo- Figure 2. 49 of the SPT-CL J0546–5345 cluster mem- lution in the stellar mass–size relation, then The core of the SPT-CL ber galaxies using public codes. We then !t the most massive galaxies would experience J0546-5345 galaxy publicly available stellar population synthe- the most rapid growth; the slope of the stel- cluster at z = 1.067. sis models (used as tools for interpreting the Left: GeMS GSAOI K lar mass–size relation would then be steeper s image. Right: HST ACS integrated light of galaxies) to the derived in the local Universe than at z = 1 — an e"ect photometry assuming a certain Initial Mass F814W image. The we do not see in our results. scale bar at the lower Function (which describes how mass is ini- left shows the angular tially distributed within a stellar population). Figure 3 also shows the stellar mass-size rela- tion for the cluster SPT-CL J0546-5345 com- and physical projected distance at the cluster We selected galaxies with ages older than 10 pared with other work in the literature. Our giga-years and younger than the age of the redshift. North is up and results emphasize the importance of high- east is left. Universe (details can be found in the article resolution observations at the rest-frame accepted for publication; see end of article). wavelength of the cluster galaxies. Observa- We used the publicly available code GAL- tions at shorter wavelengths — i.e., at the B- FIT (Peng, C. Y., et al., AJ, 139: 2097, 2010) to band and U-band rest frame (top-right plot measure the circularized e"ective radius, de- in Figure 3) — show a shallower slope and !ned as r = ab, where a and b are the e"ec- e larger scatter in radius, due to ultraviolet- tive semimajor and semiminor axis, respec- bright star-forming knots. In addition, the ef- tively, as a measurement of the physical size fect of resolution (bottom right plot in Figure of the galaxies. The K -band stellar mass–size s 3) can lead to misinterpretation of the true relation for the SPT-CL J0546-05345 cluster physical mechanism involved in the extraor- member galaxies at z = 1 and SDSS galaxies dinary growth in size of the massive galaxies at z = 0.1 is shown in the top left panel of Fig- over time. ure 3. The stellar mass–size relation at z = 1 is o"set from the local relation by ~ 0.21 dex, With this research we have demonstrated with a slope consistent with the slope seen that wide-!eld, near-infrared adaptive op- for galaxies with same stellar masses in the tics observations, such as those we obtained local Universe. with GeMS/GSAOI, are critical in order to characterize the galaxy population at high The results, obtained here for the !rst time for redshifts. GeMS is limited by the magnitudes galaxies in a cluster environment, are consis- of the natural guide stars (NGS) used to com- tent with previous !ndings for !eld galaxies, pensate for tip-tilt and plate-scale mode vari- indicating that the primary mechanism for ation (currently R < 15.5 magnitude). High- galaxy growth in size since z ~ 1 in clusters is redshift clusters are located in regions where either minor mergers or adiabatic expansion bright stars are absent or have magnitudes due to AGN mass loss winds, or both. If major fainter than the current limit. The new NGS January 2017 | 2016 Year in Review GeminiFocus 5 Figure 3. Stellar mass-size relation for the cluster SPT-CL J0546-5345 compared with other work in the literature.

Top left: Ks-band stellar mass-size relation at z = 1. The relation, defined by our cluster members, has a slope of β = 0.74, consistent with, but offset by, 0.21 dex from the z = 0 relation shown as the dashed line. Both relations trace the underlying stellar population. Top right: stellar mass-size relation for the SPT cluster measured in

GeMS/GSAOI Ks (red filled circles and black solid line), HST ACS F814W (rest-frame system (NGS2) at Gemini South will extend B-band shown as blue down triangles and dot-dashed line), the guide stars accessible to GeMS by 2-2.5 and F606W (rest-frame U-band as magenta magnitudes deeper than the current system. squares and dashed line) bands. Bottom This new capability will allow us to extend left: other z ~ 1 samples from the literature, the observations to massive galaxy clusters measured in various rest-frame wavelengths. beyond redshift z ~ 1 in order to determine Rest-frame B-band measurements are shown the main cause of galaxy growth in size since in blue, and rest-frame V-band in green. cosmic high noon. Bottom right: the effect of resolution on the stellar mass-size relation. Filled red circles and

This work is accepted for publication in solid line depict our GeMS/GSAOI Ks -band Monthly Notices of the Royal Astronomical Soci- imaging (FWHM ~ 110 milliarcseconds). Blue ety and is availabe at this site. down triangles and dot-dashed line show measurements from our imaging smoothed to the resolution of Gemini’s Near-Infrared Camera and Multi-Object Spectrometer (220 Sarah Sweet is a Postdoctoral Research Fellow milliarcseconds); magenta squares and dashed line are from smoothing to the resolution of the at the Australian National University. She can be FourStar infrared camera (510 milliarcseconds) contacted at: [email protected] at the Magellan Baade 6.5-meter telescope Rodrigo Carrasco is an astronomer at Gemini at Las Campañas Observatory in Chile. The South in Chile. He can be reached at: horizontal dotted lines indicate the physical size [email protected] at z = 1, which corresponds to the resolution of each instrument. Fernanda Urrutia is an outreach astronomer at Gemini South. She can be reached at: [email protected]

6 GeminiFocus January 2017 | 2016 Year in Review Andy Skemer October 2016

A Gemini Spectrum of a World Colder than a Night on Maunakea

Gemini North’s unique spectroscopic capabilities at 5 microns combined with queue scheduling delivered challenging deep spectra of a nearby, very cool brown dwarf. The results provide a strong analog of a Jupiter-mass planet and the coolest known compact object outside of our Solar System.

For more than 50 years, scientists have observed our Solar System’s gas giant planets in the infrared. At these wavelengths, it is possible to measure their intrinsic luminosities, chemical abundances, and thermal pro!les. We now live in an age where thousands of planets have been discovered orbiting other stars. For a handful of these worlds, we are beginning to study their individual properties in a way that emulates Solar System studies from 50 years ago.

Figure 1. Left: VLT image of Jupiter at 5 microns Image credit: Leigh Fletcher Right: Gemini spectrum of WISE 0855 at 5 microns (the faint white vertical line).

January 2017 | 2016 Year in Review GeminiFocus 7 its photometry, this implies an ef- fective temperature of ~ 250 K (the coldest known compact object out- side of our Solar System) and a mass

of 3-10 MJupiter. When WISE 0855 was discovered, a #urry of interest in characterizing its atmosphere ensued. Models predict that at 250 K, WISE 0855 should have a spectrum dominated by water va- por, phosphine, and perhaps a sub- tle in#uence from water clouds. But the method typically used to study brown dwarf atmospheres — near- infrared spectroscopy (1-2 microns) — is infeasible on current facilities due to WISE 0855’s intrinsic faintness (J = ~ 25 magnitudes). Counterin- The di$culty of studying exoplanets is that tuitively, the best way to obtain a spectrum Figure 2. they are much fainter than their host stars. of WISE 0855 is with ground-based M-band GNIRS spectrum of Dedicated instruments, such as the Gemini (5 micron) spectroscopy, which, due to the the 250 K brown Planet Imager, can detect the light of warm sky background brightness, is usually far less dwarf, WISE 0855. Jupiter-mass analogs. However, the capabil- sensitive than other wavelengths. As WISE WISE 0855 is our ity does not yet exist to image a planet as 0855 has an M-band magnitude (measured first opportunity to cold as Jupiter around another star. study an extrasolar from WISE) of 13.9, it is easier to detect at planetary-mass An alternative approach is to study free- M-band than J-band. There are currently no object that is nearly #oating planets and brown dwarfs. These space-based 5-micron spectrographs. as cold as our own objects slowly cool as they radiate away the gas giant planets. energy from their gravitational collapse, with Enter Gemini no core fusion to create new energy. Brown The previous faintest spectrum ever taken dwarfs can be found over a much wider tem- from the ground at M-band was a Gemini perature range than exoplanets. And tem- Near-Infrared Spectrograph (GNIRS) spec- perature, rather than mass, dominates the trum of Gliese 570 D which is 1.6 magni- appearances of self-luminous planets and tudes brighter than WISE 0855. Scaling from brown dwarfs. previous observations, a low-resolution, By far the best extrasolar analog to Jupiter low signal-to-noise GNIRS spectrum of WISE is the brown dwarf WISE 0855. Kevin Luh- 0855 was just barely possible in a 14-hour man of Pennsylvannia State University dis- integration (29 hours including overheads). covered this free-#oating object in 2014 But there are always practical considerations while searching Wide-!eld Infrared Survey when working at an instrument’s limits. Explorer (WISE) satellite data for extremely Could we keep an invisible object moving 8 red objects with high proper motions. Us- arcseconds per year in the slit for 29 hours ing the NASA Spitzer Space Telescope, over the course of many nights? Would we Luhman determined that WISE 0855 is just see enough of a trace in two-hours clock time two parsecs from the Sun; together with to be able to co-add from night-to-night? In

8 GeminiFocus January 2017 | 2016 Year in Review the end, we saw a faint trace after our !rst established technique from our friends who Figure 3. two-hour observation block, and two months study Jupiter, we inserted an optically thick Upper Left: Water cloud later, we had a reasonable spectrum (Figures water cloud deep in the photosphere of our models fit better than cloud-free models. 1 and 2). model atmosphere, to see if it would pro- Upper Right: WISE 0855 duce the muting seen in our spectrum. The This observation could not have been done looks strikingly similar cloudy model !t signi!cantly better than the anywhere else. The combination of Gem- to Jupiter from 4.8-5.15 cloud-free …one (Figure 3, upper left). How- microns. Shortward of ini’s low-emissivity silver primary coating, ever, water clouds are notoriously di$cult to 4.8 microns, the spectra queue-mode scheduling (that provided two model. WISE 0855 is just our !rst chance to diverge as Jupiter is hours per night over 14 nights), dry Mau- apply these models to an extrasolar object. dominated by phosphine, nakea weather, and a fantastic observing while WISE 0855 is sta" were all necessary to obtain such a faint dominated by water spectrum. Before our Gemini observation, Measuring Up vapor. there had never been an M-band spectrum Lower Left: Our WISE By far the closest analog to WISE 0855 is Ju- of a brown dwarf or extrasolar planet colder 0855 spectrum is piter, which has a temperature of ~130 K. sensitive to a Jupiter than 700 K. We compared our WISE 0855 spectrum to abundance of phosphine, As theoretical work suggested, WISE 0855 one of Jupiter’s and noticed striking similari- but none is seen. should have a spectrum dominated by wa- ties from 4.8-5.15 microns (Figure 3, upper Lower Right: Our ter vapor. When we !t the Wise 0855 data right), wherewhere water vapor absorption WISE 0855 spectrum is marginally sensitive to to our initial cloud-free model, all of the features dominate both objects. Shortward deuterated methane, but wiggles in the spectrum were indeed the of 4.8 microns, the spectra diverge. Jupiter the feature is blended result of water vapor but their signature shows phosphine absorption, while WISE with water vapor appeared more muted. Borrowing a well- 0855 does not (Figure 3, lower left). features that are not well understood.

January 2017 | 2016 Year in Review GeminiFocus 9 Phosphine has long been held as evidence of Gemini was designed to do thermal infra- turbulent mixing in Jupiter’s atmosphere. In red spectroscopy, and Maunakea is the best chemical equilibrium, phosphine is convert- site on Earth to do it. From the telescope, to ed to phosphorus trioxide at temperatures the weather, to the instrument and observ- less than ~1,000 K. In Jupiter, hot phosphine- ers, a lot had to work right to complete this rich gas from the interior is mixed into the observation. It’s a testament to Gemini that photosphere at a faster rate than the phos- when WISE 0855 was discovered, GNIRS was phine is destroyed. WISE 0855 does not show ready and able to obtain a spectrum for our the same mixing behavior, despite the fact team’s work. that it is warmer than Jupiter and should not have to mix phosphine as far. This result will be studied in more detail in a future paper. Andy Skemer is an Assistant Professor at the Uni- versity of California Santa Cruz. He can be con- tacted at: [email protected] Future Explorations

WISE 0855 will be an early target of the James Webb Space Telescope (JWST). But surprises in its spectrum suggest that we need to continue iterating our theoretical understanding of cold brown dwarfs and exoplanets before JWST launches (Figure 3, lower right). This Is Gemini done with WISE 0855? Hopefully not; having solved many of the technical problems that make faint ther- mal-infrared spectroscopy so di$cult, we have been allocated time to pursue its 3.8- 4.1 micron spectrum. At these wavelengths, we expect to see the in#uence of methane chemistry instead of water chemistry, and we will re!ne estimates of WISE 0855’s lumi- nosity, which directly impacts its tempera- ture and mass.

We also are continuing to study the coldest brown dwarfs at M-band. Previous observa- tions only went down to 700 K. There’s a big jump from 700 K to 250 K, which we expect contains the formation of water clouds. With !ve more brown dwarfs spanning the 250- 700 K gap, we hope to study the depths of water absorption lines, which models pre- dict will increase with decreasing tempera- ture until water clouds start to mute them, and/or remove a signi!cant fraction of the available water vapor.

10 GeminiFocus January 2017 | 2016 Year in Review Brian Nord and Elizabeth Buckley-Geer July 2016

A Case of Warped Space: Confirming Strong Gravitational Lenses Found in the Dark Energy Survey

Spectroscopic observations with the Gemini Multi-Object Spectrograph at Gemini South provide precise redshifts that con!rm strong gravitational lensing systems discovered in early Dark Energy Survey (DES) data. These con!rmations are the !rst at galaxy- and galaxy-cluster scales in the multi-year e$ort of lens follow-up enabled by a Large and Long program.

Massive astronomical objects su$ciently warp space-time to change the path of light on its way from distant galaxies to an observer. Consequently, strong gravitational lensing systems are revealed to us by the distorted images of these galaxies.

Most of the strong lensing systems discovered during the last decade were found by search- ing through existing data or through new observational campaigns. These investigations across many wavebands — from the optical to the millimeter — have resulted in ~ 1,000 candidates or con!rmed lensing systems of varying masses, with distorted galaxy images in arcs of varying sizes around them.

The Dark Energy Survey (DES; @TheDESurvey) — an ongoing international, collaborative e"ort to produce the largest and deepest contiguous map of the southern sky to date in optical wavelengths — has the potential to add to the roster twice as many strong lenses in the optical as have ever been discovered across all wavelengths.

January 2017 | 2016 Year in Review GeminiFocus 11 Finding and con!rming candidates are the ous solutions, which describe the di"erent !rst steps in measuring cosmic structure and paths light can take from a single source, as dark energy with strong lenses. The results well as the amount of magni!cation in the will help us to understand why the Universe lensed image. A single source galaxy can ap- is accelerating and not being slowed by the pear highly magni!ed and have multiple im- mass it contains. ages — both telltale signatures of a strong lensing system. When Space Gets Warped One maxim of Einstein’s Theory of General What Can Strong Lenses Tell Us Relativity is that space-time — the concept about the Universe? that space and time are one — tells energy With strong gravitational lensing we can ex- how to move, and energy tells space-time amine in detail galaxies normally too faint how to curve. Gravitational lensing dem- to observe. The observations also provide onstrates both of these concepts: the path an avenue for studying galaxy evolution at of light traveling from a distant object (like epochs earlier in the Universe than would a galaxy) is de#ected by a depression in the be available otherwise. The total lensing fabric of space-time caused by a massive mass and its spatial distribution dictate the object nearer to us. The more massive this morphologies of lensed images. By measur- intervening lensing object, the larger the ing the amount and type of distortion of the crater, and the more distorted the observed source image, we can learn more about the image of the distant source galaxy. mass distribution (including that due to dark Gravitational lenses act like terrestrial lenses matter) in the lensing galaxies or clusters. made of plastic or glass, bending light in Moreover, particular con!gurations of lens- ways we can model well with geometric op- es can help constrain dark energy models. tics; the equations have multiple simultane- In systems with two or more source galaxies Figure 1. Color images of six strong lenses confirmed with Gemini South spectroscopic follow-up: a) DES J0221-0646, b) DES J0250-0008, c) DES J0329-2820, d) DES J0330-5228, e) DES J0446-5126, f) DES J2336-5352. Each of these systems is a galaxy group or richer cluster, but just one or a few galaxies near the center of the cluster cause most of the lensing. (All figures reproduced from Nord et al., 2016.)

