The Messenger No. 182 | 2021 - European Southern Observatory
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Instrumentation for ESO’s Extremely Large Telescope
SUPER — AGN Feedback at Cosmic Noon
Mapping Stars in the Tarantula Nebula with MUSE-NFM The Messenger
No. 182 | 2021
ESO, the European Southern Observa- Contents
tory, is the foremost intergovernmental
astronomy organisation in Europe. It is ELT Instrumentation
supported by 16 Member States: Austria, Ramsay S. et al. – Instrumentation for ESO’s Extremely Large Telescope 3
Belgium, the Czech Republic, Denmark, Thatte N. et al. – HARMONI: the ELT’s First-Light Near-infrared
France, Finland, Germany, Ireland, Italy, and Visible Integral Field Spectrograph 7
the Netherlands, Poland, Portugal, Spain, Ciliegi P. et al. – MAORY: A Multi-conjugate Adaptive Optics RelaY for ELT 13
Sweden, Switzerland and the United Davies R. et al. – MICADO: The Multi-Adaptive Optics Camera for
Kingdom, along with the host country of Deep Observations 17
Chile and with Australia as a Strategic Brandl B. et al. – METIS: The Mid-infrared ELT Imager and Spectrograph 22
Partner. ESO’s programme is focused Marconi A. et al. – HIRES, the High-resolution Spectrograph for the ELT 27
on the design, construction and opera- Hammer F. et al. – MOSAIC on the ELT: High-multiplex Spectroscopy to Unravel
tion of powerful ground-based observing the Physics of Stars and Galaxies from the Dark Ages to the Present Day 33
facilities. ESO operates three observato- Kasper M. et al. – PCS — A Roadmap for Exoearth Imaging with the ELT 38
ries in Chile: at La Silla, at P
aranal, site of
the Very Large Telescope, and at Llano Astronomical Science
de Chajnantor. ESO is the European Mainieri V. et al. – SUPER — AGN Feedback at Cosmic Noon:
partner in the Atacama Large Millimeter/ a Multi-phase and Multi-scale Challenge 45
submillimeter Array (ALMA). Currently Castro N. et al. – Mapping the Youngest and Most Massive Stars in the
ESO is engaged in the construction of the Tarantula Nebula with MUSE-NFM 50
Extremely Large Telescope.
Astronomical News
The Messenger is published, in hardcopy Berg T. A. M., Ribas Á. – Fellows at ESO 55
and electronic form, four times a year. Zerbi F. M., Fontana A. – In memoriam Nichi D’Amico 57
ESO produces and distributes a wide Lyubenova M. – Message from the Editor 58
variety of media connected to its activi- Personnel Movements 60
ties. For further information, including
postal subscription to The Messenger, Annual Index 2020 (Nos. 179–181) 61
contact the ESO Department of Commu-
nication at:
ESO Headquarters
Karl-Schwarzschild-Straße 2
85748 Garching bei München, Germany
Phone +498932006-0
information@eso.org
The Messenger
Editors: Mariya Lyubenova,
Gaitee A. J. Hussain
Editorial assistant: Isolde Kreutle
Copy-editing: Peter Grimley
Layout, Typesetting, Graphics:
Lorenzo Benassi
Graphics: Mafalda Martins
Design, Production: Jutta Boxheimer
w ww.eso.org/messenger/
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Unless otherwise indicated, all images in
The Messenger are courtesy of ESO,
except authored contributions which are
courtesy of the respective authors.
Front cover: Artist rendering of the instruments HARMONI,
MICADO, MAORY and METIS, together with the prefocal station A,
© ESO 2021 sitting on one of the Nasmyth platforms of ESO’s Extremely Large
ISSN 0722-6691 Telescope.
2 The Messenger 182 | 2021
ELT Instrumentation DOI: 10.18727/0722-6691/5214
Instrumentation for ESO’s Extremely Large Telescope
Suzanne Ramsay 1 The Messenger 140, 2010). While ESO is approval of the next design phases and
Michele Cirasuolo 1 ultimately responsible for delivering the the construction of the LTAO module was
Paola Amico 1 instruments to the scientific community on signed in 2019 when funds for this module
Nagaraja Naidu Bezawada 1 time and with the expected performance, became available. It will now be delivered
Patrick Caillier 1 an important feature of the Instrumentation along with HARMONI for first light with the
Frédéric Derie 1 Plan is that the instruments are being spectrograph, ensuring optimised perfor-
Reinhold Dorn 1 developed in collaboration between ESO mance and increased sky coverage.
Sebastian Egner 1 and consortia made up of universities
Elizabeth George 1 and institutes in the Member States and The instruments under construction have
Frédéric Gonté 1 beyond. This model has worked very now completed the important preliminary
Peter Hammersley 1 successfully for the delivery of instru- design phase, during which the basic
Christoph Haupt 1 ments to the Very Large Telescope (VLT) concept for the instrument is refined and
Derek Ives 1 and is a key aspect of the interaction compliance with the scientific and techni-
Gerd Jakob 1 between ESO as an organisation and the cal requirements is confirmed. The first
Florian Kerber 1 astronomical community. Figure 1 shows Preliminary Design Review (PDR) meet-
Vincenzo Mainieri 1 a timeline for instrument development as ing, for HARMONI, was held in November
Antonio Manescau 1 it stands at the time of writing. 2017, those for MICADO and METIS
Sylvain Oberti 1 followed in October 2018 and May 2019,
Celine Peroux 1 A pair of instruments was selected by respectively. Everything about these pro-
Oliver Pfuhl 1 the ELT Science Working Group to be jects is on a very large scale, as befits the
Ulf Seemann 1 delivered for first light: the High Angular extreme size of the telescope. The effort
Ralf Siebenmorgen 1 Resolution Monolithic Optical and Near- that goes into the PDRs is no exception.
Christian Schmid 1 infrared Integral field spectrograph The document package for each instru-
Joël Vernet 1 (HARMONI) and the Multi-adaptive optics ment amounts to more than one hundred
and the ESO ELT Programme Imaging CamerA for Deep Observations documents and many thousands of
and follow-up team (MICADO), a near-infrared camera. Adap- pages. The design concepts have been
tive optics systems tailored to meet the reviewed by tens of engineers from ESO
scientific goals of each of these instru- with support from external experts from
1
ESO ments are also being developed. The industry and from other extremely large
HARMONI Consortium is building a laser telescope projects, such as the Thirty
tomographic adaptive optics (LTAO) mod- Meter Telescope (TMT)2 and the Giant
Design and construction of the instru- ule. A multi-conjugate adaptive optics Magellan Telescope (GMT)3. Each of
ments for ESO’s Extremely Large Tele- (MCAO) module, the Multi-conjugate these instruments is now formally in the
scope (ELT) began in 2015. We present Adaptive Optics RelaY (MAORY), is being final design phase during which the
here a brief overview of the status of developed as a facility adaptive optics design is detailed to the level that manu-
the ELT Instrumentation Plan. Dedi- system with two “clients” — MICADO facturing of the key components can start
cated articles on each instrument are and a future multi-object spectrograph. after the Final Design Review (FDR) is
presented elsewhere in this volume. Together this first light pair of workhorse concluded. The design for MAORY has
instruments will immediately exploit both undergone significant revision since the
the enormous collecting area and the Phase A study; it has been optimised for
Instruments planned for ESO’s ELT superb spatial resolution of the new tele- manufacturability and ease of alignment,
scope, enabling a wide range of scientific compliance with the available volume and
When, in December 2014, the ESO projects to be executed at first light. The mass, and also to ensure that it provides
Council gave the green light for the con- next instrument in the Instrumentation a good interface for the two client instru-
struction of the 39-m Extremely Large Plan is the Mid-infrared ELT Imager and ments. The PDR for MAORY is planned
Telescope1 in two phases (de Zeeuw, Spectrograph (METIS), working in the for the second quarter of 2021.
