WMKO Next Generation Adaptive OpticsWMKO Next Generation Adaptive OpticsScience Advisory Team:Science Advisory Team:

Introductions & NSAT ChargeIntroductions & NSAT Charge

Taft Armandroff, Mike Bolte, Taft Armandroff, Mike Bolte,

Shri Kulkarni, Hilton LewisShri Kulkarni, Hilton Lewis

June 11, 2009June 11, 2009

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Introductions

• NSAT Members:– Laird Close – George Djorgovski– Richard Ellis– James Graham– Michael Liu– Keith Matthews– Mark Morris (chair)– Tomasso Treu

• Directors• NGAO Team

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Keck AO Science Product217 refereed science papers (thru May/09)

29%52%19%

M. Liu

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Area Sub-TopicNumber of

PapersBrown dwarfs & low mass stars 15

Galactic Center 10Compact objects 2

Star formation 1High redshift galaxies 11Gravitational lensing 5Stellar populations 3

Supernovae 5Kuiper Belt 4Asteroids 1

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Keck AO Science Capabilities

Keck AO First TAC-allocated Science Milestones

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NGAO Project Milestones & Funding

• All of the following successfully completed:– Jun/06. Proposal submitted– Apr/08. System Design Review– Nov/08. TMT AO cost comparison– Mar/09. Build-to-cost concept review

• Preliminary Design Review planned for Apr/10

• TSIP provided $2M for the preliminary design• ATI (Nov/08) & MRI (Jan/09) proposals submitted for

NGAO related activities• Private funding being sought• MRI-R2 & TSIP proposals will be submitted this year

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NGAO System Design Review (April/08)

Very Experienced Review Committee:• Brent Ellerbroek & Gary Sanders (TMT)• Bob Fugate (NMT) & Norbert Hubin (ESO)• Andrea Ghez (UCLA) & Nick Scoville (Caltech)

• “The review panel believes that Keck Observatory has assembled an NGAO team with the necessary past experience … needed to develop the NGAO facility for Keck. It is a sound, though aggressive, strategy to be among the first observatories to develop and depend on advanced LGS AO systems as a means to maintain Keck’s leadership in ground-based observational astronomy for the immediate future.“

• “The panel also believes that NGAO is an important pathfinder for the 2nd generation of AO based instruments for future ELT’s”

• “The NGAO Science cases are mature, well developed and provide high confidence that the science … will be unique within the current landscape.”

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NGAO Build-to-Cost Review (March/09)

Very Experienced Review Committee:• Brent Ellerbroek (TMT)• Michael Liu (U. Hawaii)• Jerry Nelson (TMT, UCSC)

• Cost cap with instruments & contingency: $60M then-year dollars• "The Committee strongly congratulates the NGAO team for a concise,

convincing presentation which demonstrates that the above criteria for further development of the system have been very effectively met. We recommend that the project is now ready to proceed with the Preliminary Design Phase to continue the development of the updated system concept, with no further changes in overall scope or basic architecture either necessary or desirable."

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NSAT Charter

• The purpose of the NSAT is to help ensure that the NGAO facility will provide the maximum possible science return for the investment and that NGAO will meet the scientific needs of the Keck community.

• To that end the NSAT will provide science advice to the NGAO project with an emphasis on the further development of the science cases and science requirements.

• The NSAT is also expected to provide science input in such areas as performance requirements, operations design, and design trades.

• The NSAT will report to the Directors, providing a panel of experts for them to consult, and will work closely with the NGAO Project Scientist providing an expert science team that represents a wide range of AO interests in the Keck community.

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NSAT Responsibilitiesfor the Preliminary Design

Collaborate with the NGAO project scientist and project team to:• Further develop the NGAO science cases and science case requirements.

• Evaluate the scientific performance of the NGAO design on various science cases (for example, PSFs reflecting the modeled NGAO performance may be provided for evaluation).

• Determine what science cases and requirements should drive a phased implementation of NGAO and the scientific impact of a phase implementation.

• Support funding efforts by contributing to the science portion of proposals and/or making presentations.

• Determine optimal observing and operations strategies including further development of science case observing scenarios and providing input to the Operations Concept Document and the design of the observing tools.

• Ensure that NGAO is scientifically competitive by providing input on NGAO’s science competitiveness and complementarity with respect to other facilities.

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NSAT Responsibilitiesfor the Preliminary Design

Collaborate with the NGAO project scientist and project team to:• Ensure that the broader Keck community’s input is taken into account in the

development of the NGAO Preliminary Design by liaising with the broader community.

• Promote NGAO in the Keck, national and international communities.

• Ensure that technical (e.g., design and performance) trades made by the NGAO project have adequate science input by evaluating the science impact of proposed changes.

• Prepare and present the NGAO science issues and broader perspective to the Directors and SSC.