12 GeminiFocus January 2017 | 2016 Year in Review along the line of sight behind the lens (e.g., Searching through this area of sky is the SDSS J0946+1006, which shows multiple !rst challenge in !nding lenses. A team of concentric rings) the relationship between ~ 20 DES scientists visually scanned the SV the distances and the lens mass contains sky area, looking primarily for morphologi- information about the dark energy densi- cal features — multiple images, arcs, and ty. However, these are rare: only 10 are ex- full (Einstein) rings. We !rst performed a pected in the entire DES footprint (Gavazzi non-targeted search of the entire SV area, et al., 2008). Also, time-delay measurements without focusing on any particular !elds of variable-luminosity objects, like lensed or objects. We then undertook a targeted quasars, can allow for measurements of the search in the !elds of galaxy clusters in the Hubble constant (Refsdal et al., 1964). DES footprint. The redMaPPer cluster-!nder (Ryko" et al., 2014) provided optically se- We see a variety of morphologies in the lected clusters. Overlapping !elds of South !rst galaxy- and galaxy-cluster-scale lenses Pole Telescope (SPT) data provided clusters discovered in early DES data sets, shown in selected with the Sunyaev-Zel’dovich e"ect Figure 1; the lensed sources range in red- (Bleem et al., 2015). shift, 0.80 < z < 3.2. The STRong-lensing In- sights into Dark Energy Survey (STRIDES; The resulting list of candidates was then re- Treu et al., 2015) program aims to discover !ned by a group of three expert scanners, and follow up new time-delay lenses in DES who reduced the total number of highly data. Under these auspices, we have also ranked candidates to 53. discovered and con!rmed two lensed qua- We also predicted the number of lenses we sars at z ~ 1.6 and ~ 2.4 (Agnello et al., 2015). could !nd in DES by comparing our list to Although these discoveries were made us- a di"erent sample of highly ranked candi- ing Magellan/Baade, our Gemini Large and dates/con!rmed lenses found in the Cana- Long program is providing the capability for da-France-Hawai‘i Telescope Legacy Survey future con!rmations. (CFHTLS) Strong Lensing Legacy Survey (S2LS; More et al., 2012) — including source Detective Work galaxies that survived a cut on the DES mag- nitude limit (24.5 magnitude in g-band). DES is a deep-sky survey that covers 5,000 There may be over 2,000 similar lenses in the square degrees (sq. deg.) of the southern full DES area, and about 100 in the SV region. Galactic Cap in !ve optical !lter bands (g, r, While we accounted for the relative sky ar- i, z, and Y). The main instrument for DES is eas and depths of the two surveys, we had the Dark Energy Camera (DECam), a wide- no mechanism to a$rm the e$ciency of hu- !eld (3 sq. deg.) camera mounted on the man visual inspection. Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory in the Chilean Andes (Flaugher et al., 2015). The survey has Con!rming Lenses with !nished three out of the planned !ve years. Spectroscopic Follow-up The Science Veri!cation (SV) season took place after commissioning in late 2012 be- The next puzzle piece we needed was con!r- fore the o$cial science survey began. The SV mation that a source galaxy lies beyond the data cover 250 sq. deg. (< 5% of the full area) putative lensing galaxy. This requires a su$- and provide the imaging data for this work. ciently precise spectroscopic measurement of the source galaxy’s redshift. Photometric

January 2017 | 2016 Year in Review GeminiFocus 13 redshifts provide a measure of distance, but scope (with an overlap of one system). We they are relatively imprecise and much less con!rmed six strong lensing candidates with reliable for the more remote galaxies likely Gemini South, rejected two, and the status to be lensed. of 13 remain inconclusive. For the rejected systems, we found that the putative source To measure redshifts, we look for speci!c galaxies were actually foreground galaxies. features, like emission or absorption lines, in The inconclusive systems may have spec- the spectra of source galaxies: the higher the tral features at higher wavelengths, which redshift, the further these features shift from would require the use of other instruments their rest wavelength. We use the R150 grat- or telescopes. ing in conjunction with the GG455 !lter to obtain spectra with a wavelength coverage Let’s look in detail at some of the con!rmed of 4500-10000 angstroms (Å). For the sourc- systems. Figure 2 shows spectra of the source es that we expect to be late-type emission galaxy images A1 and A2, along with images line galaxies, this would allow us, in many of the lensing system DES J0221- 0646. Tak- cases, to detect [OII]3727 to z ~ 1.7, H-beta ing into account the absence of other spec- to z ~ 1.0, and Lyman-alpha in the range 2.7 tral features, we assign the features at 4535 Å < z < 7.2. We use the B600 grating to obtain to be Lyman-alpha, which gives a redshift of spectral coverage of 3250-6250 Å, which ~ 2.752, placing it behind the redshift 0.672 would allow us to detect sources with z > 2.0 lensing galaxy. that emit Lyman-alpha. The middle color image of Figure 2 shows We acquired spectroscopic data for 21 of an Einstein radius estimated by manually !t- the 53 systems: 17 were observed at Gem- ting a circle that passes through the spectro- ini South (taken through the Gemini Large scopically con!rmed source images, where and Long program), and !ve were observed the center is chosen to be the arcs’ center of with the Inamori Magellan Areal Camera and curvature. With these radii, we estimated the Spectrograph at the Magellan/Baade tele- mass enclosed within that circle. This system, Figure 2. DES J0221- 0646. The spectra for source images A1 and A2 are shown on the left. The gray-scale DES g-band image in the upper right shows where we placed the GMOS slits as needed to optimize flux from the source images. In the color co-add image in the middle right panel, the Einstein radius is marked by a white arc.

14 GeminiFocus January 2017 | 2016 Year in Review Figure 3. DES J0446-5126. The spectra for source images B1 and B2 are shown on the left. The spectrum for A is not shown, but has an emission line consistent with an interpretation as a foreground object.

like the others from this con!rmed sample, We are currently reducing spectroscopic are challenging to model in detail for a pre- data from the 2nd season of Gemini Large cise mass measurement: while there are and Long program observations on GMOS multiple images of the lensed galaxy, they South. We are also developing and exploit- both occur on one side of the lensing gal- ing automated lens-!nding methods, such axy. We would need well-resolved counter- as ring-!nders, arc-!nders, and machine- images for a more precise measurement. The learning algorithms. With these tools we will limited resolution of DES images obscures continue to search for the lenses that can some lensing features, especially for systems reveal the most about dark energy and the with smaller (< 3’’) Einstein radii. cosmic expansion rate. Large cosmologi- cal surveys, like DES and the Large Synoptic In Figure 3, we see another con!rmed lensing Survey Telescope (LSST), will have a plethora system, DES J0446-5126. Prominent Lyman- of data on strong lensing systems. Our main alpha emission lines in both arcs B1 and B2 challenges will be not only to obtain com- occur at the same observed wavelength of plete and pure samples of lenses, but also to 5117 Å, originating in a single source at red- !nd those precious few systems that enable shift 3.2. The object labeled A also has emis- dark energy science. sion lines (not shown), which we interpret as [OII]3727 and [OIII]5007: this must then be a foreground object at redshift 0.17. Brian Nord is a cosmologist and postdoctoral researcher at Fermi National Accelerator Labo- A Warped Future ratory in Batavia, Illinois. He can be reached at The spectroscopic observations taken [email protected] or on Twitter @briandnord. through the Gemini Large and Long pro- Elizabeth Buckley-Geer is a scientist at Fermi gram made it possible to con!rm six new National Accelerator Laboratory. She can be gravitational lensing systems in DES data. reached at [email protected].

January 2017 | 2016 Year in Review GeminiFocus 15 April 2016 Jennifer Andrews Dusting the Universe Figure 1. GMOS-S g’, r’, and i’ color composite image of SN 2011ja from April with Supernovae 2012 (day 112). In the original image, the supernova looks red Long-term observations made with the Gemini Multi-Object due to a combination Spectrograph at Gemini South, combined with Spitzer space of bright hydrogen (Hα) emission, strong telescope data, reveal how core collapse supernovae can make extinction around the an important, yet largely unrecognized, contribution to the object, and new dust formation. overall dust budget of the Universe.

Stars more than eight times the mass of our Sun end their lives in fantastic explosions we call core collapse supernovae (CCSNe). Most common are Type II-Plateau (Type II-P) events, which show broad hydrogen emission lines in their spec- tra along with a near constant plateau of optical luminosity throughout the !rst ~100 days.

It has long been known that heavy elements and dust grains can be formed in the leftover material ejected in a CCSN ex- plosion. However, only recently have we recognized the im- portance of this contribution to the overall dust budget in the Universe.

Generally we thought that asymptotic giant branch stars were the main contributors of dust in galaxies; these low- to intermediate-mass stars form dust grains in their stellar winds over millennia and deposit them into the interstellar medium (ISM). But this does not explain how high-redshift galaxies (z > 6) can have more dust than their young ages should allow. Thus we began to revisit the role that CCSNe play in dust pro- duction, especially their ability to quickly return gas and dust to the ISM.

16 GeminiFocus January 2017 | 2016 Year in Review Extending the Search The Evolution of SN 2011ja with GMOS Using the new B600 grating and 0.75 arcsec- Over the past decade, our team has been us- ond slit, we obtained GMOS-South medium- ing ground- and space-based optical and IR resolution spectra of SN 2011ja — 84, 112, imaging and spectroscopy to look for signa- 159, 450, and 807 days after explosion (Fig- Figure 2. tures of dust formation in young CCSNe. In ure 2). We also obtained g’, r’, and i’ imaging (Top): Hα evolution particular the size and sensitivity of GMOS at the same time (Figure 1). Both datasets of SN 2011ja during the first 8 months. The has allowed us to follow a collection of ob- are supplemented by European Southern degredation of the red Observatory optical and NIR photometry jects for years after explosion in a search for peak at ~2,500 km/s is a the three telltale signs of grain condensation. (Figure 3), as well as optical spectra. sign of dust formation. (Bottom): Full First, as dust forms, the optical luminosity We immediately noticed the strange multi- spectroscopic evolution peaked shape of the hydrogen lines (Figure 2, will decrease while almost simultaneously of SN 2011ja over the the near-infrared (NIR) will increase, as the top) that appeared as the SN was transition- first two years. dust grains absorb the shorter wavelength light and re-emit it in the IR. Grain formation will also alter the optical spectrum, creating asymmetric and blue-shifted lines as the dust grains attenuate the red (receding) side of the ejecta preferentially. And while we initially believed that the dust grains could only condense 300-600 days af- ter explosion (when the ejecta had expand- ed and cooled) there have been more and more con!rmed cases of dust forming much earlier, within 100 days of explosion. An early onset of dust formation can oc- cur when shocks interact with nearby cir- cumstellar material (CSM), creating an area known as the cool dense shell (CDS) with temperatures and densities appropriate for grain growth. This not only allows a separate channel for dust formation in CCSNe, but can also reveal important properties of SN evolution and progenitor mass loss. In February 2012, we also began using GMOS in an extensive observing campaign on SN 2011ja in NGC 4945 (Figure 1). This “normal” Type II-P SN, located ~ 11 million light years away, has an absolute I-band magnitude of ~ -18.3. Our goal was to follow SN 2011ja from near peak to well past 600 days. This allowed us to look for both chan- nels of dust formation, and to quantify the mass and composition of any forming dust.

January 2017 | 2016 Year in Review GeminiFocus 17 ing out of the plateau phase. Most interest- All observational signs pointed to dust for- ingly, the strength of the blue peak of Hα in- mation occurring sometime around day 100. creases relative to the red, and the line peaks Together with the spectral signatures of CSM themselves begin to #atten over time. interaction, this would seem to indicate that the dust is in the CDS, formed between the Multipeaked emission lines are mostly at- forward and reverse shocks created as the tributed to a toroidal or disk geometry of ejecta plows into the pre-exisitng gas and surrounding CSM material, while the #atten- dust lost by the progenitor before the end ing is caused by the ejecta interacting with of its life. the CSM. From the optical spectra alone, we can therefore infer that the SN is running into asymmetric mass-loss from the SN pro- Modeling the Dust genitor. Chandra X-ray observations provide Now that we had observational evidence of further support as the SN’s early X-ray emis- dust grains forming in SN 2011ja, we could sion only increased over the !rst 100 days. turn our attention to modeling the dust: how The degrading of the red peak with time much, what kind, and where was it located. was our !rst clue that dust was forming early Using our 3D Monte Carlo radiative trans- on, as the grains were obscuring the reced- fer code MOCASSIN and our optical and IR ing side of the ejecta more than the ap- observations, we modeled various geom- proaching side. While this in itself may have etries and compositions of dust, including a been enough to determine dust was form- spherical shell of smooth and clumped dust, Figure 3. ing within a few months of explosion in SN as well as a smooth distribution of dust in a Optical and NIR light 2011ja, the IR and optical light curves also torus of increasing inclinations around the curves of SN 2011ja. added credence: there is a 0.4 magnitude The NIR curves have system. We limited our dust composition to brightening in the K-band between day 121 been shifted down a carbon grains only, since 10.8 micron Very and 243, and a simultaneous drop of ~ 0.5 magnitude for clarity, Large Telescope observations did not detect magnitude in the optical brightness as can and the dashed line strong silicon emission. indicates 56Co decay. be seen in Figure 3. The modeling of four GMOS and Spitzer Infrared Array Camera epochs revealed about 1 x 10-5 solar masses of pre-existing dust located about 3,500 AU away from the center of the SN, and up to 6 x 10-4 solar masses of newly formed dust in a torus inclined roughly 45º from edge on and closely surrounding the SN.

This dust mass is still much less than that observed from SN 1987A and other SN remnants. By continuing to follow SN 2011ja as it expands and cools, we will likely see more and more dust being formed, albeit at a much lower temperature.

18 GeminiFocus January 2017 | 2016 Year in Review Signs of a Massive Progenitor The Future While we had found evidence for early dust Our group is continuing to study CCSNe at formation within the !rst 100 days, we need- late times to look for increased dust forma- Figure 4. ed to continue observing the object as long tion. Speci!cally we are monitoring the dust Day 807 spectrum as possible to search for additional grain for- as the ejecta cools and expands, to deter- (purple) of SN 2011ja mation in the ejecta. After 400 days or so, we mine how the progenitor mass of the SN showing enhanced noticed little change in its optical luminosity correlates with dust mass. We currently have blue emission. (Figure 3). Normally we would expect to see a a project underway using GMOS to look at Comparison with the fading of about 1 magnitude every 100 days SNe with ages between 4-60 years in order light echo spectrum due to the radioactive decay of 56Co which to model their Hα emission. created from an integrated fluency powers the late-time lightcurves of SNe. Tests done on SN 1987A have shown that of the first 84 days Light echoes scattering o" dust clouds be- the shape and strength of the broad Hα line (red) indicates that tween us and the SN, or radiative shocks can be correlated to dust mass. This will be a light echo cannot be responsible for plowing into nearby CSM, may have caused amazingly useful, especially in the era before the flux bluewards of this late-time brightness. But most likely in James Webb Space Telescope, since data 6,000 Å. The orange this case the SN continuum had faded be- suggest the peak dust production may occur and yellow spectra low the brightness of the parent star cluster in the cooler dust regimes only accessible by are synthesized stellar from which the massive progenitor star was long-wavelength instruments. populations created born. This scenario would allow both the with Starburst99 for 3 and 6 Myr. It is possible strong broad Hα emission line, and a bright that the late-time Jennifer Andrews is a postdoctoral researcher at blue continuum. luminosity has a large the University of Arizona. She can be reached at: Comparing the day 807 spectra with Star- component of the [email protected] parental stellar cluster. burst99 stellar synthesis models of young massive star clusters (Figure 4) indicates that the late-time luminosity most likely has a large component of the parental stellar clus- ter, which is between 3-6 million years (Myr) young, corresponding to a SN progenitor mass of 20-30 Suns.

The absolute magnitude at maximum (I = ~ -18.3) in tandem with the short plateau duration and the steep drop into the radio- active decay phase of the optical light curve, all point to a CCSN with a small hydrogen envelope.

Combined with the estimated age of the parent cluster, this would suggest SN 2011ja likely went through a strong mass-loss phase not long before eruption.

January 2017 | 2016 Year in Review GeminiFocus 19 Gemini sta! contributions Figure 1. The top panel shows the spectrum of KH 15D during its “bright” phase, when the amount of direct starlight was greatest. Science Highlights The middle spectrum (“intermediate” phase) was taken when star B was just below the edge This 2016 Year-in-Review highlights the innovative science being of the ring. Both spectra done by the Gemini user community. in the bottom panel were obtained during “faint” phases from two different cycles, when both stars were near periastron and January 2017 the contribution from starlight was minimized. Unscrambling a Complex Young Stellar System The spectrum from November has been offset Nicole Arulanantham of Wesleyan University (Middletown, Connecticut) and colleagues used by 1.5x10-15 W m-2 μm-1 for the Gemini Near-InfraRed Spectrograph (GNIRS) on the Gemini North telescope to target the comparison to the data binary T Tauri system V582 Mon (KH 15D) — two K-type stars in a circumbinary ring that is in- from December. clined to the binary’s orbit.

The team obtained data at three di"erent orientations of the system’s two young stars (Figure 1), allowing them to study several key aspects of this complicated system — including characterizing the photosphere and magnetosphere of the companion star (B), exploring a jet of material associated with a bipolar out#ow, and probing the scattering properties of its circumbinary ring. The research uncovered an excess of near- infrared radiation that is possibly the signature of a self-lu- minous 10-Jupiter-mass planet. While this unresolved planet displays the expected excess in infrared radiation, as well as a 2-micron spectral feature that may be due to methane or am- monia, other anticipated signs of these two compounds went undetected in the observations. The team’s spectroscopic ob- servations also indicate that a mixture of water and methane ice grains lie within the circumbinary ring — close enough to the primary stars that the frozen methane must be shielded by dust from direct radiation.

Finally, in addition to determining that star B is an early K-type subgiant, the research revealed variable helium I emission in star B’s magnetosphere due to ongoing mass accretion. The

20 GeminiFocus January 2017 | 2016 Year in Review team’s paper is accepted for publication in The Astrophysical Journal (view here).

