Toward the AO for the European ELT
Norbert Hubin
European Southern Observatory
http://www.eso.org/sci/facilities/develop/ao.html
Outlines
 E-ELT Project: Telescope & instrument/AO roadmap
 Pathfinders supporting the ELTs
 Adaptive telescope progresses
 Single & Multi-Conjugate AO for MICADO
 Single conjugate & Laser tomography for HARMONI
 Single conjugate & Laser tomography for METIS
 Conclusions
The E-ELT Project
The Telescope
• 40-m class telescope opticalinfrared telescope
• Segmented primary mirror
• Adaptive Optics assisted telescope
• Multi-LGSs side launched
• Diffraction limited performance:
12mas@K-band
Wide field of view: 10 arcmin
• Mid-latitude site (Amazones/Chile)
• Fast instrument changes
• VLT level of operations efficiency.
The E-ELT Project
Adaptive telescope
4
Adaptive 2.5 m M4 unit for 39 m
4974 contactless actuators in optical
area
Max 160 µm stroke
31.5 mm pitch, triangular pattern
2480/2387 mm diameter
Segmented Zerodur 1.95mm thin shell
(6 petals)
Backplate in Zerodur/SiC TBC
Removable Actuator Brick design (198
bricks)
On board M4 electronics
Remote M4 Control System
Flex joint hexapods for M4
Positioning System
Large bearing + cable wrap for
Nasmyth selector
Mass: 10 tons
Power: 8.4 kW
The E-ELT Project
Instrument Roadmap
Instruments
- First Light
AO
Mode
λ (µm)
Resolution
FoV / Sampling
Add. Mode
E-CAM
– 2023
SCAO,
MCAO
- IMG
- MRS
0.8 – 2.4
BB, NB
3000
53.0” / 3 mas
Astrometry 40mas
Coronography
E-IFU
– 2023
SCAO,
LTAO
- IFU
0.5 – 2.4
4000
10 000
20 000
0.5×1.0” / 4mas
5.0×10.0” / 40mas
Coronography
E-MIDIR
– 2024/2028
SCAO,
LTAO
- IMG
- MRS
- IFU
3 – 13
3 - 13
3-5
BB, NB
5000
100 000
18” / 12 mas
Coronography
Polarimetry
SCAO
- HRS
0.37 – 0.71
0.84 – 2.50
200 000
120 000
0.82”
0.027”×0.5”
Polarimetry
MOAO
Slits
IFUs
IFUs
0.37 – 1.4
0.37 – 1.4
0.8 – 2.45
300- 2500
5000 – 30 000
4000 – 10 000
6.8” / 0.1”
420’ / 0.3”
2” / 40mas
Multiplex ~ 400
Multiplex ~100
Multiplex ~10
Imaging?
EPOL
IFS
0.6 – 0.9
0.95 – 1.65
125 – 20 000
2.0” / 2.3 mas
0.8“ / 1.5 mas
Coronography
Polarimetry
E-HIRES
- 2024/2028
E-MOS
- 2024/2028
E-PCS
- 2027/2030
XAO
0.4”×1.5” / 4 mas
The E-ELT Project
Instrument Roadmap
• 1st Light Instruments
Instruments
- First Light
AO
Mode
λ (µm)
Resolution
FoV / Sampling
Add. Mode
E-CAM
– 2023
SCAO,
MCAO
- IMG
- MRS
0.8 – 2.4
BB, NB
3000
53.0” / 3 mas
Astrometry 40mas
Coronography
E-IFU
– 2023
SCAO,
LTAO
- IFU
0.5 – 2.4
4000
10 000
20 000
0.5×1.0” / 4mas
5.0×10.0” / 40mas
Coronography
E-MIDIR
– 2024/2028
SCAO,
LTAO
- IMG
- MRS
- IFU
3 – 13
3 - 13
3-5
BB, NB
5000
100 000
18” / 12 mas
Coronography
Polarimetry
SCAO
- HRS
0.37 – 0.71
0.84 – 2.50
200 000
120 000
0.82”
0.027”×0.5”
Polarimetry
MOAO
Slits
IFUs
IFUs
0.37 – 1.4
0.37 – 1.4
0.8 – 2.45
300- 2500
5000 – 30 000
4000 – 10 000
6.8” / 0.1”
420’ / 0.3”
2” / 40mas
Multiplex ~ 400
Multiplex ~100
Multiplex ~10
Imaging?