Tamai & Liske, 2014), this triggered the mid-infrared (3–14 µm) with single-
final preparations to launch the design conjugate adaptive optics (SCAO). All of As the instrument designs have pro-
and construction of the powerful instru- these instruments are formally part of gressed, much has been learnt about the
ment suite for this telescope. The ELT ESO’s ELT Construction Programme. real resource requirements of these huge
Instrumentation Plan, to provide the Agreements for the design, construction systems with their challenging perfor-
instruments to meet the science case for and commissioning of the three instru- mance specifications. Mass and power
the telescope, had already been defined ments plus MAORY were signed in 2015. budgets, space envelopes, vibration con-
in consultation with ESO’s science com- The LTAO module for HARMONI was one trol and maintenance requirements are
munity and scientific and technical advi- of the Phase 2 items whose funding was major topics of discussion. Careful follow-
sory committees. The instruments were initially deferred (de Zeeuw, Tamai & up and management of these items has
selected following a set of Phase A Liske, 2014) and so only the work to carry allowed MICADO, HARMONI and METIS
conceptual design studies that have been out the preliminary design was included to move into their FDR phases without
described previously (see papers in in the agreement for HARMONI. Formal any loss of functionality or performance,
The Messenger 182 | 2021 3
ELT Instrumentation Ramsay S. et al., Instrumentation for ESO’s Extremely Large Telescope
Figure 1. The ELT
Instrument Main specifications Schedule Instrumentation
Field of view/slit length/ Spectral Wavelength
roadmap and timeline.
Phase A Project PDR FDR First
pixel scale resolution coverage (µm) start light
Imager (with coronagraph) I, Z, Y, J, H, K +
50.5ಿ × 50.5ಿ at 4 mas/pix narrowbands
MICADO 19ಿ × 19ಿ at 1.5 mas/pix 0.8–2.45 2010 2015 2019
Single slit R ~ 20 000
AO Module
MAORY 0.8–2.45 2010 2015
SCAO – MCAO
IFU 4 spaxel scales from:
R ~ 3200
HARMONI + 0.8ೀ × 0.6ೀ at 4 mas/pix to
R ~ 7100 0.47–2.45 2010 2015 2018
LTAO 6.1ೀ × 9.1ೀ at 30 × 60 mas/pix
R ~ 17 000
(with coronagraph)
Imager (with coronagraph)
L, M, N +
10.5ೀ × 10.5ೀ at 5 mas/pix in L, M
narrowbands
13.5ೀ × 13.5ೀ at 7 mas/pix in N
R ~ 1400 in L
METIS Single slit R ~ 1900 in M 3–13 2010 2015 2019
R ~ 400 in N
IFU 0.6ೀ × 0.9ೀ at 8 mas/pix L, M bands
(with coronagraph) R ~100 000
Single object
R ~100 000
HIRES IFU (SCAO) 0.4–1.8 simultaneously 2018
Multi object (TBC) R ~10 000
~ 7-arcminute FoV R ~ 5000–20 000 0.45–1.8 (TBC)
MOSAIC ~ 200 objects (TBC) 2018
~ 8 IFUs (TBC) R ~ 5000–20 000 0.8–1.8 (TBC)
Extreme AO camera and
PCS TBC TBC
spectrograph
1 milliarcsecond (mas) = 0.001ೀ
despite some greatly increased demands first-light instruments. These instrument observing parameter space, allowing
on the telescope and the observatory. studies concluded in 2018. astronomers to tackle a very broad range
MAORY is also on track to meet its of science cases that will fully exploit the
requirements as the PDR approaches. The next stage of construction of collecting power and diffraction limit
The lessons learnt from these pioneering HIRES and MOSAIC, and the funding of the ELT. As shown in Figure 2, users
instruments are being applied to the of the future ELT Planetary Camera and will have access to imaging and spec-
development of future instruments. Spectrograph (ELT-PCS), fall outside troscopy, across a wide range of wave-
the ELT Construction Programme and lengths and spectral resolving powers, in
In addition to the first three instruments within the Armazones Instrumentation a variety of observing modes, and includ-
and their adaptive optics modules, the Programme (AIP). The AIP will manage all ing high-contrast, precision astrometry
ELT Construction Programme included future instrument development during the and non-sidereal tracking.
two Phase A studies, for a multi-object lifetime of the ELT. The agreements for
spectrograph (named MOSAIC), and the construction phase of MOSAIC and ELT-PCS is the planet hunter that will
a high spectral resolving power, high- HIRES, including the detailed scientific deliver one of the highest priority and
stability spectrograph (named HIRES). requirements, are being finalised now. most challenging science goals of the tel-
The original Phase A design studies car- ESO’s committees support the start of escope — the detection and characteri-
ried out from 2007 to 2010 included three the construction of these instruments sation of exo-Earths. Given the rapidly
separate concepts for a multi-object spec- once the resources (funding, effort and changing understanding of the popula-
trograph (OPTIMOS-EVE, Hammer, Kaper Guaranteed Time) needed to complete tion of exoplanets and the many new
& Dalton, 2010; OPTIMOS-DIORAMAS, the first instruments are well understood facilities that are being developed to
Le Fèvre et al., 2010; and EAGLE, Morris and secured. This milestone is expected study them, it was decided in 2010 that
& Cuby, 2010) and two for a high resolv- when the last of the PDRs for the first ELT-PCS should start later in the overall
ing power spectrograph (CODEX, instruments is complete. An important timeline in order to allow for develop-
Pasquini et al., 2010 and SIMPLE, Origlia, step towards the launch of the MOSAIC ments in the science case. Furthermore,
Oliva & Maiolino, 2010). In 2016 ESO and HIRES construction phases was the achieving the extreme contrast ratios
issued a call for two Phase A studies for recent approval by the ESO Council for required for these observations requires
HIRES and MOSAIC in order to update the procurement of the second prefocal research and development in the field of
and optimise the scientific scope and station for the Nasmyth B platform that adaptive optics and coronagraphy. Proto-
specifications of these instruments, tak- will host MOSAIC and HIRES. Taken typing of components that are needed
ing into account how best to complement together, the instruments so far planned for ELT-PCS is part of ESO’s ongoing
the observing capabilities offered by the for the ELT offer excellent coverage of the Technology Development programme.