High-mass Young Stellar Objects: Are all Stars Created Equal? A team of astronomers using the Gemini Near-infrared Integral Field Spectrograph (NIFS) on Gemini North have found the strongest evidence yet that massive stars form in much the same way as do their lower-mass brethren.

In addition to the Gemini observations, the work includes data from NASA’s SO- FIA airborne observatory, Calar Alto Ob- servatory, and the European Southern Observatory. The results show that when massive stars form, they consume chunks of personic speeds and ingested by the forming Figure 2. their surrounding accretion disks, leading to star. The team estimates that the outburst be- Gemini post outburst episodic explosive outbursts — much like gan about 16 months ago and appears to still K-band NIFS spectrum (black at top) of the red- those known to occur during the formation be active, albeit much weaker. shifted outflow cavity of average mass stars like our Sun (only more of S255IR NIRS 3. The intense). This !nding may have a profound pre-outburst spectrum impact on the way some astronomers believe Cluster’s Advanced Age is in obtained with SINFONI/ massive stars grow, namely by the fusion of Razor-sharp Focus VLT is shown in red at less massive stars. Researchers using the Gemini Multi-conju- bottom. The Gemini spectrum in the outburst gate adaptive optics System (GeMS), com- The international team of astronomers, led phase shows a large by Alessio Caratti o Garatti of the Dublin In- bined with the Gemini South Adaptive Optics number of emission lines stitute for Advanced Studies in Ireland, pub- Imager (GSAOI), probed the depths of the typical of disk-mediated lished its work in the November 14th issue of highly compact globular cluster 6624 (Fig- accretion outbursts. the journal Nature Physics (available here). It ure 3). These data reveal pinpoint star images was thought that an accretion disk could not with a uniformity across the crowded !eld, al- survive around a higher mass star due to the lowing the team to perform precise photom- star’s strong radiation pressure, and thus it etry deep into the cluster’s crowded core. would not be a viable mechanism for produc- The team also detected a clear “main-se- ing the most massive stars, some of which can quence knee” (Figure 3, inset); this distinctive exceed 50-100 solar masses. bend in the evolutionary track of low mass The developing star observed in this study, main-sequence stars is extremely di$cult to S255IR NIRS 3 (Figure 2), lies some 6,000 detect without ultra-precise photometry. In- light years distant and has a mass estimated deed, this is the !rst time the feature has been at about 20 solar masses. The Gemini obser- identi!ed in this globular cluster, and it al- vations reveal that the explosive outburst’s lowed the team to determine the cluster’s age source is a huge clump of gas, probably about with extremely high precision: about 11.5- twice the mass of Jupiter, accelerated to su- 12.5 billion years. January 2017 | 2016 Year in Review GeminiFocus 21 The observations spanned a period of 29 months and revealed patterns in the vol- canic activity over time and location on the satellite (Figure 4), but also resulted in new questions.

According to University of California Berke- ley (UCB) Graduate Student Katherine de Kleer, some of the eruptions appeared to progress across the surface over time, as

Figure 3. According to !rst author Sara Saracino of Gemini Observatory the University of Bologna, this is the most GeMS image of globular accurate, and deepest, near-infrared col- cluster NGC 6624 or-magnitude diagram ever produced of NGC if one eruption somehow triggered another revealing individual 6624 and perhaps the best ever made for any stars clear to its core. 500 kilometers away. “While it stretches the The inset shows the bulge cluster. The results of this research are imagination to devise a mechanism that color-magnitude accepted for publication in The Astrophysical could operate over distances of 500 kilome- diagram with the main- Journal, and a preprint can be found here. ters, Io’s volcanism is far more extreme than sequence knee visible. anything we have on Earth and continues to The extreme sharpness amaze and ba&e us.” De Kleer led the analysis of this adaptive Monitoring Io’s Volcanoes with of the data for this study with her advisor at optics image allows Adaptive Optics researchers to perform UCB, Imke de Pater. The longest frequent, high-resolution imag- very precise photometry The results were presented at the American on individual stars — a ing of Io’s thermal emission is providing in- Astronomical Society’s Division of Planetary task requiring exquisite sights on the Jovian moon’s volcanoes, thanks Sciences and the European Planetary Sciences imaging across the to a joint program between the Gemini North entire field, which would Congress in Pasadena, California, in October. telescope (with the Near InfraRed Imager and be a challenge for De Kleer and de Pater presented the results spectrometer [+Altair adaptive optics instru- most adaptive optics jointly based on a pair of papers in the journal ment pairing) and the W.M. Keck Observa- systems. Composite color Icarus, which are available here and here. image by Travis Rector, tory. Gemini’s queue scheduling provided University of Alaska the additional #exibility necessary to assure Anchorage. adequate coverage in the time domain. Image credit: Gemini Observatory/AURA

22 GeminiFocus January 2017 | 2016 Year in Review Figure 4. A sample of Io images obtained from the Gemini North telescope using NIRI with the Altair adaptive optics system for tracking volcanic activity over a 29 month period. Image credit: Katherine de Kleer and Imke de Pater, UC Berkeley/ Gemini Observatory/ AURA/W.M. Keck Observatory

Figure 5. The dark galaxy Dragonfly 44, observed using GMOS- North, in wide-field (left) and close-up (right). Dragonfly 44 is October 2016 very faint for its mass, and consists almost half-light radius), and the Gemini imaging A Dark Matter Milky Way entirely of dark matter. shows the large population of globular clus- Astronomers have discovered a massive gal- Image credit: P. van ters in the halo. Considering theoretical mod- axy that is almost entirely dark matter. The gal- Dokkum et al., Gemini els that include the halo, the researchers con- Observatory/AURA axy, called Dragon#y 44, has very low surface brightness and was discovered only in 2014. New Fast Turnaround program observations using the Gemini Multi-Object Spectrograph (GMOS) on Gemini North, as well as spectros- copy from the Keck II telescope also on Mau- nakea, reveal the galaxy’s physical properties. They show that it is like a “failed” Milky Way, in having similar total mass, size, and population of globular clusters, lacking only stars.

The Keck spectroscopy enabled Pieter van Dokkum (Yale University) and collaborators to measure the mass of Dragon#y 44. The deep images from Gemini (Figure 5) then yielded the galaxy’s mass-to-light ratio (48 within the

January 2017 | 2016 Year in Review GeminiFocus 23 Figure 6. clude that the galaxy’s mass is approximately provides some more information and links to Artist’s concept of 12 10 MSun, and that the total galaxy is 99.99% high-resolution images; full results are pub- what the view might dark matter. One speci!c problem this ex- lished in The Astrophysical Journal Letters. be like from inside ample presents is that the formation of stars the TRAPPIST-1 is predicted to have maximum e$ciency at exoplanetary system, Con!rming Nearby Exo-Earths showing three Earth- this mass regime. Dragon#y 44, a con!rmed sized planets in orbit member of the Coma cluster exhibiting a reg- The Di"erential Speckle Survey Instrument around the low- ular morphology, has formed 100 times fewer (DSSI) visited Gemini South for the !rst time mass star. This alien stars than expected. A Gemini press release in June 2016 and is already delivering excit- planetary system ing results, including the validation of is located only 12 nearby Earth-like exoplanets. Previous parsecs away. Gemini observations using the TRAnsiting Plan- South telescope imaging, the highest ets and PlanetesImals Small Telescope resolution images (TRAPPIST) had shown variations in the ever taken of the star, light curve of the star TRAPPIST-1, imply- revealed no additional ing the presence of several Earth-sized stellar companions, planets (Figures 6 and 7). Steve Howell providing strong (NASA Ames Research Center) and col- evidence that three leagues used high-resolution images small (probably rocky) planets orbit this star. from Gemini to con!rm the small size Image credit: Robert and mass of these suggested Hurt/JPL/Caltech planets by ruling out the pres- ence of a very nearby compan- Figure 7. ion. DSSI on Gemini provides Detection limit the highest resolution images analysis for the June available to astronomers any- 22, 2016, Gemini- where and here achieved a res- South observation of TRAPPIST-1. Detection olution of 27 milliarcseconds, limits observed at 692 or 0.32 astronomical units at nm (top) and at 883 nm the 12-parsec distance of TRAP- (bottom). The red line PIST-1. represents the relative 5σ limiting magnitude The host star, TRAPPIST-1, is a as a function of late M dwarf. Such cool stars are separation from 0.027 interesting targets because any to 1.2 arcseconds. At the terrestrial planets around them distance of TRAPPIST-1, would have short periods (of these limits correspond days) and be detectable with to 0.32–14.5 AU. The two listed limiting current technology. At least two magnitudes given of the three known planets in for reference are for this case are very close to the angular separations of star, so too hot even to be in the 0.1 and 0.2 arcsecond. habitable zone. The orbit of the third planet is somewhat uncer- tain now. See the Gemini press release and The Astrophysical Journal Letters for full results.

24 GeminiFocus January 2017 | 2016 Year in Review Powerful Ionizing Sources in the Nearby Universe An international team of astronomers using GMOS on each of the Gemini tele- scopes has obtained the !rst ever close- up images of Lyman-alpha blobs (LABs) at low redshifts of z = 0.3 (Figure 8). LABs may extend up to 100 kiloparsecs, and emit co- pious amounts of Lyman-alpha radiation. They are landmarks of massive galaxy for- mation and have, so far, only been found at high redshifts of about 1.5 or higher. Gemini astronomer Mischa Schirmer and collaborators have shown that LABs may still exist in the low redshift Universe, 4 - 7 billion years later than previously known, based on far-ultraviolet measurements with the GALEX satellite.

One of the biggest mysteries of LABs is their ionizing power source. Various mech- anisms have been suggested, such as cold accretion streams, hidden active galactic nuclei (AGN), star bursts, and supernovae; however, many LABs show no ionizing con- July 2016 Figure 8. tinuum source at all. The researchers found Gemini/GMOS images weak AGN at the cores of the discovered low- A 17-Billion-Solar-Mass Black of four of the new low- redshift LABs. Their low redshifts allowed the redshift Lyman-alpha Hole Surprise blobs, using g, r, and i astronomers to study these objects in much Astronomers using the Gemini Multi-Object filters. From upper left to more detail than their high-redshift cousins. Spectrograph (GMOS) integral !eld unit on lower right: J1505+1944, J1455+0446, J1155–0147 The very luminous and extended nebulae ob- the Gemini North telescope have measured a and J0113+0106. These served require that the AGN must have been 17-billion-solar-mass black hole dominating objects are among the in a very powerful state until a few 1,000- the core of NGC 1600, a large galaxy in the most powerful [OIII]5007 10,000 years ago. Such episodic duty cycles low-density environment of a galaxy group. emitters known in the are typical for AGN, but are di$cult to recog- This is a surprise, given that we expect to !nd Universe, causing the nize otherwise because they last much lon- monster black holes in very massive galaxies green color in these ger than a human lifetime. One of the team’s at the centers of large galaxy clusters. Astron- optical images. Note that the far-UV Lyman-alpha main results is that even a short burst of high omers have also observed luminous quasars radiation is not visible in AGN activity is su$cient to power the LAB’s hosting very massive black holes in the dis- these optical images. Lyman-alpha emission for a very long time. tant Universe, and this result sheds light on large black holes in the more local Universe, This work is featured on the Gemini website suggesting they are likely relics, the descen- and is published in Monthly Notices of the dants of luminous quasars at higher redshift. Royal Astronomical Society. In the high-mass regime, Jens Thomas (Max Planck Institute for Extraterrestrial Physics,

January 2017 | 2016 Year in Review GeminiFocus 25 Figure 9. vide more quantitative information about The relationship the con!rmed exoplanet that the star HD between core radius 95086 hosts and suggest the presence of

(rb) and the black hole multiple planets. Julien Rameau (Université sphere of influence de Montréal, Canada) and colleagues directly (r ) is tighter than SOI observed the planet, called HD 95086 b, and other relationships with the black hole mass, determined its orbital parameters. They !nd such as stellar velocity the orbital semimajor axis around 62 astro- dispersion. nomical units and low eccentricity (ε < 0.21). (Figures 10-11).

The star’s debris disk, where such young planets form, produces additional infrared emission. Considering multiple pieces of evi- dence, the architecture of this system — in- Germany) and collaborators !nd that a host cluding the disk, its gaps, and the con!rmed galaxy’s core radius is a robust proxy for the Figure 10 (below left). exoplanet — likely requires another planet or mass of the central supermassive black hole; A deep K1-band image more in addition to HD 95086 b to explain the of HD 95086 from GPI it correlates more tightly than stellar velocity observations. See more about this work at the clearly shows a planet, dispersion, σ. NGC 1600 is, in fact, something Gemini webpage. The work has been pub- located at about the of an outlier on the more common “M-σ” plot. lished in The Astrophysical Journal Letters. 7-o’clock position Figure 9 shows the relationship between this and within 0.5” of the core radius (r ) and the black hole sphere of central star. b in#uence (rSOI). A Gemini press release fea- N159W: Dissecting Triggered tures the work, and complete results are pub- Figure 11 (below right). Star Formation with MCAO This schematic diagram lished in Nature. Massive stars (greater than eight solar mass- shows observed locations es) shape their surroundings by ionizing the of the planet HD 95086 b local interstellar medium to create expand- (black and red points, with Constraining the Architecture ing HII regions, which may compress nearby error bars) and numerical of the HD 95086 Planetary gas and enhance local star formation. Ob- simulations of possible System orbits (blue lines). Gray serving this starbirth in situ presents a chal- shaded regions mark the New observations obtained using the Gem- lenge because dust hides the strong ultra- locations of inner and ini Planet Imager (GPI) on the Gemini South violet and optical emission of the newborn outer dust rings. telescope, combined with earlier data, pro- stars, and all the activity occurs on very small spatial scales. PhD student Anaïs Ber- nard (Laboratoire d’Astrophysique de Marseille, France) and collaborators have used the Gemini Multi-conju- gate adaptive optics System (GeMS) with the Gemini South Adaptive Optics Imager (GSAOI) to overcome these di$culties.

Figure 12 shows the result. The im- age reveals !ne details (on scales of ~ 0.09 arcsecond) in the near-infrared light that penetrates the obscuring

26 GeminiFocus January 2017 | 2016 Year in Review The discovery of a 0.77 MJupiter exoplanet lo- Figure 12. cated within 0.06 astronomical units of V830 Gemini South GeMS/ Tauri — a young (< 2 million years) T-Tauri star GSAOI near-infrared — con!rms both rapid planet formation and image of the N159W field in the Large early migration. Such early forming “hot Jupi- Magellanic Cloud. ters” likely play a key role in shaping planetary The image spans 1.5 systems overall. arcminutes across, resolves stars to about High-resolution spectroscopy over a 0.09 arcsecond, and is 1.5-month campaign revealed the presence a composite of three of the exoplanet in a telltale spectral “wobble,” filters (J, H, and Ks in leading the discovery team to isolate the sig- blue, green, and red, nal of the planet, !nd its orbit, and determine respectively). Integration its mass (Figure 13). Jean-François Donati time for each filter was 25 minutes. Color (Observatoire Midi-Pyrénées, France) led the composite image by dust of N159W, a young star-forming region work, which took advantage of the novel col- located ~ 150,000 light years distant in the Travis Rector, University laboration between the Gemini Observatory of Alaska Anchorage. Large Magellanic Cloud. The 100 young stel- and the Canada-France-Hawai‘i Telescope Figure 13. lar object (YSO) candidates associated with (CFHT) in GRACES (Gemini Remote Access to N159W lie mostly at the border of the ionized Radial velocity (RV) CFHT ESPaDOnS Spectrograph). GRACES uses measurements of V830 (HII) bubble — where cold, neutral material an innovative 270-meter !ber cable to trans- Tauri, after filtering out accumulates in clumps and subclusters — port light from Gemini North’s 8-meter mirror stellar activity, reveal and displays signs of recent active star forma- to the ESPaDOnS Spectrograph at CFHT. For the presence of a “hot tion. In contrast, the estimated age of the two this work, the researchers also used ESPa- Jupiter.” Data from ESPaDOnS/Gemini, (blue) massive stars and the associated clus- DOnS on CFHT and the spectropolarimeter ter at the bubble’s center is about two million ESPaDOnS/CFHT, and NARVAL on the 2-meter Telescope Bernard NARVAL/TBL are plotted years. Thus, the authors suggest that the !rst Lyot. Full results appear in Nature and are fea- as triangles, circles, and generation of massive stars at the bubble’s tured on the Gemini web page. squares, respectively, with core triggered the recent birth of the YSOs colors that code rotation around the periphery. A Gemini image re- cycles. Lines show fits lease features this work, and full results will to circular (solid) and be published in Astronomy and Astrophysics. eccentric (dashed) orbits. A preprint is now available.

Innovative Gemini/CFHT Partnership Explores a “Hot Jupiter” The exploration of other worlds has shown that gas-giant planets lie very close to their host stars. As they could not have formed in their present locations (radiation would have dissolved them) questions remain: do these giants move close-in when the sys- tem is young, after interacting with the pro- toplanetary disk, or do they only move later, following interaction with multiple planets?