EPOL
IFS
0.6 – 0.9
0.95 – 1.65
125 – 20 000
2.0” / 2.3 mas
0.8“ / 1.5 mas
Coronography
Polarimetry
E-HIRES
- 2024/2028
E-MOS
- 2024/2028
E-PCS
- 2027/2030
XAO
SCAO: single-conjugated AO
MCAO: Multi-Conjugated-AO
MOAO: Multi-Object AO
XAO: Extreme-AO
0.4”×1.5” / 4 mas
LTAO: Laser-Tomographic AO
The E-ELT Project
Instrument Roadmap
• 2nd Pool Instruments
Instruments
- First Light
AO
Mode
λ (µm)
Resolution
FoV / Sampling
Add. Mode
E-CAM
– 2023
SCAO,
MCAO
- IMG
- MRS
0.8 – 2.4
BB, NB
3000
53.0” / 3 mas
Astrometry 40mas
Coronography
E-IFU
– 2023
SCAO,
LTAO
- IFU
0.5 – 2.4
4000
10 000
20 000
0.5×1.0” / 4mas
5.0×10.0” / 40mas
Coronography
E-MIDIR
– 2024/2028
SCAO,
LTAO
- IMG
- MRS
- IFU
3 – 13
3 - 13
3-5
BB, NB
5000
100 000
18” / 12 mas
Coronography
Polarimetry
SCAO
- HRS
0.37 – 0.71
0.84 – 2.50
200 000
120 000
0.82”
0.027”×0.5”
Polarimetry
MOAO
Slits
IFUs
IFUs
0.37 – 1.4
0.37 – 1.4
0.8 – 2.45
300- 2500
5000 – 30 000
4000 – 10 000
6.8” / 0.1”
420’ / 0.3”
2” / 40mas
Multiplex ~ 400
Multiplex ~100
Multiplex ~10
Imaging?
EPOL
IFS
0.6 – 0.9
0.95 – 1.65
125 – 20 000
2.0” / 2.3 mas
0.8“ / 1.5 mas
Coronography
Polarimetry
E-HIRES
- 2024/2028
E-MOS
- 2024/2028
E-PCS
- 2027/2030
XAO
SCAO: single-conjugated AO
MCAO: Multi-Conjugated-AO
MOAO: Multi-Object AO
XAO: Extreme-AO
0.4”×1.5” / 4 mas
LTAO: Laser-Tomographic AO
The E-ELT Project
Instrument Roadmap
• XAO Instrument
Instruments
- First Light
AO
Mode
λ (µm)
Resolution
FoV / Sampling
Add. Mode
E-CAM
– 2023
SCAO,
MCAO
- IMG
- MRS
0.8 – 2.4
BB, NB
3000
53.0” / 3 mas
Astrometry 40mas
Coronography
E-IFU
– 2023
SCAO,
LTAO
- IFU
0.5 – 2.4
4000
10 000
20 000
0.5×1.0” / 4mas
5.0×10.0” / 40mas
Coronography
E-MIDIR
– 2024/2028
SCAO,
LTAO
- IMG
- MRS
- IFU
3 – 13
3 - 13
3-5
BB, NB
5000
100 000
18” / 12 mas
Coronography
Polarimetry
SCAO
- HRS
0.37 – 0.71
0.84 – 2.50
200 000
120 000
0.82”
0.027”×0.5”
Polarimetry
MOAO
Slits
IFUs
IFUs
0.37 – 1.4
0.37 – 1.4
0.8 – 2.45
300- 2500
5000 – 30 000
4000 – 10 000
6.8” / 0.1”
420’ / 0.3”
2” / 40mas
Multiplex ~ 400
Multiplex ~100
Multiplex ~10
Imaging?