4 The Messenger 182 | 2021
The development of this instrument is HARMONI will use the Teledyne-e2V being carried out under the Technology
linked to both the level of technical readi- CCD231-84 deep-depletion silicon Development Programme.
ness of these prototypes and the availa- CCDs already used in the Multi Unit
bility of funding and effort. Spectroscopic Explorer (MUSE). Both Expertise in adaptive optics is also an
MICADO and HARMONI will use the important input to the instrument consor-
In other articles in this issue details of Hawaii 4RG detector from Teledyne-e2V tia. In this regard, ESO engineers and
the science case, operational modes and for their near-infrared modules. METIS physicists work within the instrument con-
instrument concepts are given for each will use near-infrared detectors from the sortia, fully integrated into the teams, pro-
of the instruments. Hawaii “family”, the Hawaii 2RG, for its viding backup for simulating the telescope
LM-band imager and spectrometer. behaviour and instrument performance,
A particularly exciting development for developing the calibration strategies for
Activities at ESO METIS is that it will use a new detector the adaptive optics and contributing to the
for the N-band observations. The initial engineering design of the adaptive optics
The activities at ESO that support the plan was to use the Aquarius detector modules based on their knowledge of the
development of the instruments for the that has been used on-sky with the ELT and experience from the Adaptive
ELT take a number of different forms. To VLT Imager and Spectrometer for mid- Optics Facility upgrade programme. ESO
ensure that ESO meets its commitments InfraRed (VISIR). However, the technology is also leading an effort to coordinate the
for the delivery of the instruments, a dedi- of the new GeoSNAP detector from expertise of all the groups working on
cated follow-up team of scientists, man- Teledyne-E2V is now sufficiently ready SCAO for the ELT, including for the tele-
agers and engineers across all disciplines that the decision to switch to this detec- scope, to explore common solutions for
is assigned to work with each instrument tor was taken after the METIS PDR. Sim- the calibration of these systems.
team. The role of this follow-up team is to plifications to the instrument design come
support the consortia with their expertise from this change but, most importantly, ESO maintains an overview of all of the
and also with understanding the interface the observing efficiency in the N-band systems on the telescope to ensure a
to and performance of the telescope. This imaging mode, where many of the impor- fully working system and is responsible
team also provides each instrument con- tant science cases in exoplanets will be for the interface from all instruments to
sortium with guidance on the application tackled, is expected to be many orders of the observatory and between MAORY
of the ESO standards. Standardisation of magnitude higher than with the design and its client instruments. One of the
hardware and software across the obser- using the Aquarius detector. ESO leads challenges facing both the instrument
vatories is crucial for cost- and time- the work package for the GeoSNAP consortia and ESO is the parallel devel-
effective operation and maintenance of detector that will be tested at the METIS opment of the telescope and the instru-
the telescope(s) and instruments and is a consortium partners the Max Planck mentation. The agreements that have
significant development activity for ESO. Institute for Astronomy and the University been signed with the instrument consor-
The ELT standards include cryogenic of Michigan. Finally, an update of the tia include formal documentation describ-
components, control and dataflow soft- standard detector controller, the Next ing the interface to the telescope systems
ware, instrument control electronics, real- Generation Controller (NGC), to a new and the requirements for the instruments.
time computing and wavefront sensor edition (NGCII) with enhanced perfor- Progress with the construction of the tel-
cameras. The standards have been either mance and matching the interface escope is continuing at our industrial
adopted or extended from the Paranal requirements of the new telescope is partners in Europe and in Chile. With over
Observatory standards, or are new devel-
opments that may also be adopted by
new instruments for Paranal when that is
HIRES METIS (IFU)
Spectroscopy resolving power
technically feasible. 100 000
Engineers and scientists also work within
the consortia to deliver specific compo- HARMONI
MOSAIC
nents or expertise and so ESO is also an (single IFU)
associate member of each instrument 10 000
consortium. ESO has world-leading
expertise in detector technology and tra- MICADO (single slit)
ditionally delivers the science detectors
METIS (slit) METIS (slit)
with standard detector controllers to the
instruments on the VLT, and the same 1000
concept has been adopted for the
ELT instruments. For its optical mode,
Imaging
MICADO METIS METIS
Figure 2. Parameter space for astronomical observa-
tions provided by the first-light and planned instru- 0.5 1.0 2.0 5.0 10.0
ments on the Extremely Large Telescope. Wavelength (µm)
The Messenger 182 | 2021 5
ELT Instrumentation Ramsay S. et al., Instrumentation for ESO’s Extremely Large Telescope
Figure 3. The instru-
ments on the Nasmyth
platform.
95% of the material budget spent, many Part of the system-level activity at ESO detector effect characterisation); and
components are in the manufacturing is keeping an up-to-date model of the end-to-end modelling.
phases, including the many mirror seg- instruments on the Nasmyth platform, as
ments and their mechanical supports the instruments themselves and the tele-
for the main mirror, the remaining opto- scope main structure and prefocal station Acknowledgements
mechanical components and parts of designs evolve. This model allows ESO Many more people than those listed as authors on
the dome and main structure. Significant and the instrument consortia to explore this paper contribute to the development of the
work has been carried out on site, includ- how to access various parts of the sys- instruments for ESO’s ELT. In particular, the impor-
ing the dome foundations on Cerro tem during installation and maintenance, tance of the work of the > 50 members of the
follow-up team at ESO should not be underesti-
Armazones and a new technical facility permits the dynamical modelling of the mated. The authors would like to acknowledge the
as part of the Paranal observatory. As the system under earthquake conditions and contribution of all those at ESO and in the commu-
telescope design evolves, a balance is provides an all-important check that the nity who are participating directly and indirectly in
sought between updating the interface instruments and other items on the this exciting endeavour.
information and maintaining the commit- Nasmyth platform do not occupy the
ment to the numbers in the formal docu- same physical space or attachment References
mentation. An informal, but controlled, points to the Nasmyth floor. The latest
exchange of information underpins the version of this layout is shown in Figure 3. De Zeeuw, T., Tamai, R. & Liske, J. 2014,
The Messenger, 158, 3
collaborative style that both ESO and the Hammer, F., Kaper, L. & Dalton, G. 2010,
consortia wish to maintain while develop- Looking towards the future operation of The Messenger, 140, 36
ing the most complex and costly instru- the ELT, a number of working groups4 on Le Fèvre, O. et al. 2010, The Messenger, 140, 34
ments yet built for the most ambitious specific topics have been set up. Mem- Morris, S. & Cuby, J.-G. 2010, The Messenger,
140, 22
ground-based telescope ever. Work- bership of the working groups is open to Origlia, L., Oliva, E. & Maiolino, R. 2010,
shops at ESO on the telescope and anyone with an interest in contributing to The Messenger, 140, 38
instrument operations concepts, on the the future scientific success of the ELT, Pasquini, L. et al. 2010, The Messenger, 140, 20
alignment and verification of the instru- whether from ESO, from the instrument
ments and on instrument software (pipe- consortia or from the community in gen- Links
line, control and real-time control) have eral. The topics so far under discussion
offered great opportunities for the are: preparing for ELT observations (from 1
ESO’s Extremely Large Telescope (ELT): elt.eso.org
2
exchange of the most up-to-date infor- observation preparation to execution); The Thirty Meter Telescope (TMT): www.tmt.org
3
The Giant Magellan Telescope (GMT):
mation between experts on the ESO and calibrations (including standard stars and www.gmto.org
instrument teams. astro-weather); calibration improvements 4
ELT Working Groups: elt.eso.org/about/
and post-processing (including point workinggroups/
spread function reconstruction and
6 The Messenger 182 | 2021
ELT Instrumentation DOI: 10.18727/0722-6691/5215
HARMONI: the ELT’s First-Light Near-infrared and Visible
Integral Field Spectrograph
Niranjan Thatte 1 performance and good sky coverage, widths), chemical abundances and
Matthias Tecza 1 respectively (AO) capability has recently composition (via emission and absorption
Hermine Schnetler 2 been added for exoplanet characterisa- line ratios) and the physical conditions
Benoit Neichel 3 tion. A large detector complement (temperature, density, presence of shocks)
Dave Melotte 2 of eight HAWAII-4RG arrays, four of the emitting region (via line diagnostics).