January 2017 | 2016 Year in Review GeminiFocus 27 April 2016 Traces of Planet Formation in a The authors acknowledge other processes Stellar Disk that can create gaps and rings, such as grain fragmentation and ice condensation fronts. Planets form in the disks around young A de!nitive test would be to observe the stars, and the relatively nearby TW Hydrae is planet directly. It would need to be actively an excellent candidate in which to observe accreting material to be bright enough to this process. In polarimetric observations detect easily in future GPI observations. The with the Gemini Planet Imager (GPI) on the Gemini website has some more information, Gemini South telescope, Valerie Rapson and complete results are published in The (Rochester Institute of Technology, New Astrophysical Journal Letters. York) and collaborators probe the disk of TW Hya — from about 80 astronomical units (AU) to within 10 AU of the central star — Seeking Companions of the Figure 14. Coolest Brown Dwarfs Radially scaled Examples of the coolest and least massive polarized intensity brown dwarfs, Y dwarfs, were !rst identi!ed in the J-band shows in 2011. Having temperatures just above the variation of dust density distribution in those of the gas giant planets (around 250 the disk of TW Hydrae. K), they help bridge the gap from stellar The coronagraph blocks objects to planets. The binary nature of any light in the central of these objects is linked to their formation region. Comparison process. Previous observations indicate that with simulations the frequency of multiplicity declines from suggests that the gap around 23 AU could be around 65% (for solar-type stars) to 10–30% cleared by a planet of (for the slightly warmer and more massive L and T dwarfs). Does this trend continue to the mass about 0.2 MJupiter. Y dwarfs, or does it indicate only our obser- vational limits? Also, some Y dwarfs show a at a resolution of about 1.5 AU and detect spread of luminosity or otherwise seem over- structure. The observations show a gap lo- luminous. Are undetected companions the cated around 23 AU that is about 5 AU wide, explanation? Figure 15. suggesting the presence of a forming Limits on separation planet (Figure 14). and magnitude for a The researchers deduce the prop- binary companion to one of the Y dwarfs erties of the possible (proto)planet Opitz and colleagues comparing with simulations. They observed using GeMS/ !nd good agreement with a planet of GSAOI. An equal- mass 0.16 MJupiter located at 21 AU from brightness companion the star, about the distance of Uranus is ruled out to within from the Sun. Details of the di"er- about 0.5 AU (0.04 ences between the model and obser- arcsecond), and fainter companions are ruled vations suggest that more complex out at somewhat distributions of dust in the disk (radi- larger radii. ally and vertically) may be relevant.

28 GeminiFocus January 2017 | 2016 Year in Review A Supermassive Black Hole Figure 16. That Wasn’t So Massive GMOS-South image of the center of the One sign of an extreme supermassive black Abell 85 galaxy cluster, hole at a galaxy’s core is a light de!cit — the which shows that the consequence of stars ejected from the central brightest cluster galaxy region. The brightest cluster galaxy of Abell at the center does 85 had been identi!ed as such an example, not contain the most massive known black claimed to host one of the most massive black hole in the Universe, holes ever detected in the Universe at around contrary to previous 11 10 MSun. estimates. Juan Madrid, then a Science Fellow at Gemini South, along with Carlos Donzelli (Observato- rio Astronómico de Córdoba, Argentina), used images obtained with the Gemini Multi-Ob- Daniela Opitz (University of New South Wales, ject Spectrograph (GMOS) on Gemini South Australia) and colleagues used the !ne spa- (Figure 16) to probe the galaxy’s center and tial resolution of the Gemini Multi-conjugate demonstrate that the black hole’s mass is not adaptive optics System (GeMS) and the Gem- so extreme. Rather than a de!cit, data from ini South Adaptive Optics Imager (GSAOI) to their Director’s Discretionary Time program begin to answer these questions, examining show the strong nuclear emission in the cen- a small sample of !ve Y dwarfs. The delivered tral kiloparsec as a light excess that may be Full-Width at Half-Maximum was ~0.1arcsec- due to a nuclear stellar disk. The observations ond and the limiting angular separation was were very short, only seven minutes. The key around 0.04 arcsecond. Although the obser- to the measurement was the spatial resolu- vations were su$ciently sensitive to detect tion to probe the innermost arcsecond. More companions of roughly equal mass at separa- information about this work is posted at the tions of 0.5–1.9 astronomical units (AU), they Gemini website, and full results are published did not !nd any evidence for binaries. Figure in The Astrophysical Journal. 15 shows the limits on separation and bright- ness for a binary companion to one of the Y dwarfs studied. The Fastest Quasar At least one of the sources had previously Ultraviolet Wind been identi!ed as “overluminous.” The pres- Quasar winds may be fundamental to the ence of clouds in the atmosphere, rather than growth of black holes and the evolution of a companion, may account for the excess lu- galaxies, being an intimate part of the feed- minosity. The few cases observed here are a back mechanism that regulates black holes good start, not a de!nitive determination of and stellar growth over cosmic time. Jesse the general trends. They do point to the ex- Rogerson (York University, Canada) and col- treme scenarios (separations less than 1 AU laborators have discovered an extreme exam- and extremely faint sources) that may arise in ple, the fastest ultraviolet wind, whose veloc- cases of Y dwarf binaries. This work is featured ity approaches 20% of the speed of light. on the Gemini website, and complete results appear in The Astrophysical Journal. The researchers originally used the Sloan Digi- tal Sky Survey to !nd quasars that show new broad absorption line troughs. Further obser-

January 2017 | 2016 Year in Review GeminiFocus 29 Figure 17. Three GMOS (North and South) spectra obtained at different times of the z =2.47 quasar J0230 show the variability of the absorption features, especially the CIV near rest-frame wavelength 1550 Å. The spectra have been normalized based on measurements in the shaded regions. vations using the Gemini Multi-Object Spec- trograph (GMOS) at both Gemini North and Gemini South show spectral changes over time in this case. At a redshift of z = 2.47, the galaxy’s rest-frame ultraviolet emission ap- pears at optical wavelengths, and broad CIV absorption is the key feature the team traced.

This exceptional example, called SDSS J023011.28 + 005913.6 or J0230 for short, is also interesting in showing a second strong component, with an out#ow velocity around 40,000 kilometers per second. The multiple observations of the quasar at various times show variability (on timescales as short as 10 days in the quasar rest frame; Figure 17) and enable the team to rule out some simple models of bulk motion. Instead, they show that some more complex geometric con!gu- rations are consistent with the observations — namely a “crossing disk” model (of a circular cloud that crosses a circular emitting region) and “#ow tube” (where a spatially extended absorbing region passes in front of the emit- ting region) for the faster and slower out#ows, respectively.

Continued study of the larger sample of about 100 candidates may reveal more systematic characteristics of the broad absorption fea- tures and their origin. This work is featured on the Gemini website, and full results are published in Monthly Notices of the Royal As- tronomical Society (viewable here).

30 GeminiFocus January 2017 | 2016 Year in Review Gemini sta! contributions News for Users During 2016 much happened at Gemini of relevance to our user community. What follows is a compilation of news, updates, and information of interest to Gemini’s users from the past 12 months.

January 2017

Base Facility Operations Begin at Gemini South Since late 2015, the Observatory has operated Gemini North at night from its Hilo Base Facil- Figure 1. ity with no sta" at the telescope facility on Maunakea. Gemini South has now followed suit; Javier Fuentes (left) as of November the Base Facility Operations (BFO) project began full remote operations in and Joy Chavez (right) La Serena, Chile. As promised in the January 2016 issue of GeminiFocus, in the interest of operating Gemini South e$ciency we copied much of the Gemini North project and pasted it into place at Gemini from the La Serena Base South, making this task as straightforward as possible. Along the way we made one or two Facility on November 14, locally-speci!c amendments and some minor improvements. 2016. Prior to November, we had already operated in “Base” mode with night sta" at the summit of Cerro Pachón for more than two months — progressively con!ning them to the control room as we added more and more monitor- ing capabilities and re- mote control options to the summit systems. On November 14th we were ready as planned, and the nighttime sta" carried out

January 2017 | 2016 Year in Review GeminiFocus 31 the !rst night of observing entirely from the Gemini Prepares for the Large La Serena Base Facility (Figure 1). Synoptic Survey Era There are two instrument exceptions to BFO Gemini is and will likely be a key facility for from La Serena: 1) the Gemini Multi-conju- following up interesting targets discovered in gate adaptive optics System/Gemini South large, time-domain surveys. We are currently Adaptive Optics Imager, for which we antici- working hard to prepare Gemini for the era of pate a new laser delivery in 2017 (and there- massive synoptic surveys such as the Zwicky fore we deferred the BFO safety interlock Transient Facility (ZTF) and the Large Synop- work until that new system is in place); and tic Survey Telescope (LSST). New instrument 2) the visiting instrument Phoenix, for which development at Gemini, such as the Gemini at least one subsystem required manual in- High-resolution Optical SpecTrograph (and tervention (and therefore was run from the especially Gen 4#3), will provide the needed summit in December 2016). spectroscopic capabilities. We are also plan- ning to improve the software and systems for handling a larger volume of Target-of-Op- portunity triggers. In an e"ort to better align ourselves and coordinate with the rest of the community, we have been participating in planning exercises (such as the Maximizing Science in the Era of LSST workshop) and dis- cussing the development of prototype Tar- get and Observation Manager systems with the National Optical Astronomy Observatory and the Las Cumbres Observatory. The com- munity should also begin to think about oth- er observing modes and strategies for using Gemini in the coming decade. Please contact Bryan Miller ([email protected]) for more in- Figure 2. Visiting Instruments formation, especially if you are interested in The Phoenix near-infrared The increase in visiting instruments at Gem- participating in these e"orts. spectrometer during its ini continues. Both Phoenix (Figure 2) and run as a visitor instrument the Di"erential Speckle Survey Instrument at Gemini South. (DSSI) spent time on Gemini South in 2016A, Making the Most of Poor and Phoenix returned to Chile in December. Weather Nights Phoenix su"ered very badly from the dread- Clouds and poor seeing can frustrate any ful weather in Chile in 2016A, but as this issue astronomer on a classical observing night. goes to press, the weather at Gemini South One of the main strengths of Gemini’s queue has improved. In 2017A both DSSI and Phoe- observing is that your program is observed nix return to Gemini South, while the Texas in the conditions it requires. While users Echelon Cross Echelle Spectrograph (TEXES) of Gemini North and South may not need mid-infrared instrument visits Gemini North. to worry much about bad weather nights, We look forward to even more visiting instru- less-than-ideal conditions can occur when ments at Gemini in the near future. To learn simply no targets exist in the regular queue more about our visitor instrument program, programs to observe. Even if that happens, view Gemini’s Visitor Instrument page here. Gemini rises to the occasion and makes the

32 GeminiFocus January 2017 | 2016 Year in Review most of the night by observing Band 4 or October 2016 Poor Weather proposals (if available). The “Super Seeing” (LGS+P1) Figure 3 (left). Band 4 programs can be submitted at any Mode This image is a time during the semester and are most wel- screenshot taken from In 2012, Gemini commissioned a new ob- come during periods of bad weather (see the UH88 camera serving mode for ALTAIR’s Laser Guide Star the following News for Users item). If you pointed at the Gemini system (known as LGS + P1), which added have a science case with bright targets that North telescope, dated the option of using a peripheral wavefront can handle Cloud Cover = 70% and above (or Monday, December sensor (PWFS1 or P1) for the Natural Guide any), any Image Quality, and any Water Va- 19, 2016. Star tip-tilt focus measurement. This mode por (with no restriction on Sky Background does not provide di"raction-limited reso- Figure 4 (right). — or any Cloud Cover and Water Vapor (with lution, but instead gives “Super Seeing” by An image taken from no restriction on Image Quality and Sky reducing the natural seeing point spread Hilo on December Background) — then consider submitting a function Full-Width at Half-Maximum (PSF 19, 2016, of a snowy Band 4/Poor Weather program today. More FWHM) by a factor of 2-3. The major ben- Maunakea. details on the proposal submission process e!t of this seeing-improver mode is that it Image credit: can be found at this link. increases the LGS sky coverage to almost Joy Pollard 100%. While the limiting magnitude of P1 Winter Blasts Maunakea is R = ~ 14 (less than the R = < 17 magnitude The tilt of our planet’s axis has once again for the conventional LGS mode), this is more delivered an extended period of weath- Figure 5. er not conducive to astronomical ob- Comparison of estimated serving on Maunakea. Starting in late sky coverage for LGS+P1 November a series of fronts, troughs, (red) compared with conventional LGS (black). and low-pressure systems have pro- Note that sky coverage duced overcast skies, wind, and signi!- refers to the percentage cant snow, (with drifting) at the Gemini of sky with guide stars North site (Figures 3 and 4). In the one above elevation 40˚ at month period from mid-November until Gemini North. mid-December,16 nights were entirely lost to weather, and an additional four were more than half lost. Overall, dur- ing this period we have only managed to obtain science for about one-third of the available time. As this issue goes to press the weather is improving! January 2017 | 2016 Year in Review GeminiFocus 33 than o"set by P1’s much larger patrol !eld. Gemini North Shutdown Figure 5 shows the predicted sky cover- Gemini North had an unscheduled shut- age as a function of galactic latitude for the down from August 10-31 to remedy a bro- LGS + P1 con!guration (red) compared with ken bearing in one of the drive boxes on the conventional LGS mode (black). the lower shutter (which is also responsible Currently, LGS + P1 has been commissioned for deploying the wind blind during high with the Near-InfraRed Imager and spec- wind conditions; Figures 6-7). This drive trometer (NIRI) and Near-infrared Integral box failed in late July, resulting in the lower Field Spectrometer (NIFS); it is also being of- shutter being pinned in an inconveniently fered in shared-risk mode with the Gemini high position until a shutdown was pos- Figure 6. Near-InfraRed Spectrometer (GNIRS). It is im- sible. Favorable observing conditions near Hoisting a 150-pound portant to understand that signi!cant #exure the end of 2016A allowed us to do a signi!- drive motor, using one issues remain, which limit the use of LGS + P1 cant amount of 2016B observing before the of the largest cranes on targets that are not visible during acqui- semester started. This then allowed us to available on the island sition; this mode also signi!cantly limits the take advantage of a relatively light queue of Hawai‘i. amount of time that a target can remain in at this early stage in the semester and initi- ate an unplanned shutdown to work on the Figure 7. a spectroscopic slit. In fact, for spectroscopy, lower shutter, as well as perform work that The Gemini North the Super Seeing mode requires that a con- bottom shutter’s tinuum source be visible (signal-to-noise ra- was originally scheduled for a planned shut- broken drive box, with tio > 1 per spectral element) somewhere in down in October. That work included trou- a segment of the drive the science frame for typical exposure times bleshooting on the Acquisition and Guiding chain showing at left. (~ 15 minutes). In addition, we cannot sup- system, maintenance on the Gemini Multi- port blind o"setting at this Object Spectrograph (GMOS), and a !lter ex- time. Since this is a work-in- change on the Near-InfraRed Imager (NIRI). progress, part of the mode’s Thanks to this solution we plan to be observ- shared risk nature includes ing on a normal schedule throughout Octo- the possibility that we may ber. A GRACES run had been scheduled dur- not be able to implement ing the unplanned August shutdown, but an the #exure model, or that the agreement with the Canada-France-Hawai‘i magnitude of #exure may Telescope allowed us to continue with these be larger or more di$cult to programs following the shutdown. correct than expected. — Andy Adamson and Steve Hardash Nevertheless the Super See- ing mode has proven to Gemini South Shutdown be very useful for conven- Gemini South was shut down for two working tional LGS mode programs weeks from August 16-25, to carry out annual for which the availability of maintenance on the Acquisition and Guid- guide stars was an issue; in ance (A&G) unit (Figure 8) and, speci!cally, to about 99% of the cases, the address issues with the Gemini Multi-Object Super Seeing mode was Spectrograph (GMOS) on-instrument wave- there to help by reducing the front sensor, which had become very noisy natural seeing PSF FWHM by and a"ected our ability to guide on faint stars at least a factor of two. (Figure 9). — Marie Lemoine-Busserolle — Andy Adamson and Michiel van der Hoeven

34 GeminiFocus January 2017 | 2016 Year in Review GMOS-S Photometric Figure 8. Alejandro Gutierrez Standard Utilities and Hector Swett Have you ever received images (Senior Electronics of standard star !elds from the Technician and Gemini Multi-Object Spectro- Electronics Engineer, graph at Gemini South (GMOS-S) respectively) work on and struggled to work out which one layer of the A&G unit’s “cake” during stars are the actual #ux standards? the Gemini South Now, help is at hand, thanks to the shutdown. Australian National Gemini O$ce and students from Macquarie Uni- versity in Sydney. Figure 9. GMOS-S on-instrument For each photometric night on wavefront sensor which GMOS-S imaging data are images from before taken, the Gemini South queue (left) and after (right) observer also observes at least the Gemini South one standard star !eld. These stan- shutdown. Each frame dard star !elds are taken from a shows the image of list of 45 !elds (covering the range a star from the four of right ascension and declina- wavefront-sensor tion) drawn from the (unpublished) catalog The !nders are available (view here), which subapertures. The image at right was taken of J. Allyn Smith et al.’s Southern Hemisphere give for each !eld an OT view of the !eld in very poor seeing, but u’g’r’i’z’ Standard Stars. However, the task (clickable for higher resolution) and tables of the difference in quality of identifying which stars from this catalog magnitudes for each standard star (Figure 10). of readout is clear. The are within the GMOS !eld-of-view has, until While this utility has been available via the “noise” in the worst parts now, been tedious. GMOS photometric standards page for of the “before” image is Fortunately, Macquarie University operates some time, it probably hasn’t received the 150 analog-to-digital units a unique program known as PACE (Profes- attention it deserves. In due course, e"orts (ADU) or more, although it was the systematic sional And Community Engagement), which such as the SkyMapper Southern Sky Survey pattern which really caused o"ers opportunities for their undergraduate and its shallow photometric survey should problems with guiding. students to make long-lasting contributions make deriving photometric zero-points Now we consistently see to the community, while integrat- only 10 - 12 ADU of truly ing practical experience into their random noise. degree. In 2014 PACE students Corine Brown and Dylan Harrison — under the supervision of the International Telescopes Support O$ce (ITSO) sta" Stuart Ryder and Figure 10. Richard McDermid — conducted a project to construct !nding charts Finding chart for the GMOS-S standard star field for all 45 !elds using the Gemini NGC 458-AB, a star cluster Observing Tool (OT), complete with in the Small Magellanic magnitudes for each standard star Cloud, based on the OT present in the GMOS !eld-of-view. Position Editor display.