EPOL
IFS
0.6 – 0.9
0.95 – 1.65
125 – 20 000
2.0” / 2.3 mas
0.8“ / 1.5 mas
Coronography
Polarimetry
E-HIRES
- 2024/2028
E-MOS
- 2024/2028
E-PCS
- 2027/2030
XAO
SCAO: single-conjugated AO
MCAO: Multi-Conjugated-AO
MOAO: Multi-Object AO
XAO: Extreme-AO
0.4”×1.5” / 4 mas
LTAO: Laser-Tomographic AO
The E-ELT Project
Instrument Roadmap
• Various AO Flavors
Instruments
- First Light
AO
Mode
λ (µm)
Resolution
FoV / Sampling
Add. Mode
E-CAM
– 2023
SCAO,
MCAO
- IMG
- MRS
0.8 – 2.4
BB, NB
3000
53.0” / 3 mas
Astrometry 40mas
Coronography
E-IFU
– 2023
SCAO,
LTAO
- IFU
0.5 – 2.4
4000
10 000
20 000
0.5×1.0” / 4mas
5.0×10.0” / 40mas
Coronography
E-MIDIR
– 2024/2028
SCAO,
LTAO
- IMG
- MRS
- IFU
3 – 13
3 - 13
3-5
BB, NB
5000
100 000
18” / 12 mas
Coronography
Polarimetry
SCAO
- HRS
0.37 – 0.71
0.84 – 2.50
200 000
120 000
0.82”
0.027”×0.5”
Polarimetry
MOAO
Slits
IFUs
IFUs
0.37 – 1.4
0.37 – 1.4
0.8 – 2.45
300- 2500
5000 – 30 000
4000 – 10 000
6.8” / 0.1”
420’ / 0.3”
2” / 40mas
Multiplex ~ 400
Multiplex ~100
Multiplex ~10
Imaging?
EPOL
IFS
0.6 – 0.9
0.95 – 1.65
125 – 20 000
2.0” / 2.3 mas
0.8“ / 1.5 mas
Coronography
Polarimetry
E-HIRES
- 2024/2028
E-MOS
- 2024/2028
E-PCS
- 2027/2030
XAO
SCAO: single-conjugated AO
MCAO: Multi-Conjugated-AO
MOAO: Multi-Object AO
XAO: Extreme-AO
0.4”×1.5” / 4 mas
LTAO: Laser-Tomographic AO
Global vision & walking before running
 All AO systems for E-ELT are challenging & costly:
 Many new concepts are still in demonstration phase or have not been fully
operated on smaller telescopes for science Pathfinders
 Technologies required are often one step behind Dev. needed
 Operation, Control & calibration strategies are still being figured out
crucial effective operation of AO system for science Pathfinders
 Global vision is essential to reduce cost & risks for all
 1 observatory cannot cope with all challenges alone Fair collaboration
is highly desirable: TMT-GMT-ESO-LBT-Gemini-Keck-WHT-SUBARU...
 Reasonable global pathfinding vision, good view of essential
technological bricks & cross fertilization of ideas between teams is vital
•
•
•
•
•
•
Adaptive telescope: MMT- LBT- Magellan -VLT- E-ELT…
MCAO: MAD- Solar MCAO- Gems
GLAO-LTAO: MMT, SAM, MAD, AOF, CANARY
MOAO: Village, CANARY, RAVEN EAGLE
XAO- High contrast: Gemini, VLT, SUBARU, LBT? EPICS
Lasers, DMs, RTC, WFS detectors, smart algorithms, vibration control, operation…
AOF pathfinder
 Single project structure covering all phases  Now in Testing
GRAAL
GALACSI
DSM
ASSIST
4LGSF
UT4 Upgrade
NGC
SPARTA (
Important R&D component embedded in AOF
Project
AO4ELT - Firenze
27/05/2013
12
ESO AOF: Pathfinding Role for EELT
“Soft” benefits:






Hands-on experience with an adaptive telescope
New AO modes: GLAO, LTAO & of course SCAO
Tight error budgets, high Strehl (GALACSI NFM,
ERIS)
Calibration strategy, including on-sky, synthetic
Real Time Computer: AOF SPARTA brought us high
up on learning curve
How to operate an adaptive telescope efficiently
Concrete Benefits:





EELT M4 is directly inspired from the DSM
SAGEM benefits from the synergy of thin shells (DSM, proto M4, M4 monolithic)
The Laser developed and funded by AOF is “as is” usable by EELT
The Launch telescope developed by AOF is “as is” usable by EELT
ESO has delivered a < 1e- RON detector @ 1.35 kHz !!! (with help from
community: Ocam, FirstLight)
Validate control strategy: AOF as 1st step
AOF control/operation strategy
good starting point for end-to-end
control strategy of ELT
 SCAO
 GLAO
 LTAO
 ELT more complex though
 Segmented M1
 5 mirror design to control
 Less rigid structure
 LGS operation more complex
 Telescope metrology overlaps
with AO metrologies
 MCAO with one DM in telescope
Validate end-to-end acquisition sequence (i.e AOF)
TELESCOPE AO DESIGN &
TECHNOLOGY DEVELOPMENT