Thierry Fusco 3, 4 choices of spaxel scale, and 11 grating In addition, specialist capabilities such
Vanessa Ferraro-Wood 1 choices with resolving powers ranging as molecular mapping for high contrast
Fraser Clarke 1 from R ~ 3000 to R ~ 17 000 make observations, or the use of deconvolution
Ian Bryson 2 HARMONI a very versatile instrument with knowledge of the point spread func-
Kieran O’Brien 5 that can cater to a wide range of tion (PSF) from AO telemetry extend the
Mario Mateo 6 observing programmes. areas where HARMONI will make a huge
Begoña Garcia Lorenzo 7 impact. Some examples are showcased
Chris Evans 2 in the last section of this article.
Nicolas Bouché 8 About HARMONI
Santiago Arribas 9
and the HARMONI Consortium a HARMONI will provide the ELT’s work- Spatial and spectral grasp
horse spectroscopic capability at first
light. A visible and near-infrared integral Figure 1a shows the spatial layout of the
1
epartment of Physics, University
D field spectrograph (IFS), it provides a HARMONI field of view (FoV) at its four
of Oxford, UK “point-and-shoot” capability to simultane- different spaxel scales, one of which
2
United Kingdom Astronomy Technology ously obtain a spectrum of every spaxelb may be selected on the fly. At any spaxel
Centre (UKATC), Edinburgh, UK over a modest field of view. Several differ- scale, HARMONI simultaneously observes
3
L aboratoire d’Astrophysique ent flavours of adaptive optics ensure spectra of ~ 31 000 spaxels in a con
de Marseille (LAM), France (near) diffraction-limited spatial resolution tiguous rectangular field. The common
4
Département d’Optique et Techniques of ~ 10 milliarcseconds over most of the wavelength range in each data cube is
Avancées (DOTA), Office National sky. ELT+HARMONI will transform the ~ 3700 pixels long, after accounting for
d’Etudes et de Recherches Aérospatial landscape of observational astronomy the stagger between adjacent slitlets and
(ONERA), Paris, France by providing a big leap in sensitivity and slit curvature. The spaxel scales range
5
Physics Department, Durham resolution — a combination of the ELT’s from 0.06 × 0.03 arcseconds per spaxel,
University, UK huge collecting area, the exquisite spatial limited by the focal ratios achievable in
6
Department of Astronomy, University resolution provided by the AO, and large the spectrograph cameras, to 4 × 4 milli-
of Michigan, USA instantaneous wavelength coverage cou- arcseconds per spaxel, set to Nyquist
7
Instituto de Astrofísica de Canarias (IAC) pled with a range of spectral resolving sample the ELT’s diffraction limit in the
and Departamento de Astrofísica, powers (R ~ 3000 to 17 000). NIR H band. Two other intermediate
Universidad de La Laguna, Tenerife, scales of 10 × 10 milliarcseconds per
Spain Over the last couple of years, HARMONI spaxel and 20 × 20 milliarcseconds per
8
Centre de Recherche Astrophysique has added substantially to the core spaxel allow the user to optimise for sensi-
de Lyon (CRAL), France instrument. The LTAO capability is part tivity, spatial resolution or FoV, as required.
9
Centro de Astrobiología – Instituto of the baseline, as is a high-contrast AO A larger FoV is particularly desirable when
Nacional de Técnica Aeroespacial, (HCAO) mode that aims to enable direct using the “nod-on-IFU” technique to
Consejo Superior de Investigaciones spectroscopy of extra-solar planetary achieve accurate sky background sub-
Científicas (CAB-INTA/CSIC), Madrid, companions. The University of Michigan traction, as it involves positioning the
Spain has joined as a new partner, providing object alternately in each half of the FoV.
a much needed cash injection, while the
Institut de Planétologie et d’Astrophysique The versatility in choice of plate scale
The High Angular Resolution Monolithic de Grenoble (IPAG) is funding the hard- is complemented by a large choice of
Optical and Near-infrared Integral field ware for HCAO. wavelength ranges and spectral resolving
spectrograph (HARMONI) is the visible powers, as shown in Figure 1b. HARMONI
and near-infrared (NIR), adaptive-optics- HARMONI is equally suited to spatially uses Volume Phase Holographic (VPH)
assisted, integral field spectrograph for resolved spectroscopy of extended tar- gratings for high efficiency. Each grating
ESO’s Extremely Large Telescope (ELT). gets and of point sources, particularly if has a fixed wavelength range, so needs
It will have both a single-conjugate their positions are not precisely known to be physically exchanged to change
adaptive optics (SCAO) mode (using (for example, transients), or if they are observing band. One of eleven different
a single bright natural guide star) and located in crowded fields. The data cube gratings can be chosen, which between
a laser tomographic adaptive optics obtained from a single integral field expo- them provide three different resolving
(LTAO) mode (using multiple laser guide sure can yield information about the powers (R ~ 3000, 7000 and 17 000)
stars), providing near diffraction-limited source morphology (via broad- or narrow- spanning the various atmospheric win-
hyper-spectral imaging. A unique high- band images), spatially resolved kinemat- dows in the NIR (atmospheric transmis-
contrast adaptive optics with high ics and dynamics (via Doppler shifts and sion is shown in grey in Figure 1b).
The Messenger 182 | 2021 7
ELT Instrumentation Thatte N. et al., HARMONI
a) Spaxel c) 50
30 mas 20 mas 10 mas 4 mas
60 mas
Field-of-view
6.12 arcsec
0.3 40
4.08 arcsec
0.82 arcsec
2.04 arcsec
9.12 arcsec 3.04 arcsec 1.52 arcsec 0.61 arcsec
Declination + 2.17 (degrees)
For non-AO and visible For optimal sensitivity Best combination for Highest spatial
observations (faint targets) sensitivity and resolution
Strehl ratio (%)
spatial resolution (diffraction limited)
1 milliarcsecond (mas) = 0.001 arcsec 0.2
Grating resolutions
b) 32 000
Atmosphere
16 000 VIS 20
Resolving power
IzJ
HK 0.1
8000 Iz
J
H
K
4000 10
z-high
H-high
K-high1
2000 K-high2 0.0
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 0.0 0.1
Wavelength (μm) Right ascension + 150.05 (degrees)
Figure 1. a) Spatial layout of the HARMONI science Adaptive optics flavours information from the six lines of sight to
field, showing the spaxel sizes and fields of view
reconstruct the wavefront aberration for
at the four different spaxel scales. b) Spectral cover-
age and resolving power ranges for each of the The ELT is an adaptive telescope, with the on-axis path, and commands M4 and
11 HARMONI grating choices. The atmospheric M4 (a deformable mirror with over 5000 M5 to the appropriate shapes to eliminate
transmission is shown in grey. c) Expected AO per- actuators) and M5 (a fast tip-tilt mirror) the effect of the turbulence, providing a
formance (Strehl ratio) for the COSMOS deep field,
providing active correction of atmos- near diffraction-limited corrected wave-
observed with HARMONI LTAO in good seeing con-
ditions (0.43 arcseconds), illustrating the sky cover- pheric turbulence. The sensing of the front to the IFS.