January 2017 | 2016 Year in Review GeminiFocus 35 Figure 11. from separate standard star observations July 2016 A color mosaic of a redundant (as every GMOS !eld will con- region of the Pyxis tain multiple sources with catalogued u’, g’, A Month to Forget globular cluster, r’, i’ and z’ magnitudes), but in the interim we May 2016 may have been the worst month produced from HST trust that the community will !nd this a use- ever for weather at Gemini South on Cerro F606W and F814W ful resource. Pachón in Chile. In an average year, May is images and a stack of the !rst of !ve “bad” months, with weather GSAOI H-band frames. Disco-Stu — GSAOI Image loss usually on the order of 30% (see chart Disco-Stu was provided on page 41). By contrast, in May 2016, we with one of the HST Reduction Simpli!ed had 16 nights during which we observed images and a source Gemini has announced the release of a new catalog constructed from nothing at all, and a further seven during standalone software package. Called Disco- that image (culled of which we observed for less than three hours; Stu (DIStortion COrrection and STacking faint sources and objects in fact, weather interrupted observations ev- outside the GSAOI field- Utility), it is designed to help with the analy- ery night to some degree during this period. of-view) but no further sis of images taken with the Gemini South An extended and unusually poor weather guidance was required. Adaptive Optics Imager (GSAOI). Disco-Stu takes images that period started in April and lasted well into have been reduced June, with mainly high clouds as seen in with the Gemini Im- Figure 12 (but resulting in surprisingly little age Reduction and precipitation). This could be an e"ect of the Analysis Facility pack- strong El Niño event that is gradually ending. age for GSAOI and Given that, on average, weather losses on aligns them by match- Cerro Pachón peak in June and July, we can ing sources with the only hope that 2016 isn’t “average,” and that aid of a lookup table we will have better observing conditions in that maps the instru- the following months. Obviously, the impact ment’s static distor- on observations has been signi!cant. Bad tion. Stacking is then weather wiped out most of the Phoenix vis- performed with bad iting instrument run and greatly hindered pixel rejection and, if desired, inverse-vari- ance weighting. The astrometry can be tied to an external source catalog, and the output image can be made to share the world coordinate system of an- other image. Performing both these steps results in an image that is perfectly aligned with an existing image, either taken with a Figure 12. di"erent instrument, or with GSAOI at a dif- Gemini South’s shutters ferent epoch (Figure 11). remained closed for most of May 2016, due to Disco-Stu is written in Python and requires persistent poor weather. the NumPy and AstroPy packages (which Image credit: are part of the Ureka release). SExtractor is Sandra Romero, Gemini also required for normal operation, although source catalogs can be prepared separately. — Chris Simpson 36 GeminiFocus January 2017 | 2016 Year in Review our progress on the many programs sched- all mechanisms, which raised some addi- uled for this semester. tional suspicions during the movement of the Multi-Object Spectroscopy (MOS) wheel The good news is that, as reported in the (Figure 14). Further inspection indicated sig- April 2016 issue of GeminiFocus, we have ni!cant wear in some of the ball bearings, begun adjusting the queue !lling to ac- so all were replaced. The team then reas- count for the typical pattern of bad weather sembled and successfully tested the entire at Gemini South. So, fortunately, the queue mechanism. was not overloaded in May as it had been in the past. Finally, the instrument was cooled down, !rst with liquid nitrogen in the lab, before we connected it to the helium compres- FLAMINGOS-2 sors on the telescope. We returned FLAMIN- Stand-down Completed GOS-2 to the telescope, tested it during the In May, we removed FLAMINGOS-2 from night, and cleared it for scienti!c operation. the Gemini South telescope for a preventa- With this success, a large period of inten- Figure 13 (left). tive maintenance stand-down. Moving to sive work came to an end. The instrument The new camera cold dedicated instrument stand-downs ensures should bene!t from reliable operations for head (green mechanism, that key resources and the laboratory envi- the coming semesters, and we can now be- at bottom). Above it is ronment are available without competing gin working on the commissioning of the the gate valve baffle, against other important tasks. This has been MOS observing mode. which is employed during an issue during other single annual tele- MOS mask swaps due to previous thermal scope shutdowns. Repairing the Gemini North background issues. A large team of engineers, technicians, and Wind Blind Image credit: Gabriel science sta" completed a variety of tasks. Perez/Gemini/AURA Both Gemini domes are equipped with a First they replaced the instrument’s three three-segment wind blind, which is de- coldheads (one is shown in Figure 13), which Figure 14 (right). ployed by moving the lower shutter to shield were approaching the end of their lifetime; The MOS wheel (larger the telescope structure from wind coming indeed, the coldheads should keep the de- segmented black wheel, from the direction of the open slit (Figure tector at a selectable temperature, but we in front, showing slots for 15). Gemini North’s wind blind has caused have seen the temperatures gradually in- MOS masks) and Dekker concern since early 2015, when we found wheel (smaller black creasing. Replacing coldheads might sound excess wear on the track and roller system wheel, behind). easy, but accessing and replacing them re- during regular maintenance. Considered a Image credit: Gabriel quires dismantling the instrument. serious problem, we disconnected it in the Perez/Gemini/AURA Another outstanding issue was addressed by !xing the On-In- strument WaveFront Sensor used to mea- sure distortions at the instrument imaging plane. Careful testing and analysis revealed an electronics problem, which we resolved. We also thoroughly tested

January 2017 | 2016 Year in Review GeminiFocus 37 continue for two weeks. Observers cannot use the wind blind at night throughout this period. We’ll report on the outcome in a fu- ture edition of GeminiFocus. The equivalent system at Gemini South has been inspected and shows no signs of similar problems, how- ever, the process is being documented by sta" to assist on future possible work.

DR User Forum The Gemini Data Reduction (DR) User Fo- Figure 15. second half of 2015 (when historically winds rum is a platform created for trading ideas, The Gemini wind blind are lowest) to decrease run time and wear. scripts, and best practices. Anyone is invited design drawings. Left: We reconnected the wind blind in Novem- to ask questions or trigger discussions about blind segments all ber, to provide shielding during this more data reduction, processes, and strategies. stowed, with the guide The DR Forum permits immediate di"usion tracks above them windy period, but decreased its maximum to a broad audience. It allows users to have following the shape of travel from 60 to 55 degrees. With Base Facil- the attention of many experts that would the dome arch. Right: ity Operations in the North now implement- detail of the segments; ed, we are able to focus on this problem and otherwise be di$cult to contact. The Forum the largest is 5.5 meters plans are now in place to work on it over the also o"ers a di"erent, more direct, channel (18 feet) high. Northern Hemisphere summer. The project to contact Gemini sta", instrument builders, involves replacing all tracks guiding the wind and experienced researchers. blind and all guide roller assemblies, and per- Please visit, search, read, and contribute to forming repairs on any other damage found. the Gemini DR Forum. If you would like a new This is a major job, requiring three di"er- topic to be covered, simply register (if you ent pieces of heavy equipment, including a have not already) and add it to the discus- 120-ton mobile crane. We have requested sions. Each new post will receive attention and received approval to hire and use that promptly. equipment on Maunakea. Work will start im- For additional questions or comments, please mediately after the July 4th holiday, and will contact us at: [email protected]

Is the DR Forum for you? The answer is probably yes, but especially if: r You are performing optical or infrared data reduction for the !rst time: — Because you are working on your thesis — Because you are expanding your work to include wavelength bands or instruments with which you are not particularly familiar.

r You are adept with optical and infrared reduction but would like to share best practices with your colleagues so they can utilize good habits, which will lead to clearer and more accurate descriptions of their data reduction methods.

r You are simply facing a speci!c issue with your current data reduction, and you want to share your questions or solutions with a broad community of astronomers.

38 GeminiFocus January 2017 | 2016 Year in Review 2016B Observing Tool The 2016B Gemini Observing Tool (OT) was released on June 3, 2016. Install- ers for Mac, Linux, and Windows may be downloaded from the OT webpage. This version of the OT has several sig- ni!cant improvements to make pre- paring Gemini observations easier.

The !rst big change is the removal of the button to trigger the Automatic Guide Star (AGS) search. Guide star queries are now performed automati- cally in the background whenever us- ers create or modify observations. This new feature works with all instruments and will update the guide star whenever an mester for planning purposes. For accurate Figure 16. observation, or observing conditions, are visualization in the Position Editor and opti- Position Editor showing updated. It will also automatically select the mal guide star selection, this is augmented the position of Saturn’s best guide star when the nighttime observer by ~5-minute resolution data for the sched- moon Titan (green line) updates the time of non-sidereal or parallac- uled night observation. The Observing Da- with the start of the observation indicated tic angle observations. If you don’t like the tabase independently keeps track of active by the yellow circle. automatically chosen guide star you may non-sidereal observations and downloads use the Catalog Query Tool (new in 2016A) high (1-minute sampling) resolution eph- to manually select your preferred one. Manu- emerides the day before an observation ally selected guide stars (and guide stars might be scheduled. from previous semesters) are displayed in a New plotting capabilities in the Position Edi- “Manual” target group, and the auto-guide tor accompany these infrastructure changes, star system will not modify them. displaying the path of non-sidereal targets The second big change is an overhaul of throughout the semester. The red line in Fig- non-sidereal target support, which is fun- ure 16 shows the orbit of Titan as seen from damentally di"erent in the 2016B OT. The Maunakea in March-April 2016. The yellow 2016A OT handled non-sidereal targets us- circle in the center marks the start of an ob- ing a mix of data — Minor Planet Center and servation, and the green line segment shows Jet Propulsion Laboratory (JPL) minor planet the position of Titan during the scheduled orbital elements, a selectable list of the eight observation. major planets, and manually generated eph- There were many smaller improvements and emerides — which can be confusing and bug-!xes too numerous to mention. Please cause errors when preparing observations. see the OT Release Notes for more details, The 2016B OT supports all non-sidereal tar- and for more news on upcoming software gets using automatically generated and changes please follow the Gemini Science updated ephemerides from JPL HORIZONS. Software Blog. When a user creates an observation the OT will download a low (~6-hour sampling) resolution ephemeris covering the entire se-

January 2017 | 2016 Year in Review GeminiFocus 39 April 2016 How the Queue Responds to lenges. Here we look at an exceptional se- Adversity mester (one with good conditions and more science time than originally planned) and a bad semester (a"ected by weather and tech- All observatories attempt to complete sci- nical problems) and summarize the results. ence programs against a variety of compet- ing factors: weather, equipment failures, Recent Challenges earthquakes, etc. Queue scheduling attempts to preferentially complete programs blessed Figure 17 shows the average program com- with the highest science ranking by the Time pletion rate of Bands 1-3 over the past !ve Allocation Committees (TACs), whatever the years. Many factors are at play in these plots, competing factors put in the way. but we can single out examples of exception- Weather losses, commissionings, earth- ally good and exceptionally bad semesters. quakes, and other events in recent years For instance, Semester 2012A at Gemini have given us quite a roller-coaster ride, and South was particularly good, because more it’s interesting to see how queue scheduling science time became available when the Ob- (recently the largest part of the Gemini sci- servatory cancelled planned commissioning ence program) has responded to these chal- work. The most recent semesters at Gemini Figure 17. Average program completion across Bands 1, 2, and 3 (blue, orange, and grey, respectively), for all semesters since 2010A. Top: Gemini North. Bottom: Gemini South.

40 GeminiFocus January 2017 | 2016 Year in Review South have been chal- lenging, especially 2015B, which we discuss later). Semester 2014A at Gemini North was unusually poor, as bad weather and dome shutter failures hit us hard; but we recovered and are now back at roughly av- erage performance com- pared to the last !ve years.

The two charts in Figure 18 show histograms of queue program completion at Gemini South 2012A and Gemini North 2014A.

The very sparse tail of programs below the 100%-complete bin in the “exceptional” semester compares with large num- bers of programs ending at better. As you can see in Figure 18, in recent Figure 18. 90% and below in the “bad” semester. Numer- semesters, Band 3 has done well relative to In 10% bins, the fraction ous programs were not started at all in 2014A the others at Gemini South; again, this is a of programs ending at Gemini North. symptom of weather adversity. the semester at a given Note that the queue preferentially protects completeness level. Top: an unusually good Band 1 observations in a “bad” semester, as Addressing Weather Loss at it should. In the “exceptional” semester at semester (Gemini South Gemini South the Band 1 completion ex- Gemini South 2012A). Bottom: an unusually bad semester ceeded that of Band 2, which in turn exceed- Weather conditions at Gemini South repeat (Gemini North 2014A). ed that of Band 3. In a “normal” semester themselves fairly regularly across each se- (neither exceptional nor terrible) results lie mester. In the past we didn’t make any allow- Figure 19. somewhere between these Percentage of time extremes, with Band 1 com- lost to weather at pletion higher than that in Gemini South. This pattern is quite the other two bands. reproducible from While Band 2 completion year to year. We now usually exceeds that in take better account of it in the time Band 3 during a “normal” allocation process; we semester, it is a signature of no longer overload bad weather that in some the mid-year months semesters Band 3, in which (May-September), and programs can typically take allow more programs poorer conditions, does into the southern summer time. January 2017 | 2016 Year in Review GeminiFocus 41 September 2015; the Gem- ini Planet Imager (GPI) still ramping up; and many pro- grams either lost complete- ly to weather, or executed under marginal conditions. Based on the discussion above, we would therefore expect a signi!cant hit on programs in all Bands, with Band 3 (able to take the Figure 20. ance for that. Recently, we’ve made a change worst conditions, and there- Program completion to the way we !ll the queue for Gemini South. fore not containing any GPI or GeMS pro- in 2015B at Gemini Figure 19 shows a repetitive !ve-year pattern grams) performing reasonably well. That’s South. Note the of weather losses at Gemini South; because borne out by the results shown in Figure 20: significant numbers of we !lled the queue each month as if the a signi!cant number of GPI programs were unstarted programs not attempted at all, hardly any GeMS pro- (driven by instrument weather loss was uniform (and it wasn’t), we grams started, and many programs ended unavailability), and forced ourselves to battle the elements at the the excess of Band worst times of the year. In the 2016A TAC pro- up in the “tail” of completions below 100%. 3 programs in the cess, we adjusted the way we !ll the queue: 100%-complete bin we no longer overload May-September, and (a signature of bad GPI and Telescope Vibration allow more programs into the southern sum- weather). In late 2013, early commissioning tests of mer months. We’ll see how it goes now that the Gemini Planet Imager (GPI) on the Gem- we’re into the semester itself. ini South telescope (Figure 21) revealed a strong oscillation in the corrected wave- 2015B: Major Challenges at front, similar to defocus. The 60 Hz oscilla- Gemini South tion frequency pointed to the GPI Stirling Figure 21. cycle cryocoolers (which run at 60 Hz) as the As mentioned, Gemini South has had some GPI (center) installed cause. But we did not understand the mech- challenging semesters of late. Semester on the up-looking anism that disturbed the optical wavefront. port of Gemini South. 2015B, for instance, had plenty of adversity After !tting the telescope optics with accel- FLAMINGOS-2 is at to go around: the Gemini Multi-conjugate erometers, a team of Gemini scientists and top, and GMOS-S is at adaptive optics System (GeMS) out of ac- engineers detected the oscillations in the bottom. tion due to a major earthquake that struck in primary mirror (M1). The center of M1 was vibrating relative to the outer edge with a peak-to-peak amplitude of 840 nanometers (nm) — su$cient to cause a focus-like shift of about 1 millimeter at the GPI focus. The vibration completely disappeared when we turned o" the GPI cryocoolers.