Adaptive 2.5 m M4 unit for 39 m
4974 contactless actuators in optical area
Max 160 µm stroke
31.5 mm pitch, triangular pattern
2480/2387 mm diameter
Segmented Zerodur 1.95mm thin shell (6
petals)
Backplate in Zerodur/SiC TBC
Removable Actuator Brick design (198
bricks)
On board M4 electronics
Remote M4 Control System
Flex joint hexapods for M4 Positioning
System
Large bearing + cable wrap for Nasmyth
selector
Mass: 10 tons
Power: 8.4 kW
M4 Unit Preliminary Design Contract
 Mirror technology optimization:
 Development of new concepts for more reliable co-located
sensors (more reliable electrical interface, easier
installation) applicable to both glass and SiC M4 Unit
solutions
 New design of Brick interfaces to fulfill SiC manufacturing
uncertainties
 Demonstration prototype design on-going
 Next steps: Demonstration prototype development &
Completion of the Preliminary Design
New Actuator bricks design
The actual design of the brick is the one that will be tested on the updated
demonstration prototype
M4 Demonstration Prototype (DP) design
The DP is representative of most critical aspects of the
M4U: bricks, Reference body design, shell, actuator
pattern, cophasing, actuator/capsens, cooling plant, local
control system.
222 actuators
453.2 x 796 x 300mm
Error budget estimate for M4 unit only
2.5 m M5 Tip-tilt Unit prototype LCS
 Purpose
• Verify architecture principles and ICD towards the contractors, provide worked
example as reference to construction contract.
• Verify our requirements and development standards
• Amend requirements and development standards, if necessary
• Provide environment to verify active damping strategies
Instruments & Modules
SCAO
CAM
MCAO
SCAO
IFU
LTAO(GLAO)
LTAO – not in
cons. phase
MIR
SCAO
23
From Single to Multi-Conjugate AO for MICADO
SCAO: Proposed as part of MICADO, a complementary AO capability for initial highest
performance on compact targets. Also considered as risk mitigation & diffraction limited science
before MAORY arrives (TBC)
 Wavefront sensor (type depending on performance & dynamic range)
M4 adaptive mirror corrector (baseline fitting error 142 nm rms) ~50cm sampling on M1
Additional telescope error budget to be taken into account.
MCAO: MAORY good, uniform performance over full field with high sky coverage. MAORY also
proposes to include a SCAO mode for on-axis peak-Strehl performance.
SCAO Sr(K) = 76%
SCAO Sr(K) = 69%
Courtesy: Le Louarn-ONERA
No telescope WFE
With telescope WFE (very preliminary 42 m)
MAORY Strehl performance (0.8” seeing)







6 LGSs side launched
3 NGSs (IR WFSs)
0.6 µm <  < 2.4 µm
S.R. >50% in K over 2’
Central 1’ clear
DM conjugated at 4km, 12.7km
Two output ports
 Sky coverage Galactic Pole
 No telescope error budget included yet
MAORY ensquared energy performance
Performance to be updated for 39 m telescope
Telescope error budget to be added
MAORY for MICADO on-going work
 Managerial:
 Phase A study Nov 2007 – Dec 2009
 MCAO module approved by ESO as part of first-light instrumentation to serve EELT diffraction-limited camera MICADO; however awaiting from E-ELT funding
 Project plan for next phases under consolidation
 Negotiations between ESO and INAF (lead institute) are well advanced
 INAF is supporting the project through its Directorate of Science
 Current Consortium organization: INAF; Durham Univ; Obs. de Paris/LESIA;
ESO
MAORY related on-going work I
 Consolidation of 20 W Raman fiber laser developed by ESO/TOPTICA
 MAORY optical design trade-offs: alternative DM sizes, ADC, dichroic, LGS
WFSs…
 Sodium density profile measurements on-axis and in FoV (UBC collaboration
 E2V Manufacturing of WFS detector: CMOS 840^2 pixels with 4eRON, 700Hz
 Test controller development for the detector above: LAM & ESO GMT?