age achieved for a typical patch of sky. wavefront aberrations is done by the sci-
ence instruments — better rejection of It is not possible to measure the image
common-mode disturbances such as flex- motion with LGS, so a separate natural
A fixed-length spectrum implies a natural ure and vibrations is achieved by splitting guide star (NGS) is needed to sense tip-
compromise between instantaneous the wavefront sensing light as close to the tilt and focus. A single off-axis NGS is
wavelength coverage and resolving power. science focal plane as possible. The sensed by HARMONI’s NGS System
One grating provides coverage at visible scheme used for wavefront sensing leads (NGSS), with a probe arm that patrols a
wavelengths (V and R bands), requiring a to HARMONI’s four distinct operating 1-arcminute-radius field centred on the
different set of detectors (CCDs instead modes: LTAO, SCAO, HCAO, and noAO — IFS FoV. The NGS position and focus are
of the HgCdTe arrays used in the NIR). the last providing no adaptive optics cor- sensed at several hundred Hz in the H
However, as AO correction works well rection of atmospheric turbulence. and K bands, while a slow “Truth Sensor”
only at longer NIR wavelengths, the spatial uses the J-band light from the same star
resolution achieved at visible wavelengths In LTAO operation, six laser guide star to eliminate any low-order wavefront
is close to seeing-limited, making the (LGS) sensors, each with 78 × 78 sub- errors introduced by the LGS. The NGSS
large spaxel count somewhat superflu- apertures, measure the wavefront aberra- is able to operate with stars as faint as
ous. Consequently, only half the FoV is tions at 500 Hz from six sodium laser HAB = 19, so that HARMONI’s LTAO sys-
offered at visible wavelengths, at all stars. The laser stars are located in an tem can provide excellent sky coverage
spaxel scales. asterism with a diameter of ~ 1 arcminute, — 75% of the sky at the south Galactic
which provides the best compromise pole (SGP) with Strehl exceeding 30% in
between peak performance and robust- the K band under median conditions of
ness to changing atmospheric parame- atmospheric turbulence (see Figure 1c for
ters. HARMONI’s AO Control System an example of LTAO sky coverage).
(AOCS) stitches together the wavefront
8 The Messenger 182 | 2021
Even better performance may be combination of a pupil-plane apodiser at half maximum (FWHM) of the seeing.
obtained by using HARMONI’s SCAO and a focal-plane mask. Because of 2 × 1 and 4 × 1 binning along the spatial
system, provided a single, bright, natural uncorrected atmospheric differential axis can be used to reduce readout times
guide star is present within 15 arcseconds refraction (chromatic beam shift), it is not for the CCD detectors, creating effective
of the science target of interest. SCAO possible to use classical coronagraphs to spaxels of 0.06 × 0.06 arcseconds and
can also deal with extended objects improve contrast. The novel design by 0.06 × 0.12 arcseconds, respectively, that
as AO reference “stars”, with slightly Carlotti et al. (2018) achieves good rejec- are a better match to the seeing FWHM.
degraded performance, as long as the tion of starlight — the goal being (post-
reference is less than 2.5 arcseconds processed) contrasts of > 10 6 at separa-
in diameter. Unlike the LTAO system tions < 0.2 arcseconds — whilst enabling Instrument description
(which uses an off-axis NGS), SCAO inner working angles (IWA) of less than
uses a dichroic that sends light in the 100 milliarcseconds for IFS spectroscopy. Figure 2b shows an overview CAD model
700–1000 nm range to a pyramid wave- HCAO works only with an on-axis NGS. of the HARMONI instrument. The instru-
front sensor operating at 500 Hz, with It uses the pyramid wavefront sensor of ment is ~ 8 m tall, and has a footprint of
longer wavelengths (1000–2450 nm) the SCAO system for sensing wavefront 5 × 6 m and a total weight of approxi-
available for spectroscopy with the IFS. aberrations, with a second ZELDA wave- mately 36 tonnes. The opto-mechanics
Both on-axis and off-axis NGS may be front sensor (N’Diaye et al., 2016) for of the IFS consists of the pre-optics scale
used. Optimal performance is achieved improved sensitivity in the high-Strehl changer, the integral field unit (IFU) and
for stars down to V = 12, with a limiting regime. Angular Differential Imaging (ADI) four spectrograph units. The IFU re-
magnitude of V ~ 17. A second SCAO will also be employed to reduce the arranges the light from the field into four
dichroic is available, albeit with a reduced impact of quasi-static speckles. Conse- 500-mm pseudo long slits, which form
patrol field of 4 arcseconds in diameter, quently, the HCAO mode drives the IFS the input to the four spectrograph units.
with a cut-in wavelength of 800 nm for rotator to track the pupil, rather than field The IFS opto-mechanics resides in a
spectroscopy, allowing observations that tracking as employed in all other modes. large cryostat, about 3.26 m in diameter
use z-band stellar absorption features as and 4 m tall (a cutaway view is shown in
diagnostics. At wavelengths where AO correction is Figure 2a), at a constant operating tem-
expected to be poor, or when AO cannot perature of 130 K to minimise thermal
The HCAO mode adds a high-contrast be used owing to weather or technical background. The NIR detectors (eight
capability to HARMONI, using a constraints, HARMONI’s noAO mode can 4096 × 4096-pixel HAWAII 4RG arrays)
provide “seeing-limited” performance. are operated at the lower temperature of
Figure 2. a) Cutaway CAD model of the HARMONI The noAO mode utilises a faint (I < 23) 40 K. The instrument rotator and cable
cryostat (ICR), situated on the instrument rotator
and cable wrap (IRW). The view shows the main
natural star for slow (~ 0.1 Hz) secondary wrap (IRW) allow the entire cryostat to
opto-mechanical components of the integral field guiding, eliminating slow drifts of the rotate about a vertical axis to follow field
spectrograph (IFS), namely the IFS pre-optics (IPO), instrument focal plane and ensuring rotation at the ELT’s Nasmyth focus. The
the integral field unit (IFU), and the spectrographs accurate pointing. This mode is typically vertical rotation axis guarantees an invari-
(ISP). b) overall CAD assembly of HARMONI, with the
various systems comprising the instrument coloured
expected to be used with the visible grat- ant gravity vector, improving the instru-
differently. The LSS is the LGSS Support Structure. ing and the coarsest spaxel scale, as all ment’s stability by minimising flexure.