To improve the delivered wavefront, the GPI team !rst developed a software !lter to mea- sure the 60 Hz focus oscillations. They then applied a correction signal to GPI’s adaptive optics. The !lter improved GPI’s performance

42 GeminiFocus January 2017 | 2016 Year in Review Figure 22. to a satisfactory level, but the 60 Hz vibra- Close-up of GPI tions remained in M1, potentially a"ecting attached to the other science instruments. Therefore, in mid- instrument support 2015, Gemini upgraded the GPI cryocooler cube (white, at top). controller to a new model — one with an ac- Vibrations from the tive damping system that measures the cryo- instrument’s cold heads coupled very cooler’s acceleration and applies a counter- efficiently into the acting one to dampen the vibrations at their cube and then into source (Figure 22). Measurements with GPI the mirror cell. indicate that the new system reduces the 60 Hz defocus residual wavefront errors from Australia’s Partnership in about 50 nm root-mean-square (rms) to as Gemini: A Retrospective low as 1 nm rms — a factor of 50 reduction! December 31, 2015, marked the end of Work on vibrations in GPI is part of a long- Australia’s time as a full member in the term program to characterize and reduce international Gemini Partnership. Stuart vibration e"ects on both Gemini telescopes. Ryder, Head of the Australian Gemini Over the next two years, we plan to install a O(ce (AusGO), re"ects on Australia’s common accelerometer system on both tele- participation as a Partner over almost scopes to permit continuous monitoring of two decades. vibration levels. Australia joined Gemini in 1998, with the !rst time allocations made in Semester 2001A. Early Use of the Gemini Over the next 30 semesters, the Australian Observatory Archive Time Allocation Committee received a to- Early use of the new Cloud-based Gemini tal of 739 Gemini proposals. Of these, 440 Observatory Archive has been healthy. Here were allocated queue time, and a further 25 are some initial statistics as of April 2, 2016. were allocated classical nights on Gemini (or Subaru via the time exchange program). t
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UP- queue mode, almost two-thirds of these tal of 45,000 archive searches and down- programs got 80% or more of the data they loaded 550 GB in 117,000 !les. We’re cur- requested under the required conditions. rently seeing about 1,750 archive searches and about 30 GB (compressed) downloads Following are some notable per week. Australian contributions to Gemini:

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r Development of the Near-infrared Integral archive, a total of 8.6 TB (compressed), and Field Spectrograph (NIFS) and the Gemini 29 TB ( uncompressed) FITS data. South Adaptive Optics Imager (GSAOI), two of the more productive and reliable Finally, don’t forget that in order to access instruments on the Gemini telescopes. proprietary data from your program you will need to register your program ID with your r The Australian Gemini Undergraduate archive user account. See this paragraph on Summer Studentship (AGUSS) program. the help page for further instructions. Since 2006, the program has sponsored 23

January 2017 | 2016 Year in Review GeminiFocus 43 Australian-a$liated author, re#ecting the collaborative nature of many of the pro- grams’ allocated time. This works out at one Gemini paper with Australian involvement for every eight hours of Gemini time used. Gemini data from Australia has contributed to the PhD theses of 45 students at Austra- lian institutions.

Australian Gemini Cosmic Poll Throughout Australia’s membership in the Gemini Partnership, AusGO ran an annual competition in which school students and amateur astronomers competed to de!ne an observation to be done in queue time. New AusGO sta" member Elaina Hyde took the 2015 Australian Gemini Image Contest in a new direction by transforming it into Figure 23. Australian undergraduate students, who the “Australian Gemini Cosmic Poll.” Rather Gemini South image spent a summer at Gemini South carrying than requiring high school students or of NGC 3310 obtained out research projects with Gemini sta" and amateur astronomers to propose suitable as a result of the becoming excellent ambassadors for Gem- targets as in earlier contests, the entire Aus- Australian Gemini ini within the Australian community. tralian public were invited to vote on one of Cosmic Poll in 2015. four categories of objects to be observed: NGC 3310 is a grand r The Australian Gemini School and Amateur an individual galaxy, a galaxy pair, a plan- design galaxy about Astronomy Contests. Since 2009, these 50 million light etary nebula, or another type of nebula. contests have inspired school students years distant that In a spirit of friendly competition, each likely collided with a (and more recently amateur astronomers) smaller galaxy about to suggest targets to image with GMOS-S, AusGO sta" member pitched their favorite 100 million years ago resulting in some awe-inspiring color pic- class of object in a short video. The science — warping its disk tures of galaxies and nebulae. and media technology platform hosted the and inciting bursts of poll, and it received more than 100 votes star formation (the r A Joint Proposals Database. Established in the space of two weeks; in the end, the pink regions in the and operated by the Australian Gemini Of- “individual galaxy” category came out on galaxy’s arms). !ce (AusGO, now hosted by Gemini), this top, and the selected target was NGC 3310. database enables the sharing of one tech- While the observations were made active nical assessment for joint proposals, there- in the Gemini queue, Elaina coordinated a by improving collaboration and e$ciency “Live from Gemini” video event with Peter across the Partnership. Michaud and André-Nicolas Chené, and r With the participation of Gemini sta", the posted regular updates to the AAO’s Face- AusGO ran two very successful Observation- book page and Twitter accounts. AusGO al Techniques workshops (in 2011 and 2014), released the !nal stunning image of NGC with a legacy of online talks and tutorials. 3310 (Figure 23) just before Christmas — a !tting way to mark the end of Australian us- Of the almost 1,800 Gemini papers in refer- age of Gemini’s queue mode. eed journals, about 15% have at least one

44 GeminiFocus January 2017 | 2016 Year in Review Gemini sta! contributions

On the Horizon Myriad advances in Gemini’s instrumentation and capabilities occurred in 2016. This review looks at these developments and what the future holds for Gemini’s instrumentation program.

January 2017 GeMS’ Next Generation Natural Guide Star Sensor: Making Progress GeMS, the Multi-conjugate adaptive optics System deployed at Gemini-South, has been in use for several years now, producing spectacular results with its capability to deliver di"raction-limited image quality over a !eld more than 1 arcminute wide. To achieve this performance GeMS uses !ve laser guide stars for high-order wavefront sensing, and up to three natural guide stars (NGS) for tip-tilt and plate scale modes sensing. However, opera- tion of GeMS is rather complex, principally due to technical issues. Recent technological developments have opened the possibility to improve the operational e$ciency drasti- cally (for instance, see page 47 of this issue to read about the new laser system being pro- cured). Here we report on developments to enhance the selection and performance of natural guide star tip-tilt sensing.

A key problem encountered in GeMS operation revolves around the acquisition of natural guide stars. The existing Natural Guide Star Wavefront Sensor (NGS WFS) used for tip-tilt sens- ing su"ers from low throughput, which severely reduces the number of stars that can be acquired, thereby diminishing the amount of sky coverage attainable by GeMS. Furthermore, the existing NGS WFS system uses three mechanical pickup probes, each of which can patrol the whole !eld. But these probes have only a very small !eld-of-view which, due to #exure and variable !eld distortions, sometimes makes it time consuming to acquire the stars.

Thanks to current state-of-the-art detector technology that has become available, these limitations can now be tackled. A key change is that rather than having three mechani-

January 2017 | 2016 Year in Review GeminiFocus 45 Figure 1. cal pickup probes patrolling the !eld to !nd tions. In a nutshell, NGS2 is composed of an Design drawing of the and track the guide stars, the future system optical system that re-images the focal plane Natural Guide Star will use an electron multiplying charge-cou- onto a high-speed electron multiplying CCD Next Generation Sensor pled device (CCD) detector that can image detector. In full-frame readout, the guide stars (NGS2) unit (shown in the whole !eld, allowing straightforward can be easily identi!ed. For tip-tilt sensing green) occupying one identi!cation of guide stars. only, small areas around the stars are read out corner of the Canopus at high speed. A dedicated central processing AO optical bench. Multiple regions of interest centered on the unit will determine the centroids and pass the guide stars can also be con!gured and read Figure 2. necessary information to the adaptive optics out at very high speed — up to 800 hertz The NGS2 unit, nearly (AO) real-time control system. with very low read noise. This new sensor fully integrated in the ANU laboratory. converts the existing delicate opto-me- The space constraint for the new NGS2 sys- At the bottom of the chanical arrangements of the guide probes tem, which needs to !t onto the existing AO image one can see two to a system that will essentially be software optical bench, is very demanding; the align- large fold mirrors that con!gurable and more robust. Its higher ef- ment tolerances and system integration are channel the light into !ciency is expected to improve the detec- challenging features, as well. Figure 1 shows the re-imaging optics. tion limit for natural guide stars by some 2.5 the design drawing of how NGS2 will just !t The large unit at the top magnitudes, which will result in a dramatic into a corner of the AO optical bench. Further- left houses the electron multiplying CCD improvement in sky coverage. more, the detector generates heat that has to be actively removed, so as not to a"ect the detector. In 2014, we secured funding from the Aus- Image credit: courtesy rest of the AO system. And !nally, one func- tralian Research Council for a proposal of the Australian tionality of the existing system — the focus led by the Australian National University National University sensing of the natural guide stars — cannot (ANU). This — to- be incorporated in the NGS2 design. There- gether with addi- fore, one of the existing peripheral wavefront tional funding from sensors will take over that function. Gemini, the Austra- lian Astronomical Very good progress has been made to date Observatory, and in the detector upgrade. Essentially the the Swinburne Uni- opto-mechanical system and the detector versity of Technol- system have been completed and are going ogy — opened the through the !nal stages of integration and possibility to design alignment at the ANU laboratories. Figure 2 and build this Natu- shows a recent picture of the NGS2 system ral Guide Star Next on the bench. Generation Sensor, The system is in a very advanced stage of or NGS2, in short development and currently undergoing (see Figures 1 and 2). the !nal stages of alignment. Figure 2 also We expect the new shows a recent picture of the built NGS2 NGS2 subsystem will module on the bench, ready for testing. become an integral Formal Acceptance Testing was successfully part of the Canopus carried out in early December. adaptive optics sys- Still, much work remains to be done. In par- tem, replacing the ticular, a signi!cant amount of software de- existing NGS unit velopment is pending while resources are with the minimum very tight. Also the integration of NGS2 into necessary modi!ca- Canopus will be a delicate activity and re- 46 GeminiFocus January 2017 | 2016 Year in Review quire extensive testing, during which time it livered hardware for the GMOS-N CCD instal- cannot be used for science. Hence planning lation. We also called on Tim Hardy (detector of this activity must be done with care. We engineer), who worked on the original set of have great expectations for this new natural GMOS-S Hamamatsu CCDs at the National guide star system and expect that NGS2 can Research Council of Canada-Herzberg, for be delivered to the Observatory during the additional support. As a result, we found and course of 2017. We intend to report on fur- corrected some issues with the controller ther progress in future issues of GeminiFocus. Digital Signal Processing code. We also de- Figure 3 (top left). — Rene Rutten veloped a more e$cient ground scheme for Emmanuel Chirre (left) the Astronomical Research Camera control- and Cristian Moreno ler to provide a more stable bias level and stand guard over the Gemini South Laser Guide Star lower readout noise of about 4e-. new Toptica laser. Facility News As we provide this report, the GMOS team Figure 4 (bottom left). On October 5-6, the Gemini South Laser continues to maintain schedule, having The Gemini South laser system being Guide Star Facility completed its Factory now completed the controller pre-installa- integrated at Toptica. The Acceptance Test (FAT) readiness review at tion Acceptance Testing in November (Fig- Toptica AG Photonics in Munich, Germany Electronics Cabinet (at ures 6 and 7). We also measured good read left) is connected to the (Figures 4 and 5). The actual FAT occurred noise and all functioning ampli!ers, and laser head without the between November 28–December 2 and found no signi!cant cosmetic concerns. The protective covers (at right) was successful; all the requirements met the installation of the new CCDs into GMOS-N is through the black fiber speci!cations established in the contract. scheduled to start by the !rst week of Feb- splice boxes (at center). Also, the Toptica team provided initial train- ruary 2017, with commissioning on-sky in Figure 5 (below). ing to Gemini South scientists and engineers mid March 2017. attending the FAT. The Toptica laser was The Gemini South laser cabinet just before shipped on December 2nd and arrived safely — Luc Boucher connecting to the laser at Cerro Pachón on December 13th head during the FAT (Figure 3). We plan post-shipping readiness review on Acceptance Testing (AT) in January October 5-6. 2017. During the post-shipping AT, Image credt: All three we will verify the laser survived the images by Manuel Lazo shipping, maintaining all function- ality at the speci!ed performance. We plan to start installing the la- ser’s subsystems at the telescope in May 2017, with commissioning on-sky in August 2017. — Manuel Lazo

Gemini Multi-Object Spectrograph CCDs Through an exhaustive amount of troubleshooting, the Gemi- ni Multi-Object Spectrograph (GMOS) upgrade team resolved the anomalies found in the as-de-

January 2017 | 2016 Year in Review GeminiFocus 47 Figure 6. Gemini High-resolution Optical The new Hamamatsu CCDs mounted and SpecTrograph (GHOST) aligned in the Focal Plane As we near the midpoint of the GHOST Array and ready to be project build phase, the build team contin- installed into the Test Cryostat to start pre- ues to receive parts from its suppliers, and installation Acceptance the assembly of the instrument and the Testing. Image credit: development of the software progresses John White on schedule. The team recently completed some veri!cations on the telescope at Gem- ini South.

In November 2016, engineers from the Aus- tralian Astronomical Observatory (AAO) and Gemini successfully veri!ed the align- ment of the Instrument Support Structure (ISS) mounting surface relative to the tele- Figure 7. scope optical axis. This was important to The first light (raw) check because any misalignment needed image of the new to be within tolerance to ensure that the Hamamatsu CCDs; GHOST system throughput is maintained. the 12 amplifiers The GHOST Cassegrain unit is designed to see light, and show be mounted directly on the ISS and both of no evidence of cosmetic defects. its integral !eld units are designed to proj- Image credit: ect the telescope pupil, which is coincident Luc Boucher with the secondary mirror, onto the !ber core of the !bers which connect with the spectrograph in the pier lab. The !bers are protected by an outer conduit, constitut- Figure 8. ing the optical cable assembly, running the AAO Engineer Vlad Churilov and the length between the telescope and pier lab. GHOST mock optical In October, other engineers from AAO and cable during testing Gemini ran some tests using a mock opti- in Chile. Image credit: David cal cable assembly to demonstrate how this Henderson cable would move, and to identify any po- tential problem areas, such as snagging, as the telescope changes positions (Figure 8). These tests resulted in some minor design tweaks, and an overall con!dence in the cable design. We expect the !rst delivery of GHOST subassemblies, Cassegrain unit, and cable assembly at Gemini South to occur in the fourth quarter of this year.