 Smart algorithms for MCAO… reconstruction in collaboration with Linz team
1377 act. Piezo DM for SPHERE
with its drive electronics
MAORY related on-going work II
 Laser spot truncation in SH WfSing see Poster Miska et al.
 IR 320x256 eAPD array required for low WFSing in MAORY, LTAO, SCAO?
 Medium size piezo-DM: addressing the recent DM manufacturing
obsolescence problem in collaboration with TMT & CILAS
 Alternative DM solutions: XINETICS, MZA, MG-ADS
 Global collaborative effort to establish a RTC development plan & strategy
for E-ELT AO instruments (U. Durham, LESIA, TNO, MPIA?, ESO)  goal
coordinate RTC efforts with all E-ELT Consortia
Sodium spot elongation truncation using full
tomography information
Triangle: Non Gaussian, 2x2 NGS, Diamond: 6x6
NGS Frim3D reconstr.
Impact on LO or truth WFS, but truncation is ok
fine on gaussian and non gaussian sodium profiles
SEE MISKA et al. poster on that topic
WFS detectors & controllers
NIR SELEX detector GRAVITY
320x256 eAPD array
RON<3e @ 1k frames/s; 47Kelvin
Low order WFS for MAORY-LTAO
But also RAPID @ LETI
E2V + LAM Potential detector for SCAO?
240x240 pixels RON 0.2e @ 1.5kHz
E2V
840x840 pixels; 24-μ pixels
RON 3e @ 700 Hz frame/s
delivery Q4/2013-Q1/2014
1.6k x1.6k?
31
Pixel number
Detector technology
Pixel Pitch
Pixel topology
Sub-aperture
Array architecture
Pixel full well
Read noise including ADC
ADCs configuration
Frame rate
“Natural Guide Star Detector” NGSD - 880x840 pixels with
840x840 sensitive pixels
Thinned backside illuminated CMOS 0.18µm
24µm
4T pinned photodiode pixel
20x20 pixels
42x42 sub-apertures of 20x20 pixels
4000 e< 3.0 e-RMS
20 x 880 column ADCs, 9 (goal 10) bits
700 fps up to 1000 fps with degraded performance
32
Deformable mirror & RTC path finders
RTC
box
Co-processing
cluster
CILAS 1370 actuators piezo
DM with
4.5 mm pitch
LGS tomography with 4
LGS WFSs 40x40 @ 1
kHz
Single conjugate & Laser Tomography AO for HARMONI
 SCAO: Proposed as part of HARMONI, a complementary AO capability for highest performance
on “bright” targets: Solar system, High contrast science, GC…
 Wavefront sensor (optimized for high contrast, differential tracking capability, …)
 wavefront sensor: Visible or IR or both?
M4 adaptive mirror corrector (baseline fitting error 142 nm rms) ~50cm sampling on M1
 GLAO: Enhanced seeing capability using NGS wavefront sensors?: Earliest galaxies?
60”
 LTAO: High throughput, low emissivity, high sky coverage, “High” Sr performance required for
faint targets: QSOs, GRBs, High-z G, etc…
6 Laser Guide stars side launched 2’ diameter
2 IR Natural Guide Star corrected with μDM
Uses M4 adaptive mirror (baseline fitting error 142 nm rms)
High throughput & low emissivity
NGS
LGS
120”
4.2’
Trade-offs on number / position of LGSs
LTAO: 6LGS, 4 laser launch stations (LLS), TT stars close to center of FOV
500Hz, 500 iterations, 2 frames delay
Seeing 0.8’’, L0=25m, tau0~3ms
Importance of Cn2 profile assumptions for performance estimates M. Sarazin et al.