Other acronyms are explained in the text. scales heavily oversample the full width
a) b) LGSS
IPO
LSS
FPRS
ICR ICR cold structure CM
ISS top frame
IFU
NGSS
IFS
rotating ISP
electronics ISS
cabinets main
frame
ICR
IFS
electronics
cabinets
IRW
IRW
The Messenger 182 | 2021 9
ELT Instrumentation Thatte N. et al., HARMONI
1 × 10 7 Figure 3. a) Reconstructed images of Io, observed
a)
with HARMONI at a scale of 4 × 4 milliarcseconds,
without deconvolution. The bottom image shows
two volcanic hot spots that dominate the NIR emis-
8 × 10 8 sion, while the top image is in a quiescent state.
Simulated spectra of four hot-spots at different tem-
peratures ranging from 600 K to 1200 K are also
Flux (electrons)
6 × 10 8 shown. b) Reconstructed image and spectrum
of a simulated Type-Ia supernova in a z ~ 3 galaxy,
located 0.2 arcseconds from the galaxy nucleus.
c) z ~ 6 galaxy from the NEW HORIZON cosmologi-
4 × 10 8 cal simulation, and its mock observation with ELT+
HARMONI. The spectrum shows a clear detection of
the He II line from Pop III stars, in a 10-hr exposure.
2 × 10 8
b) 0
1.6 1.8 2.0 2.2 2.4
Wavelength (μm)
b) log(Flux) in electrons
10 2 101 10 0 10 –1 10 –2 10 –3 10 –4 Rest wavelength (Å) at z = 3.0000
4000 4500 5000 5500 6000
0
10 0.10
20
Fื (normalised)
0.05
Pixels
30
40
0.00
50
–0.05 sn_observed
60 SN 1981B max
0 10 20 30 40 50 60 1.6 × 104 1.8 × 104 2.0 × 104 2.2 × 104 2.4 × 104
Pixels Observed wavelength (Å)
Σgas (M pc –2) N He II 1640 (electrons)
c)
101 10 2 10 3 10 2 10 3
1.0 1.0
25 000
G5, z = 6
G5, z = 6 Post – HSIM
FWHM = 80.7 ± 0.4 km s –1 0.8
N (× 10 –5 electrons s –1)
0.5 20 000 Npeak /Ncont. = 15.49 ± .07
Transmission
Spaxel scale: 10 × 10
15 000 0.6
y (kpc)
0.0
10 000 0.4
–0.5
5000 0.2
50 mas
–1.0 0 0.0
–1.0 –0.5 0.0 0.5 1.0 –1.0 –0.5 0.0 0.5 1.0 1.149 1.150 1.151 1.152 1.153 1.154 1.155
x (kpc) λ (μm)
The NGSS is located on top of the IFS top of the cryostat and the NGSS. Both just past the instrument slow shutter,
cryostat and co-rotates with it. It houses the FPRS and NGSS are maintained in a close to where telescope light enters the
the natural guide star sensors for all four dry gas environment at a constant tem- instrument, at a beam height of 6 m
operating modes. As the telescope’s perature of –15 degrees C, reducing above the Nasmyth platform. The first
back focal distance is insufficient to thermal background for improved K-band element in the instrument light path is
relay the telescope light directly into the sensitivity and minimising thermal drifts. the LGS dichroic, which sends light at
upward-looking cryostat, a focal-plane 589 nm from the ELT’s six LGS to the
relay system (FPRS) re-images 2 arcmin- The LGS System (LGSS) and the LGSS. As the LGS asterism is projected
utes of the telescope focal plane to the Calibration Module (CM) are located from the periphery of the ELT primary
10 The Messenger 182 | 2021mirror (M1), it co-rotates with the tele- non-destructive readout saved in the required exposure time or even the feasi-
scope pupil, and the LGSS needs its own archive. AO telemetry data, useful for bility of the planned observation. It also
de-rotator to compensate. The CM can reconstructing the PSF during the expo- allows the user to develop and test the
insert light from calibration lamps via fold sure, will also be archived. analysis tools required. The HSIM code is
mirrors into the beam path, mimicking publicly available2.
the telescope f-ratio and pupil location. It Science calibrations needed by the data
provides line and continuum sources for reduction pipeline, such as arc lamp HSIM predicts point source sensitivities
all science and technical calibrations. The exposures for wavelength calibration, (5σ, 5 hr, 2 × 2-spaxel extraction aper-
Instrument Static Structure (ISS) provides detector bias and dark frames, flat fields ture) of JAB = 25.6, HAB = 26.8, KAB = 25.9
a robust mechanical structure and and vertical line and pinhole masks, will in LTAO mode, with SCAO performance
access to all instrument systems. be carried out the morning after the of JAB = 26.2, HAB = 27.0, KAB = 26.0 at
observations, as is typical for VLT instru- R ~ 3000. The point source sensitivities
ments. ELT instruments are required to do not convey the full picture, so we have
Operation and calibration be light-tight, so calibrations can happen used HSIM to carry out detailed simula-
in parallel for all instruments. With four tions showcasing a few planned observa-
HARMONI is conceptually simple to oper- observing modes, 4 choices of spaxel tions with HARMONI. These range from
ate, as it provides a “point-and-shoot” scale, and 11 grating settings, the number objects in our own Solar System to the
capability. The user selects one of four of distinct configurations needing calibra- most distant galaxies at z ~ 6–10.
operating modes: noAO, SCAO, HCAO tion exceeds 100. Consequently, only the
or LTAO. In addition, the user must configurations used during the night will Jupiter’s moon Io is the most volcanically
choose a setting that specifies a choice be calibrated the following morning. Sci- active body in the Solar System. Groussin
of spaxel scale, grating and, optionally, ence calibrations and additional monitor- et al. (in preparation) have simulated ELT
other user-selectable items (for example, ing calibrations will be used for “health- observations of Io’s hotspots. They show
SCAO dichroic, or apodiser) and the checks” (to monitor trends in instrument that it is possible to distinguish between
instrument is configured accordingly. performance). Efforts will be made to mini- sulphurous and ultra-mafic composition
Accurate pointing is assured by specify- mise night-time calibrations (telluric or of the ejecta by measuring the ejecta’s
ing offsets of the science field centre flux standards) wherever possible. Meth- temperature (see Figure 3a) from their
from the natural guide star. As a conse- ods that use model-based calibrations NIR spectra, using HARMONI’s SCAO
quence, the default acquisition sequence instead are being actively investigated mode providing near diffraction-limited
does not require an acquisition exposure by a number of ESO working groups. spatial resolution.
with the IFS — once the guide star is
acquired and all control loops are closed, Bounissou et al. (2018) have shown that
the first science exposure can commence Performance HARMONI LTAO can provide direct spec-
straight away. Thanks to the unprece- troscopic classification of a supernova
dented spatial resolution of the ELT, the We have developed a python simulator, in a galaxy at z ~ 3 in a 3-hr observation,
accuracy of information needed for guide HSIM1, to provide prospective users with up to 2 months past maximum light (see
stars (proper motion, colour, etc.) is much the ability to quantitatively assess the effi- Figure 3b), using the Si II feature (at
higher than for the Very Large Telescope cacy of their proposed observing pro- 400 nm in the rest frame). Confirming
(VLT). With the faint guide stars which gramme. HSIM (Zieleniewski et al., 2015) type Ia supernovae spectroscopically for
can be used by HARMONI, catalogues is a “cube-in, cube-out” simulator that a small sub-sample will allow studies of
may not suffice and pre-imaging of the mimics the effects of atmosphere, tele- cosmic expansion rates to be pushed to
field might be needed in some cases. scope, instrument and detector, including substantially higher redshifts.