— David Henderson

48 GeminiFocus January 2017 | 2016 Year in Review October 2016 Gen 4#3 Instrument Development Gemini Observatory received four very good Gen 4#3 proposals before the Request for Proposals (RfP) deadline at the end of Au- gust. We then sent the proposals to an expert evaluation committee for assessment. Within two weeks, we received excellent feedback against the predetermined evaluation crite- ria. We held an evaluation committee meet- ing at AURA’s Center for Administration in Tucson, Arizona, on September 23rd, and the this instrument will bring long-desired ca- Figure 9. committee created a number of highly-val- pabilities at a high level of performance to GHOST expected ued recommendations in their report. Gemini South. At the June 2016 conference performance In addition, upon receiving the proposals, of the international society for optics and comparison against other current Gemini extracted information and sent a photonics (SPIE), held in Edinburgh, Scot- instruments in the land, several GHOST project team members short report for review by a subcommittee field today. of the Gemini Board of Directors. As stated in reported on the project’s status. the RfP, !nal selection is based on a number Andy Sheinis, Head of Instrumentation at of components, some outside the remit of the Australian Astronomical Observatory the evaluation committee, and these are the (AAO), which leads the multi-institution areas that the Board subcommittee is assess- team building GHOST, described the tech- ing. The Board subcommittee responded nical advances incorporated into the in- promptly, helping us to maintain our sched- strument. GHOST is designed to deliver R = ule in the early stages of the project. 50,000 and R= 75,000 spectroscopy for up to In October, Gemini will make a number of two objects simultaneously. GHOST uses a physical and virtual site visits to seek clari!- !ber-based image slicer to allow for a much cation from proposers before making a !nal smaller spectrograph than that described recommendation to the Gemini Board by by the resolution-slit–width product; it will the end of the month. We expect a selection also have a sensitivity in the wavelength decision to be made at the Board meeting in range between 363-950 nanometers (nm) November. We hope to be able to start the that equals or exceeds that of similar instru- Gen 4#3 !rst design stage in the !rst quarter ments on other world-class facilities. Figure of 2017, although there is some risk in this 9 shows the chart that Andy presented at date, pending the nature of the contract ne- the SPIE conference, which compares the gotiations and approval processes. GHOST predicted performance (dashed red line) against other current instruments in the !eld today. Andy also described the GHOST Progressing Through unique scienti!c role GHOST will have in an Build Phase international context, from exoplanets to The Gemini High-resolution Optical SpecTro- the distant Universe. graph (GHOST) project continues to progress Also presenting at SPIE from the GHOST through the build phase. When completed, project team were Software Project Man-

January 2017 | 2016 Year in Review GeminiFocus 49 ager Peter Young, Software Engineer Jon to conclude at the end of 2017, with com- Nielson, and Project Scientist Mike Ire- missioning at the telescope in 2018. land — all from the Australian National University. Peter and Jon presented a paper and poster on how GHOST will be New Laser Guide Stars Coming controlled with software using the Gem- to Both Gemini Telescopes ini Instrument Application Programmer Gemini o"ers Laser Guide Star (LGS) adap- Interface (GIAPI), the newest Gemini soft- tive optics (AO) at both Gemini telescopes ware framework. Mike’s paper and poster – with Altair in the North, and as an integral showed the precision radial velocity error part of the Gemini Multi-conjugate adaptive budget for the instrument, obtained from optics System (GeMS) at Gemini South. The end-to-end simulations. Although GHOST lasers are projected into the sky where they was not designed for radial excite a small patch of sodium ions in the velocity precision, the 10 me- ionosphere. The re-radiated light from the ters per second requirement sodium layer then forms an arti!cial “guide is feasible; GHOST may also star” (or stars for GeMS) that the AO system achieve a signi!cantly higher uses for wavefront reference. performance than this. Our existing diode-pumped, solid-state la- John Pazder, Project/Opti- sers were state-of-the-art when developed, cal Engineer at Canada’s but that was well over a decade ago; they are National Research Council- now very di$cult and expensive to maintain Herzberg (NRC-H), present- and operate and require signi!cant e"ort — ed a paper and poster cov- from both in-house specialists and external Figures 10-11. ering the optical design of contractors — to keep them calibrated and the bench-mounted spectrograph and the John Pazder and the operational at useful power levels. predicted resolution and e$ciency for the first three optics for the Recently, a new technology has emerged GHOST spectrograph. spectrograph. The following GHOST proj- that presents us with an opportunity to up- Credit: Greg Burley, NRC-H ect team members were also in attendance: grade our lasers. Called Raman !ber laser Project Manager/Detector Engineer Greg ampli!cation, it is in widespread use in !ber Burley, from NRC-H; Optics Engineer Ross optics communication systems. A partner- Zhelem, from AAO; and Instrument Scientist ship between Toptica Photonics in Germany Steve Margheim, Systems Engineer Andrew and MPB Communications in Canada, has Serio, and Project Manager David Hender- applied this technology — licensed from the son, from Gemini. European Southern Observatory (ESO) — in The NRC-H team building the bench-mount- LGS systems that use their SodiumStar laser ed spectrograph subsystem recently re- system; Gemini selected this option after an ceived the !rst major optical components open competition to provide new lasers for from vendors. The !rst three optical blanks Gemini. The SodiumStar system provides a (Figures 10 and 11) came from Schott in Ger- “turn-key” laser, with very low maintenance many and were inspected at NRC-H prior to requirements, and is very simple to operate. being shipped out for further processing: We are planning to put SodiumStar lasers on grinding, polishing, and coating at another both Gemini telescopes, starting at Gemini vendor. These optics make up the spectro- South. The project is well under way with graph’s white pupil relay section. We expect the laser in production at Toptica and Fac- the build phase, the project’s longest phase, tory Acceptance Testing scheduled for late

50 GeminiFocus January 2017 | 2016 Year in Review 2016. We expect to install the laser on the sity, and Macquaire University. The project Gemini South telescope in mid-2017 and will upgrade the near-infrared wide-!eld start on-sky commissioning. Meanwhile, imager and multi-object spectrometer FLA- we’re preparing the telescope for the new MINGOS-2 (F-2) with two medium-band laser’s mounting and cooling systems and !lters designed to split the 1.9-2.5 micron negotiating the contract to purchase a simi- spectral range for sensitive imaging surveys lar laser for Gemini North. The timeline is less of very red objects. certain, but we would expect to have the la- After the start of the project, the team com- ser on-sky sometime in 2018. pleted the design of the !lters and !nished the speci!cations in collaboration with Coming Soon: Gemini Gemini’s F-2 team. A TAMU subcontract is Instrument Upgrade Projects — now making !lters and planning the qual- Request for Proposals ity check tests the team will execute in both the laboratory and the Gemini telescope. Gemini Observatory is planning to invite the The aim is to make this new capability avail- community to participate in the 2016 Re- able to the community in the second quar- quest for Proposals (RfP) for Instrument Up- ter of 2017, enabling a wide range of po- grades. This initiative aims to establish annual tential science from detecting young stellar proposal calls for science-driven upgrades to object candidates in deeply obscured star- Gemini’s facility instruments, including proj- forming regions, to deep K-band imaging ects that may rely upon in-kind contributions to study the demography of high-redshift or telescope time as compensation. This year, massive galaxies. Gemini will provide a total budget of 600,000 USD to fund one or more projects. The avail- able budget was developed to fund one small July 2016 (~100,000 USD) and one medium (~500,000 Figure 12 (left). USD) upgrades, but we are open to the dis- GMOS CCD Update Bias image with the new tribution of funds from 0 to the 600,000 USD The GMOS-N CCD upgrade project encoun- GMOS-N focal plane total available budget. tered some technical delays and is now back array while adjusting the vertical clock voltages to To encourage a wide variety of participant on track for installation later this year. The optimize the full well. organizations in this opportunity, Gemini reason is because the latest Astronomical will provide up to one night (10 hours) of Research Camera (ARC) controllers (which Figure 13 (right). observing time per project to be used on are di"erent from those in GMOS-S) created Sum of 10 acquisitions demonstrating the scienti!c potential of the unexpected technical issues, such as high from GMOS-S to reveal upgraded instrument. The RfP will be re- read-out noise (RON). the very low level pattern. leased by or in October 2016 and will re- main open through the end of the year. Further information and updates can be found here.

In the 2015 RfP, the total budget was 100,000 USD and the award went to Casey Papovich and his team from Texas A&M University and astronomers from the University of Toronto, Swinburne University of Technology, Leiden Univer-

January 2017 | 2016 Year in Review GeminiFocus 51 the CCD’s electrical interface, allowing di- rect and safe measurement of the signals at the CCD pins. This also provided faster testing as we could avoid the thermal cycle overheads. This “dummy CCD board” will be- come a new diagnostic tool for operation at both Gemini North and South.

LGSF Update Gemini South is procuring a new laser from the German corporation Toptica Photonics AG for the Gemini South Multi-conjugate adaptive optics System. On April 28th three representatives of Toptica’s Laser Guide Star Figure 14. Tim Hardy from Canada’s National Research Facility (LGSF) upgrade project, and stake- Participants of the LGSF Council-Herzberg (NRC-H) helped debug holders from science and engineering op- kick-off meeting visit the the GMOS-N detector system, getting its erations, attended the kick-o" meeting for Gemini South telescope performance closer to that of the already- facility in Chile. Toptica’s SodiumStar 20/2, the company’s installed GMOS-S system. We have been able new laser guide star system. to lower the RON from 5.6 electrons-root

mean square (erms) down to 3.9erms (current Participants visited Cerro Pachón where they GMOS-S performances). We also replaced clari!ed several technical issues to ensure the two original cable sets that were found smooth installation of the new laser at the to be erratic, and repaired two new boards Gemini South telescope (Figure 14). Meet- Figure 15 (left). designed to mitigate electrostatic damage ing participants also discussed the delivery Illustration showing to the charge-coupled devices (CCD). By re- schedule and required infrastructure to re- the area on the altitude producing one of the “unwanted features” of ceive the new laser. platform where the EC and the current GMOS-S focal plane array (very LH will be located on the For e$cient operations we will install the low level pattern removable by dithering) we Gemini South telescope. Toptica Laser Control Electronics Cabinet have learned how to work around this issue (EC) and the Laser Head (LH) on the el- in the future (Figures 12-13). Figure 16 (right). evation platform of the telescope, near the Laser Head (left) and We conducted some of these tests using a Lockheed Martin Coherent Technologies la- Electronics Cabinet (right). custom printed circuit board that simulated ser enclosure. This will allow easier injection of the Toptica laser beam into the tele- scope Beam Trans- fer Optics. Figures 15 and 16 show the EC and LH as well as their planned lo- cation on the tele- scope structure.

52 GeminiFocus January 2017 | 2016 Year in Review instrument. The team will run them through Figure 17. a series of tests before they are ready for Prototype cryostat for installation of the CCD detectors, the most GHOST at the NRC-H. costly components in the instrument.

The AAO continues to make progress on the optical cable assembly (see Figure 18). The Figure 18. work to test the performance of the optical The assembled GHOST !bers after the ends were !xed and polished optical fiber array now is complete, yielding excellent results. The assembled in the input next step is to attach the microlens arrays pattern. Seen here are the to the !ber ends. The team will do this after illuminated fiber arrays these arrays receive their optical coating. for the low-resolution object and sky Integral The ANU keeps steadily working on both the Field Units (IFUs) on top, instrument control system software and the and the high-resolution data reduction pipeline. object IFU on bottom.

GHOST on the Move The Gemini High-resolution Optical Spec- Trograph (GHOST) team has started the proj- ect’s build phase. This means that the two organizations building the hardware — the Australian Astronomical Observatory (AAO) and Canada’s National Research Council- April 2016 Herzberg — are busy procuring and fabri- GHOST Update cating components; meanwhile, the Austra- lian National University (ANU) software team We continue to make good progress on the continues to move forward on their work. As Gemini High-resolution Optical SpecTro- components arrive, assemblies will be built graph (GHOST) project. In early March 2016, and tested. Several of these assemblies are we held the second half of a two-part project highlighted here. milestone: the Critical Design Review at Can- ada’s National Research Council-Herzberg in The NRC-H has built a prototype cryostat for Victoria, British Columbia. The review com- the charge-coupled device (CCD) detector mittee was generally quite pleased with the system, shown in Figure 17. The tall cylinder progress made, impressed with the quality of contains the cryocooler, with the vacuum the GHOST team’s design, and satis!ed with valve and vacuum sensor in front of the the improvements made in team coordina- cooler. NRC-H has used this prototype for tion and integration, expressing con!dence various tests to check the system design and in the team’s ability to successfully complete is now fabricating the !nal cryostats for the the instrument.

January 2017 | 2016 Year in Review GeminiFocus 53 This review primarily focused on the spec- enough for regular operations, the process trograph’s opto-mechanical and thermal of !nding a replacement system is now well enclosure designs. It also provided several under way. recommendations for design and process The National Science Foundation, in part- improvements that we are currently imple- nership with AURA/Gemini, has selected menting. Toptica Photonics AG to produce a new laser Another bit of positive news is the arrival of for GeMS. The new laser will still produce the the red and blue CCD detectors, both engi- constellation of !ve arti!cial guide stars on neering and science grade. For both science which GeMS relies to provide excellent and grade CCDs, the vendor test results show stable image quality over the Gemini South excellent quantum e$ciency performance Adaptive Optics Imager’s full !eld-of-view. and a higher grade quality than expected. We expect the new laser will be signi!cantly more robust and reliable than the old one, removing what has been an achilles heel of GeMS Laser Progress GeMS in operation. Users of the Gemini Multi-conjugate adap- tive optics System (GeMS) will know that the GeMS laser has caused signi!cant is- Gen 4#3 sues over the past year, particularly since The Gen 4#3 team has made steady prog- the earthquake of September 2015. Major ress in the past three months on crafting e"orts !nally got us back to a working sys- the Request for Proposals (RfP) for this next tem (delivering 30 of its 50 watts, which is facility instrument. In their November 2015 su$cient in good conditions) by the time meeting, the Gemini Board requested the of the February 2016 GeMS run. However, Science and Technology Advisory Com- as the current laser (Figure 19) is not robust mittee (STAC) review the outcomes of the Gemini Instrument Feasibility Studies and Figure 19. work with Gemini to identify core capabili- The Gemini South ties. The Board also placed a high priority laser propagating prior to the on schedule and cost control. The STAC met September 2015 in December and identi!ed some expand- earthquake. ed core capabilities for the Gen 4#3 instru- ment. They also highlighted the importance of instrument throughput and operational e$ciency. They agreed that schedule is a primary driver for Gen 4#3, and empha- sized that Gemini should be fully prepared to use Gen 4#3 to take advantage of early Large Synoptic Survey Telescope (LSST) sci- ence. We are therefore driving the Gen 4#3 schedule to help ensure the instrument is commissioned by the planned start of LSST science operations.

54 GeminiFocus January 2017 | 2016 Year in Review Inger Jørgensen

A Transition Comes to an End

Gemini’s Transition Program 2011-2015

In 2010 the United Kingdom announced its intention to leave the Gemini Partnership. This prompted the Observatory to plan for a roughly 25% reduction in its annual operations Figure 1. budget, which translates to about $6.5 million in 2012 dollars. To handle this situation, we Savings from the developed a plan that touched all areas of the Observatory, including nighttime science Transition Program operations, energy consumption, maintenance schedules for printers, and just about every- projects. Amounts are in thing in between. Thanks to the Observatory’s available cash reserves, we could stretch the thousands of dollars. implementation through 2015.

The plan, called the Transition Program, con- sisted of three general areas of focus: sta" re- ductions, general reductions, and the imple- mentation of speci!c projects. Sta" reductions contributed about $3.5 million to the required savings. General reductions in non-labor ex- penses — enabled by tight tracking of budgets, reduction in travel expenses, lower computer prices, etc. — saved about $1.5 million. And the implementation of about 25 projects (aimed at reducing non-labor costs or enabling opera- tions with a smaller sta") also secured about $1.5 million, of which about $400,000 are still to be realized in 2016. Figure 1 gives an overview of these savings.

Some of the changes resulting from the Transi- tion Program are visible to our users while many are only visible internally. As of this writing, the

January 2017 | 2016 Year in Review GeminiFocus 55 Observatory has implemented the majority Changes that A"ect Our Users of the Transition Program. Ongoing devel- Users are most directly a"ected by changes opments continue in 2016 on projects that within Science Operations. Table 1 summa- enable additional energy savings, reduce rizes these changes as well as those within expenses (such as restructuring lab space Engineering Operations, which indirectly at Gemini South for use as o$ce space), and impact our users. support for the transition to Base Facility Op- erations at Gemini South.

Table 1. Changes affecting our users. Change Description Reduced (and In early 2013 we changed the quality assessment on queue data to be done primarily changed) data quality at night by the observer. Only Band 1 data receive additional checks during the day. In assessment addition, we have implemented an automatic data quality assessment pipeline, which covers all imaging and acquisition observations. Users are encouraged to review their data promptly and contact us in case of issues. The fraction of observations that have to be repeated has not increased due to these changes. Non-research queue We have gradually phased in non-research sta$ members as queue observers. The goal is observers for non-research sta$ to perform 75% of the queue observing. This has been the case at Gemini North for several semesters and we expect that Gemini South will reach a similar level within 1-2 semesters, as training is completed. Base Facility We have moved nighttime operations to the Gemini North Base Facility. The same will Operations take place at Gemini South in 2016. Visiting observers are (positively) a$ected by this change, which also saves a total of about $400,000 annually in lodging, meals, and transportation costs. Archive We have implemented an archive that serves all science (and engineering) data from the Amazon Web Services. The archive went through extensive reviews by the Users Committee, sta$ from the National Gemini O(ces, and repeat users of Gemini. Full implementation was in place by December 2015, and the move saves us more than $200,000 annually. The archive is available here: https://archive.gemini.edu Priority Visitors Principal Investigators of Large and Long programs and selected Band 1 programs can now visit Gemini as Priority Visitors. They can take their own data (if conditions allow) or execute queue observations. This arrangement improves our contact with users, while saving a small amount of sta$ e$ort. Four facility The two Gemini telescopes will each operate with a maximum of four facility instruments instruments + and a facility adaptive optics system. This ensures that we (with the reduced sta$) have adaptive optics at su(cient e$ort to support these instruments. each site Reductions in A reduction in engineering sta$, coupled with the above-mentioned limitation on facility engineering sta! instruments, means that we will not be able to support future major instrument rework or instrument building (such as on FLAMINGOS-2 and Canopus). Thus, any instruments procured in the future will have to meet requirements prior to arriving at Gemini. The reduced engineering sta$ may also mean that major technical faults have a longer response time.