9 layers simulated, 9 layers reconstructed (unless otherwise noted)
Single conjugate and Laser Tomography AO for HARMONI
Semi-analytic simulations for 39m telescope, LGSs @ 1’ (radius), 6LGSs
40 atmospheric layers simulated, 7 reconstructed
PSF available for different wavelengths under request: 0.8, 1.0, 1.2, 1.6, 2.2, 10.0 um
 On-axis PSF
With and without telescope WFE (very preliminary error budget)
Seeing=0.67 @ 30 degrees
Contain some “reasonable” TT jitter (±3mas rms); pessimistic (TBC)? telescope wind-skake &
optimum control of low order modes critical
Sr(K) =54%
Sr(K) = 48.5 %
Without telescope WFE
With telescope WFE
Courtesy: Le Louarn-ONERA
LTAO performance (from Phase A 42 m)
NOMINAL CONDITION; Sseeing = 0.8; Zenith = 0°; θ0 = 2.08"
900
1250
1650
2200
3500
4800
10500
Width 10 mas
10,3
21,1
26,1
26,4
17,8
13,7
3,9
Width 20 mas
15,1
32,1
42,5
48,5
45,6
37
14,3
Width 40 mas
18,2
37,8
53,6
63,8
62,8
61
35,1
Width 60 mas
22,4
40,5
56,3
67,8
75,9
69,1
54,2
Width 80 mas
23,2
42,4
58,2
70,2
79,8
80,1
63,8
Width 100 mas
25,6
44,8
59,5
71,7
81,3
84,6
67,5
Strehl Ratio (%)
5,5
18,8
35,3
52,7
75,6
90,5
96,9
HARMONI / SIMPLE
FWHM (seeing limited) [mas]
646
609
586
546
483
442
357
METIS
FWHM (ATLAS)
[mas]
8,2
9
10,1
12,1
17,6
23,7
49,1
FWHM (Diffraction)
[mas]
4,4
6,1
8,1
10,8
17,2
23,6
49,6
lambda (nm)
Ensquared Energy (%)
Without telescope error budget to be
updated for 39 m
OPTIMOS / EAGLE like
ATLAS sky coverage
Perf
SC (pole)
52 % SR in K
92 %
40 % SR in K
96%
35 % SR in K
97%
13 % SR in K
100 %
Instrumentation arrangement optimization on
E-ELT Nasmyth platform
 Impact of telescope design change (4239m)
 Design optomechnical implementation of telescope metrology,
LTAO WFSing, and instrument pre-optics to ensure optimum
configuration
 Ensure good maintenance access on whole Nasmyth platform
 Progress on end-to-end Wavefront control strategy to ensure
completeness of metrology & AO sensor requirements
 Major work on-going!
On-going work for LTAO implementation at Nasmyth I
Option 3 – Gravity invariant cryostat
Big optics, but all static
From SCAO to LTAO for METIS
SCAO
 Excellent on-axis
 Integrated in METIS
 Minimize residual jitter
 ‘simple’ first light AO
LTAO
 Wide(r) field performance
 Accepts fainter GS(s)
 Increased sky coverage
 LGS configuration trade-off
on-going
SCAO for METIS
 SCAO internal to METIS
 Cold, low (M)IR background
 Dichroic first optic inside METIS
 Cold!
 Splits at ~2.5 micron
 Full METIS field ~18x18”
 Large field selector
 Full METIS field
 Allows or field de-rotation
Dichroic
ELT Focus
METIS Entrance Window
 ~40x40 sub-apertures
 IR WFS
 Embedded sources
 Selex experience Gravity
 Pyramid WFS
 Detector available
 But extended sources?
Field Selector
ADC?
Pupil de-rotator
2.2 µm
27 May
LTAO Simulations
2013
3.7 µm
10 µm
LTAO Simulations
AO Only
ESO Octopus Simulations/Miska Le Louarn
AO + Telescope Only
Next steps
 Preliminary design of M4 unit
 Consolidation of MAORY Project plan for next phases
 Pursue technology development for MAORY
 Optical design trade-off incl. 39 m update
 Update Nasmyth platform configuration: telescope metrology-
LTAO – HARMONI & METIS
 Update performance estimates/error budgets for the different
AO capabilities
 Consolidate interfaces with instruments
Conclusions
 An aggressive AO program is being developed for the VLT
 AO pathfinders for E-ELT are on-going @ VLT, WHT,…
 Major efforts & collaborations to bring key technologies to
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appropriate TRL
Facilitating AO community effort to address remaining key AO
fundamental issues (calibration, identification, control,
tomography, LGS & NGS WFSing, simulation….)
Preparing for construction of E-ELT AO capabilities
Setting up Consortium for the AO instrumentation
The main power of the E-ELT will reside in achieving, with the
help of AO, a spatial resolution never achieved at
optical/infrared wavelength to this depth before.
THANK YOU for your attention