the strongly wavelength-dependent, non-
Observing templates will have a similar axisymmetric AO PSF. The user can ana- We have used the adaptive mesh refine-
look and feel to those of other VLT NIR lyse the output cube as if it were the out- ment cosmological simulations from the
IFS, and will include a variety of sky- put of the instrument pipeline for a real NEW HORIZON suite (Dubois et al., 2020)
subtraction strategies such as “offset observation, as it incorporates noise from to simulate studies of high-z galaxies with
to blank sky”, “nod-on-IFU” or “stare”, all sources, including shot noise from HARMONI in a spatially resolved manner.
together with small jitters to work around thermal background and night-sky emis- Using cosmological simulations that cre-
bad or hot pixels. Mosaicking will also be sion, detector readout noise and dark ate galaxies at high spatial resolution
supported in the usual way, as will non- current. Detector systematics and the commensurate with HARMONI’s observa-
sidereal tracking in LTAO and noAO impact of sky subtraction can also be tional capabilities (~ 100 pc at z ~ 2–10) is
modes (in SCAO and HCAO mode, the included if desired. Through detailed preferred because the objects have mor-
only non-sidereal observation possible analysis of the output cube, the astrono- phologies and kinematic and dynamical
is when the AO reference “star” is itself mer can derive uncertainties and confi- properties consistent with the observed
non-sidereal). NIR long exposures (typical dence levels for the derived physical ensemble population at high redshifts,
for spectroscopy of faint targets) will use parameters from the observation, rather and have well understood input physics
Sample-Up-The-Ramp (SUTR) readout than just the signal-to-noise ratio per consistent with known laws and cosmo-
to minimise readout noise, with every spaxel (or pixel), thus quantifying the logical evolution (Richardson et al., 2020).
The Messenger 182 | 2021 11ELT Instrumentation Thatte N. et al., HARMONI
Grisdale et al. (2020) have used NEW from a substantial fraction of the mock Olivier Groussin (Io simulations) and Kearn Grisdale
(Pop III simulations). We are also grateful to James
HORIZON simulations, post-processed galaxies in a 10-hr exposure (Figure 3c).
Carruthers, Neil Campbell, and David Montgomery
using the CLOUDY radiative transfer However, to be certain that the line for CAD views. Miguel Pereira-Santaella is the
code (Ferland et al., 2017) to show indicates the presence of Pop III stars author of HSIM and we thank him for the sens i-
that HARMONI LTAO could detect the would require ancillary observations of tivity computations.
presence of the first stars (Pop III stars) in the H-alpha line from these objects to
galaxies at very high redshifts (z = 3–10). measure the He II to H-alpha ratio, prob- References
The existence of Pop III stars has not ably using the James Webb Space
been observationally confirmed up to Telescope, given the high redshifts Bounissou, S. et al. 2018, MNRAS, 478, 3189
Carlotti, A. et al. 2018, Proc. SPIE, 10702, 107029N
now, although several attempts have involved.
Dubois, Y. et al. 2020, arXiv:2009.10578
been made and some excellent candi- Ferland, G. J. et al. 2017, Revista Mexicana
dates have been identified. Given their de Astronomía y Astrofísica, 53, 385
primordial composition with no heavy Acknowledgements Grisdale, K. et al. 2021, MNRAS, 501, 5517
N’Diaye, M. et al. 2016, Proc. SPIE, 9909, 99096S
elements, Pop III stars are expected to HARMONI work in the UK is supported by the Richardson, M. et al. 2020, MNRAS, 498, 1891
be substantially more massive than their Science and Technology Facilities Council (STFC) Zieleniewski, S. et al. 2015, MNRAS, 453, 3754
metal-rich cousins. Consequently, they at the UK Astronomy Technology Centre (UKATC),
should burn much hotter, and have a Rutherford Appleton Laboratory (RAL), University of
Oxford (grants ST/N002717/1 and ST/S001409/1) Links
much higher ultraviolet flux, capable of and Durham University (grant ST/S001360/1), as part
ionising not only hydrogen but also helium of the UK ELT Programme. In France, the HARMONI 1
HSIM simulator: https://harmoni-elt.physics.ox.ac.
in the surrounding gas (H II region). The Project is supported by the CSAA-CNRS/INSU, uk/Hsim.html
strength of the He II 164 nm line is thus ONERA, A*MIDEX, LABEX LIO, and Université 2
HSIM code: https://github.com/HARMONI-ELT/HSIM
Grenoble Alpes. The IAC and CAB (CSIC-INTA)
a good observational diagnostic for the acknowledge support from the Spanish MCIU/AEI/
presence of Pop III stars. Despite the FEDER UE (grants AYA2105-68217-P, SEV-2015- Notes
large luminosity distance of these very 0548, AYA2017-85170-R, PID2019-107010GB-100,
high-redshift star forming regions, the CSIC-PIE201750E006, and PID2019-105423GA-I00) a
The full list of HARMONI Consortium members can
and from the Comunidad de Madrid (grant 2018-T1/ be found at https://harmoni-elt.physics.ox.ac.uk/
ELT’s huge collecting area, coupled with TIC-11035). consortium.html
the exquisite spatial resolution provided b
Spaxel stands for SPAtial piXEL, to distinguish it
by HARMONI LTAO, would detect the The authors would like to acknowledge contributions from a pixel of the spectrograph detector.
He II feature with good signal-to-noise from Sophie Bounissou (supernova simulations),
ESO/SPECULOOS Team/E. Jehin
If you had a brand new
state-of-the-art tele-
scope facility, what
would you look at first?
Researchers at the
SPECULOOS Southern
Observatory — which
comprises four small tel-
escopes, each with a
1-metre primary mirror
— chose to view the
Lagoon Nebula. This
magnificent picture is
the result, and is one of
the SPECULOOS’ first
ever observations.
12 The Messenger 182 | 2021ELT Instrumentation DOI: 10.18727/0722-6691/5216
MAORY: A Multi-conjugate Adaptive Optics RelaY for ELT
Paolo Ciliegi 1 Andrew Rakich 1 diameter ~ 60 arcseconds, with pretty
Guido Agapito 1 Patrick Rabou 3 homogeneous performance over the
Matteo Aliverti 1 Edoardo Redaelli 1 whole FoV.
Francesca Annibali 1 Matt Redman 2
Carmelo Arcidiacono 1 Marco Riva 1 MAORY is designed to support two dif-
Andrea Balestra 1 Sylvain Rochat 3 ferent instruments, each with the same
Andrea Baruffolo 1 Gabriele Rodeghiero 1 optical quality and with a gravity-invariant
Maria Bergomi 1 Bernardo Salasnich 1 port. One of these two instruments will
Andrea Bianco 1 Paolo Saracco 1 be the Multi-adaptive optics Imaging
Marco Bonaglia 1 Rosanna Sordo 1 CamerA for Deep Observations (MICADO)
Lorenzo Busoni 1 Marilena Spavone 1 near-infrared camera (Davies et al., 2018),
Michele Cantiello 1 Marie-Hélène Sztefek 3 while the second one is as yet undefined.