56 GeminiFocus January 2017 | 2016 Year in Review Behind the Scenes The End Result Our users will not see many of the essential With the Gemini Transition Program chang- Transition Program changes required for re- es largely executed, the Observatory is now alizing savings on the non-labor budget, as in a healthy state to move forward in a more well as those enabling us to operate with a streamlined, e$cient, cost-e"ective, and reduced sta". Table 2 presents a brief over- energy-conscious way. The Observatory is view of the most important of these chang- thankful for the universal cooperation it re- es. Figure 1 shows the non-labor savings ceived during this di$cult period. Gemini from some of them. is now better positioned to focus on the

Table 2. Changes “behind the scenes.” Change Description Software supporting We have developed software that decreases the e$ort needed to operate the queue. queue operations The software covers queue !lling during the Time Allocation Committee process, queue planning through visualization tools, and handling of the military’s requirement for clearances during laser operations. Software leading to The Observatory Control System software has been upgraded and improved, primarily lower maintenance to lower the maintenance e$ort. However, improvements in both the Phase I Tool and e!ort the Observing Tool have greatly bene!ted our users. Energy Energy saving projects are a core component of the Transition Program. We have installed photovoltaic panels at the telescope on Maunakea (Figure 2); in 2016 we plan to do the same at the Base Facility in Hilo and on Cerro Pachón. We are also applying the recommendations from an energy audit of the Gemini North facilities, which include replacing the chillers at the summit, refurbishing the air conditioners at the base, and replacing all lighting with LEDs. All computer rooms have been separated into hot/cold zones. The total annual savings on our electricity costs are $400,000, while we reduce by about 30% our reliance on utility-provided power (most of which is produced using fossil fuels). Base Facility space We have reduced the need for external storage at Gemini North, while at Gemini South usage lab space will be converted to o(ce space; these changes will remove the need for renting additional buildings for o(ces. Spares After reviewing our spares inventory and purchases and making better risk assessments, we have signi!cantly reduced the funds used annually to restock spares. Overtime We reduced overtime payments to hourly paid sta$, primarily by eliminating weekend checks at Gemini South and limiting overtime usage during telescope shutdowns.

Software licenses Sizable savings were realized by switching either to software with lower license costs or to free software. Administrative services Purchasing, contracts, and human resources administration are centrally handled by AURA, either in Tucson or by personnel in La Serena. Transportation We have eliminated several vehicles at both sites, and restructured the use of common transportation at Gemini South.

January 2017 | 2016 Year in Review GeminiFocus 57 needs of its global Partnership, the future of its scienti!c programming, and the suite of leading-edge instruments that will take us to the forefront of research while remaining !scally responsible.

Inger Jørgensen is Gemini‘s Deputy Associate Director of Operations. She can be reached at: [email protected]

Figure 2. Recently installed photovoltaic panels on the Gemini North telescope facility on Maunakea are some of the energy saving initiatives that are part of the Transition Program. Since installation, the panels have provided approximately 10% of the energy needed at the Gemini North telescope. Image credit: Joy Pollard

58 GeminiFocus January 2017 | 2016 Year in Review Alexis-Ann Acohido

Figures 1-2. Photovoltaic panel installations at the Gemini South Cerro Gemini Harnesses the Sun Pachón facility in Chile (top and bottom). from Both Hemispheres

In 2015 the Observatory installed photovoltaic (PV) panels on the Gem- ini North Maunakea facility. Now we have done the same on the Gemini South Cerro Pachón facility and the Gemini North Hilo Base Facility. The e"ort is part of our commitment to positive stewardship of our planet and eco-e$cient operations.

Installation of an impressive 680 pan- els at the Gemini South Cerro Pachón facility was completed in late June, 2016, and the cabling phase to con- nect them to Gemini’s electrical sys- tem should be completed by the release of this issue of GeminiFocus. The panels are on the rooftop adja- cent to the telescope dome, as well as mounted on the ground (Figures 1 and 2), and are estimated to provide ~20% of the annual power consump- tion at the telescope.

January 2017 | 2016 Year in Review GeminiFocus 59 Almost simultaneously, panel installation on Alexis Ann Acohido is a Media Relations and Lo- the roof of HBF (Figures 3 and 4) started in cal Outreach Assistant at Gemini North. She can late May 2016 and ended in mid-June 2016. be reached at: [email protected] Cabling of the system was completed on June 15, 2016, and the panels are now online.

Figures 3-4 Installation of photovoltaic panels on rooftop of Gemini’s Hilo Base Facility in Hawai‘i (top and bottom).

60 GeminiFocus January 2017 | 2016 Year in Review Peter Michaud

Gemini Connections

Authors of three recent books on astronomy share direct ties with Gemini. The books cover topics spanning the history of modern astronomy on Maunakea, how astronomers create stunning astronomical images, and the story of George Herbig’s pioneering work in early stellar evolution. Brief reviews of these works follow. Figure 1. A Sky Wonderful with Stars: Image from the 50 Years of Modern Astronomy on Maunakea Michael West book “A Sky Wonderful This absolutely stunning book by Michael J. West is clearly a labor of love fueled by a pas- with Stars: 50 Years of sion for astronomy. Some will recall that Michael served as Gemini’s Head of Science Op- Modern Astronomy on erations at Gemini South from 2006-2007, as well as a professor of astronomy and physics Maunakea.” at the University of Hawai‘i Hilo, and his in#uence re- mains strong especially on Maunakea. Michael is cur- rently the Deputy Director of Science at the Lowell Ob- servatory in Arizona.

Michael’s love for astron- omy and Maunakea is evi- dent on every page of this book. Thanks to the vision of the University of Hawai‘i Press this book was made possible in 2015 to coincide with the 50th anniversary of the !rst telescopic observa- tions of the Universe from Hawaii’s highest peak.

January 2017 | 2016 Year in Review GeminiFocus 61 With each page readers experience a pro- to a level of artistry that is evident with even found view, and written perspective, of the a quick #ip-through of this 250-page large- mountain and the Universe (Figure 1). Mi- format book. chael tells the story of modern astronomy The authors use accessible language and on Maunakea with an elegance that borders striking astronomical images to describe and on poetry; his words transcend the printed show the telescopes and instruments used page and succeed in conveying the poetry of to take these colorful images (Figure 2), the Figure 2. the mountain and modern astronomy. This techniques of astronomical data processing, Excerpt from the book large-format book belongs on the co"ee ta- and what astronomy we can learn from the “Coloring the Universe” ble of everyone who loves the unparalleled that features dozens of results. The chapters are merged seamlessly beauty of both Maunakea and astronomy. Gemini images. into a cohesive story in this book published by the University of Alaska Press, Fairbanks (where Rector teaches astronomy and physics).

George Herbig and Early Stellar Evolution A new Gemini Board mem- ber, Bo Reipurth, from the University of Hawaii’s Insti- tute for Astronomy, is au- thor of a recently published book that chronicles the life and work of astronomer Coloring the Universe: George Herbig (Figure 3). All astronomers (and most Astronomy 101 students) know An Insider’s Look at Making something about George and his work on Spectacular Images of Space the early evolution of stars. However, did Anyone familiar with Gemini’s Legacy Im- you know that although his mother encour- ages will recognize Travis Rector’s name as aged him to become a chemist (it paid well), the creative genius who massages selected his passion for astronomy and amateur tele- Gemini data into aesthetically pleasing pic- scope making kept him !rmly entrenched on tures. While his work isn’t limited to Gemini his ultimate career path (which is fortunate data (he has worked for years with Cerro To- for astronomy). lolo Inter-American Observatory, Kitt Peak Bo is in a unique position to write this biog- National Observatory, and other observa- raphy, since George — prior to his death at tories) his experience makes him uniquely age 93 and while still in his mid-70’s — en- quali!ed to serve as an “insider” as the book’s trusted to Bo volumes of his detailed notes, subtitle states. Joining Travis in this ambi- comments, and autobiographical sketches. tious work are NASA’s Kimberly Arcand and In the book’s foreword, Bo includes this Megan Watzke, who collectively have pro- quote from George, as he documented his duced and promoted astronomical imaging life as a scientist:

62 GeminiFocus January 2017 | 2016 Year in Review “For reasons not entirely clear, I have Astronomy owes a huge debt to George’s thought it worthwhile to try to put down “frittering,” as does Bo for telling the en- a kind of inventory or outline of the vari- gaging story of this remarkable man. Bo ous astronomical activities that I have pur- has generously made this self-published sued, and how my involvement in each of e-book freely available for download here. them came about — to the extent that I can remember or reconstruct reasons and motives at this late date (January 1993). Peter Michaud is the Public Information Out- reach Manager of Gemini Observatory. He can The scornful phrase ‘jack of all trades, mas- Figure 3. be reached at: [email protected] ter of none’ has more than once come to Extracted pages from my mind, for I recall old-timers speaking Bo Reipurth’s book on with contempt of colleagues who frittered George Herbig. away their energies on a host of activities rather than spending their lives bearing down on a single area... .”

January 2017 | 2016 Year in Review GeminiFocus 63 Gemini Legacy Image Releases A New Look for Gemini’s Legacy Images

A beautiful new set of 16 Gemini Leg- acy images, in English and Spanish, are now available in redesigned 8.5 x 11-inch prints (or as electronic !les). Shown here are several examples of the new sheets (including back- ground information which is pro- vided on the #ip-side of each sheet).

All of these, plus prior Legacy im- ages not included in this update, are available as full-resolution down- loads on the Gemini Image Gallery. Gemini’s participating country of- !ces (and the public) may request printed copies via email.

We hope you enjoy these images, and watch for spectacular new ones as Gemini continues to ex- plore the Universe!

64 GeminiFocus January 2017 | 2016 Year in Review January 2017 | 2016 Year in Review GeminiFocus 65 Observatory Careers: New Resources for Students, Teachers, and Parents Gemini !rst developed resources for promoting observatory career opportunities primarily for use in our local host community outreach. We’ve now made updated (and expanded) versions which are available to anyone online — and in printed form upon request.

Chances are, at one time or another, you’ve met a young student who loves astronomy and wants to know more about astronomy and observa- tory careers. Like any career advice, there is no simple answer for every- one, so Gemini is here to help! The latest update (Version 2.0) of Gemini’s Career Brochure and companion website is now available. Here you will !nd a selec- tion of highlighted observatory careers, from research astronomers to administra- tive support. To augment the brochure, we now o"er in-depth pro!les of selected sta", with more on the way. The website also o"ers online video interviews of sta" from a wide variety of occupations. On- line materials are available in both Eng- lish and Spanish at this site; and printed Gemini Career Brochures versions are available by sending a re- are available in both quest via email to: English, and Spanish. English and Spanish.

66 GeminiFocus January 2017 | 2016 Year in Review We hope you !nd these resources helpful, and we look forward to your input so we can make the next versions even better!

January 2017 | 2016 Year in Review GeminiFocus 67 Alexis-Ann Acohido

Figure 1. Hilo High students observe various light sources through gratings that create a spectrum and separate the light into a Journey Through the Universe: rainbow of colors. Figure 2. Gemini Safety Manager John Vierra engages Twelve Years, and Counting! students with safety equipment that observatory Each year, for the past 12 years, Journey Through the Universe, technicians must wear to work on large telescopes. Gemini North’s premiere local educational outreach program, has impacted thousands of Hawai‘i Island students. The program is designed to increase their interest in Science, Technology, Engineering, and Math, while inspiring them to participate in the exploration of the Universe.

Early in March 2016, over 80 observatory sta" pro- fessionals — ranging from astronomers to infor- mation technology specialists — shared their pas- sion for exploration with over 7,000 local Hawai‘i students. The excitement and energy can be seen here in the selection of images from the 12th an- nual Journey Through the Universe program on the Big Island of Hawai‘i, a week-long event that be- gan on March 4th.

The program is a collaboration with the Depart- ment of Education Hilo-Waiākea Complex, Hawai‘i Island business community, Maunakea observa- tories, and NASA. More images and details can be found on the program’s webpage.

68 GeminiFocus January 2017 | 2016 Year in Review Figure 3 (top, left). Evan Sinukoff (University of Hawai‘i Institute for Astronomy) and Virginia Aragon-Barnes (Thirty Meter Telescope; both at left) direct students on how to “pace” the Universe, using their steps as measurements. Figure 4 (top, right). Subaru Astronomer Julien Lozi (left) and Gemini Public Information and Outreach staff person Alyssa Grace (second from left), make scaled-down comets for students at Waiākeawaena Elementary School using dry ice, gravel, colored sand, and corn syrup. Figure 5 (center, left). NASA Solar System Exploration Research Virtual Institute director Yvonne Pendleton uses coin faces to help students visualize how the Moon rotates as it orbits the Earth and keeps the same side facing the Earth. Figure 6 (center, right). Gemini Science Fellow Jenny Shih (standing) helps students at Waiākea Intermediate School classify galaxies. Figure 7 (bottom, left). Gemini Software Engineer Angelic Ebbers inspires students at Waiākea Elementary to show off their engineering skills in a “Zip Line Challenge.”

January 2017 | 2016 Year in Review GeminiFocus 69 Figure 8 (top left). Hawai‘i Governor David Ige and Hawai’i Lieutenant Governor Shan S. Tsutsui proclaimed March 4-11, 2016, as Journey Through the Universe Week. Figure 9 (top right). Robert Sparks of the National Optical Astronomy Observatory has students at Waiākea High School use filters to observe how light is polarized. Figure 10 (bottom right). Gemini Astronomer Rachel Mason works with students from Hilo’s Connections school to model the relative distances to the planets with toilet paper.

Figure 11 (bottom left). Information Systems Engineer Jerry Brower features a simple representation of the Saturn Gemini Legacy Image, where the pixels are enlarged to illustrate how pictures are stored in computers for students at Waiākea Intermediate.

70 GeminiFocus January 2017 | 2016 Year in Review Manuel Paredes Viaje al Universo 2016: Empowering Students with Science Gemini South’s premiere annual public outreach event extends its programming to expand its impact on our local host community in Chile.

In late October 2016, Gemini South began its sixth annual Viaje al Universo in La Serena, Figure 1. Chile. As in previous years the annual event — which is one of the Observatory’s core public People of all ages attend outreach e"orts — brought more than 20 scientists and professionals from di"erent obser- Viaje’s opening talk vatories into the classroom to motivate students into pursuing future careers in science, by Gemini’s Science technology, engineering, and math (STEM). Operations Specialist Erich Wenderoth. Unlike any other Viaje, which generally lasts one week, Gemini South extended the 2016 Image credit: All images event to o"er more public talks, Starlab presentations, school lectures, family astro-events, by Manuel Paredes

January 2017 | 2016 Year in Review GeminiFocus 71 Figure 2. Gemini South Senior Electronic Technician Pedro Ojeda explains the function and features of astronomical telescopes to students at the Colegio San Nicolás, in La Serena.

Figure 3. Gemini South Public Information Office team member Dalma Valenzuela leads one of the Family Astro activities at the San Martin de Porres school, in Las Compañías, La Serena.

and tours to the Gemini South telescope more than 120 people of all ages attended and its La Serena Base Facility. The idea was this event, held at the Intendencia, the gov- to give students, teachers, and parents more ernment house of the Region de Coquimbo time than ever to attend these special activi- in La Serena. At the end of the lecture, Wen- ties, which are designed to help develop a deroth voiced his opinion on the importance long-term interest in astronomy. of a prolonged Viaje event: “Extending Viaje al Universo beyond the classic week of activi- Gemini’s Science Operations Specialist Erich ties is a huge opportunity to reach a more di- Wenderoth kicked o" Viaje al Universo 2016 verse public interested in the development with a public talk titled, “A Walk through the of science in Chile.” Universe,” which took the audience from the Solar System and beyond — from nebulae During the week of October 24-28, over and clusters in our own Galaxy to other gal- 1,300 students were directly impacted with axies that reached the edge of the observ- a variety of activities in di"erent schools able Universe. A near-capacity audience of throughout La Serena. Over 30 classrooms

72 GeminiFocus January 2017 | 2016 Year in Review Figure 4. Gemini Observatory, Cerro Tololo Inter- American Observatory, and Las Campañas Observatory professionals made up the Career Panel speakers. The feature continues as one of the most popular activities in the annual Viaje al Universo programming.

were visited by 21 professionals from many Chilean observatories, including 14 Gemini Sta".

These presentations covered a wide- range of topics from technical work (such as engineering and instrument design) to scienti!c research — includ- ing breakthroughs based on observa- tions from Chile.

Fernanda Urrutia, an outreach astron- omer at Gemini South who o"ered a presentation during Viaje, said, “I was delighted with the talk I o"ered about the Solar System at the public school San Martin de Porres, as I got very positive feedback from the 10-year- old students. I realized that they came away students. In addition, the little ones had a Figure 5. with an understanding of basic concepts lot of fun drawing constellations with stars Information Systems that they didn’t know before my presenta- sprinkled on cookies that they happily ate Engineer Eduardo tion. That is something encouraging!” later!” For more information about Viaje al Toro chatting with Universo activities please visit this site. students after the panel The Viaje program ended with its popular event about careers in Career Panel, featuring helpful insights on astronomy. how students can pursue a career in astron- omy or a related STEM !eld. Norma Isla, a Manuel Paredes is the Communications Coor- professor at Christ School in La Serena, com- dinator at Gemini South. He can be reached at: mented, “...the opportunity to share with [email protected] top-level scientists is a huge boost for my

January 2017 | 2016 Year in Review GeminiFocus 73 Re"ection Nebula GGD 27 Revealing the Chaotic and Messy Environment of a Stellar Nursery This near-infrared image was obtained using FLAMINGOS-2, the infrared imager and spectrograph on the Gemini South telescope in Chile. It is a

color composite made using four filters: Y (blue), J (cyan), H (green), and Ks (red). The total integration (exposure time) for all filters is just over one hour. The image is 4.6 x 3.5 arcminutes in size and is rotated 35 degrees clockwise from north up and east left. More information can be found here.

The Gemini Observatory is operated by the Association of Universities Canada Brazil Argentina for Research in Astronomy, Inc., under a cooperative agreement with the United States Chile National Science Foundation on behalf of the Gemini Partnership.

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