Enrico Cascone 1 Angelo Valentini 1 The SCAO module is being developed
Gaël Chauvin 3 Eros Vanzella 1 within the MICADO consortium with con-
Simonetta Chinellato 1 Christophe Verinaud 4 tributions from MAORY and is described
Vincenzo Cianniello 1 Marco Xompero 1 in Davies et al. (p. 17). The MAORY pro-
Jean-Jacques Correia 3 Simone Zaggia 1 ject is now in its Phase B stage and is
Giuseppe Cosentino 1 progressing towards its Preliminary
Massimo Dall’Ora 1 Design Review in early 2021.
Vincenzo De Caprio 1 1
INAF, Italy
Nicholas Devaney 2 2
NUIG, Galway, Ireland
Ivan Di Antonio 1 3
CNRS/INSU, Grenoble, France Science drivers
Amico Di Cianno 1 4
ESO
Ugo Di Giammatteo 1 The scientific application of the SCAO
Valentina D’Orazi 1 mode will be limited by the need for a
Gianluca Di Rico 1 The Multi-conjugate Adaptive Optics bright (approximately V ≤ 16 magnitudes)
Mauro Dolci 1 RelaY (MAORY) is the adaptive optics star within few arcseconds of the scien-
Sylvain Doutè 3 (AO) module for the Extremely Large tific target, while the MCAO mode will
Cristian Eredia 1 Telescope (ELT) that will provide two make use of three natural guide stars
Jacopo Farinato 1 gravity-invariant ports with the same (NGS) (with H ≤ 21.0 magnitudes) to be
Simone Esposito 1 optical quality for two different client found within an annular patrol field with
Daniela Fantinel 1 instruments. It will enable high-angular- an inner radius of ~ 40 arcseconds and
Philippe Feautrier 3 resolution observations in the near- an outer radius of ~ 160 arcseconds. The
Italo Foppiani 1 infrared over a large field of view three NGS will allow us to correct low-
Enrico Giro 1 (~ 1 arcminute 2) by real-time compensa- order modes of the wavefront distortions,
Laurance Gluck 3 tion of the wavefront distortions caused while the six laser guide stars (LGS) will
Aaron Golden 2 by atmospheric turbulence. Wavefront be used to correct for high-order modes.
Alexander Goncharov 2 sensing is performed using laser and This will make it possible to get AO-
Paolo Grani 1 natural guide stars while the wavefront assisted observations over a large frac-
Marco Gullieuszik 1 sensor compensation is performed by tion of the sky, meeting the system speci-
Pierre Haguenauer 4 an adaptive deformable mirror (DM) in fication for sky coverage (≥ 50% over the
François Hénault 3 MAORY which works together with the whole sky).
Zoltan Hubert 3 telescope’s adaptive and tip-tilt mirrors
Miska Le Louran 4 M4 and M5 respectively. Coupled with MICADO, MAORY will ena-
Demetrio Magrin 1 ble the ELT to perform diffraction-limited
Elisabetta Maiorano 1 observations in the near-infrared. In imag-
Filippo Mannucci 1 Introduction ing mode MAORY + MICADO will provide
Deborah Malone 2 an option with a wide FoV (50.5 × 50.5
Luca Marafatto 1 MAORY will provide the ELT with two arcseconds) at pixel scale of 4 milli-
Estelle Moraux 3 adaptive optics modes: the single- arcseconds and a high-resolution option
Matteo Munari 1 conjugate adaptive optics (SCAO) mode, with a 1.5-milliarcsecond pixel scale over
Sylvan Oberti 4 which provides a very high correction 19 × 19 arcseconds. This will represent a
Giorgio Pariani 1 over a field of view (FoV) of diameter major step forward, with a significantly
Lorenzo Pettazzi 4 ~ 10 arcseconds, with performance rap- better spatial resolution than that of the
Cédric Plantet 1 idly degrading with distance from the Hubble Space Telescope (HST) and even
Linda Podio 1 bright natural star used to probe the the James Webb Space Telescope
Elisa Portaluri 1 wavefront, and a multi-conjugate adap- (which has a pixel scale ~ 30 milliarcsec-
Alfio Puglisi 1 tive optics (MCAO) mode, which provides onds pixel –1). Long-slit spectroscopy will
Roberto Ragazzoni 1 a moderate correction over a FoV of be covered with two settings: a short slit
The Messenger 182 | 2021 13ELT Instrumentation Ciliegi P. et al., MAORY: A Multi-conjugate Adaptive Optics RelaY for ELT
a) b)
NGC 4472 50ೀ 0.2ೀ
Terzan 5 MAD 30ೀ × 18ೀ DSS2
HST
MAORY
HST
MAORY 1ೀ × 1ೀ MAORY
1.0ೀ
DSS2
MAORY
c) Age = 15 Myr HST/F105W Galfit model PSF NGC1705 hosts
YMC 1 px
39
+ fake NGC1705 Muv = –15.6 (31.1) (residuals)
pc
Re = 4 pc (optical) 130 pc
0
YMC: 38
pc
Muv = 15.23
Mass = 7.1 × 10 5 M 1 px
13 pc
8 pc
D1 D1
pc
T1 T1
0
26
z = 6.1
Lensed: HST 1 pix = 30 mas
z=0
Lensed: ELT 1 pix = 4 mas
ELT (MAORY + MICADO)/H band
z = 6.1 PSF HST
Relative counts
0
200
400
600
05
pc 800 UDC/NGC17 1 px PSF ELT
1000 1200 1400 17 pc
800 1000
1200 200 400 600
pc
0
pc
39
pc
pc
15
1 px
15
0
38
pc
1.7 pc
Figure 1. Combination of real and simulated images the MAORY science cases White Book resolved into individual stars. In many
from the MAORY science cases White Book.
available on the MAORY website1. cases they will fall within the range of
a) Terzan 5 as imaged by MAD at VLT and by
MAORY + MICADO. b) NGC 4470 as imaged by resolved systems only thanks to the
HST and MAORY + MICADO. c) 2D and 3D HST Together the science cases address advent of MAORY + MICADO;
images of NGC 1705 and simulations at HST and many of the major questions in – The high-redshift Universe, with the sci-
MAORY + MICADO resolution lensed at z = 6.1.
astrophysics: ence cases addressing the formation of
–P lanetary systems, including cases in structures and cosmology using the
of 0.84–1.48 μm, and a long slit of 1.48– our own Solar System, exoplanets and formidable sensitivity and resolution of
2.46 μm (see Davies et al., p. 17 for a the formation of planetary systems; MAORY + MICADO to probe the very
detailed description of the MICADO –N earby stellar systems, comprising distant Universe and consequently the
observing modes). stars and stellar systems within our own earliest phases of galaxy formation, as
Galaxy and its satellites; well as high-energy phenomena over
The science cases for MAORY + MICADO –T he local Universe, with science cases the range of cosmic distance and time
have been widely explored by the aimed at studying the stellar content made accessible by the ELT.
MAORY science team. A preliminary col- and the structure of distant stellar sys-
lection of the cases studied is reported in tems that can be at least partially
14 The Messenger 182 | 2021You can also read