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NSAT Longer Term Role

• The NSAT role and responsibilities in the remaining phases of the NGAO project will be assessed towards the end of the Preliminary Design phase. The Directors will seek input from the NSAT and NGAO project in defining the NSAT’s longer term role.

WMKO Next Generation Adaptive WMKO Next Generation Adaptive Optics Introduction for the NSATOptics Introduction for the NSAT

Peter Wizinowich, Sean Adkins, Rich Dekany, Peter Wizinowich, Sean Adkins, Rich Dekany, Don Gavel, Claire Max, Elizabeth McGrath Don Gavel, Claire Max, Elizabeth McGrath

& the NGAO Team& the NGAO Team

June 11, 2009June 11, 2009

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Presentation Sequence

• Brief Overview• Science Priorities• Design & Performance• Science Instruments• How can the NSAT help?

OverviewOverview

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NGAO - Next Generation AO

Key New Science Capabilities

Near Diffraction-Limited in Near-IR (K-Strehl ~80%)

AO correction at Red Wavelengths (0.65-1.0 m)

Increased Sky Coverage

Improved Angular Resolution, Sensitivity and Contrast

Improved Photometric and Astrometric Accuracy

Imaging and Integral Field Spectroscopy

Key Science Goals

Understanding the Formation and Evolution of Today’s Galaxies

Measuring Dark Matter in our Galaxy and Beyond

Testing the Theory of General Relativity in the Galactic Center

Understanding the Formation of Planetary Systems around Nearby Stars

Exploring the Origins of Our Solar System

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How is NGAO different from Keck’s AO today?

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NGAO System Architecture

Key Features:1. Fixed narrow field laser tomography2. AO corrected NIR TT sensors3. Cooled AO enclosure smaller4. Cascaded relay5. Combined imager/IFU instrument

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Project Milestones

Year Month NGAO Project Milestone2006 June NGAO Proposal to SSC - complete2006 Oct. System Design Start - complete2008 April System Design Review - complete2009 March Build-to-Cost Review - complete2009 Dec. Laser Preliminary Design Reviews2010 April Preliminary Design Review2011 April Laser Final Design Review2011 Sept. Keck II Center Launch Telescope Operational2012 April Detailed Design Review2013 Oct. Pre-Lab I&T Readiness Review2013 April Pre-Ship Readiness Review2014 July NGS AO First Light2014 Sept. LGS AO First Light2014 Oct. 15A Shared-Risk Science Availability Review2015 Feb. Operational Readiness Review

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Cost Estimate in Then-Year $k

In FY09 $: $42M for NGAO, $12M for Instrument(s) $54M total

NGAO Instrument(s) FY07 FY08 FY09 FY10 FY11 FY12 FY13 FY14 FY15 TotalIFS Design 51 229 78 358Imager and IFS Instrument 123 443 4284 4264 486 12 9613Contingency (10/30%) 17 67 1309 1279 146 4 2822

NGAO Instrument Total = 192 739 5670 5544 632 15 0 12793

Overall Total = 739 709 1432 4697 11670 15678 12361 10161 2436 59883

NGAO System FY07 FY08 FY09 FY10 FY11 FY12 FY13 FY14 FY15 TotalSystem Design 739 495 1234Preliminary Design 214 1240 1492 2946Detailed Design 1600 5500 978 8078Full Scale Development 400 500 7415 8715 5262 22293Delivery & Commissioning 1764 1825 3589Contingency (24%) 466 1741 3014 3119 611 8951

NGAO Total = 739 709 1240 3958 6000 10134 11729 10145 2436 47090

Actuals ($k) Plan (Then-Year $k)

Science PrioritiesScience Priorities

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We categorized science cases into 2 classesWe categorized science cases into 2 classes

1.1. Key Science Drivers:Key Science Drivers:

– These push the limits of AO system, instrument, and telescope performance. Determine the most difficult performance requirements.

2.2. Science Drivers:Science Drivers:

– These are less technically demanding but still place important requirements on available observing modes, instruments, and PSF knowledge.

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““Key Science Drivers” Key Science Drivers” (in inverse order of distance)(in inverse order of distance)

1.1. High-redshift galaxiesHigh-redshift galaxies

2.2. Black hole masses in nearby AGNsBlack hole masses in nearby AGNs

3.3. General Relativity at the Galactic CenterGeneral Relativity at the Galactic Center

4.4. Planets around low-mass starsPlanets around low-mass stars

5.5. Asteroid companionsAsteroid companions

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1.1. Gravitationally lensed galaxiesGravitationally lensed galaxies

2.2. QSO host galaxiesQSO host galaxies

3.3. Resolved stellar populations in crowded fieldsResolved stellar populations in crowded fields

4.4. Astrometry science (variety of cases)Astrometry science (variety of cases)

5.5. Debris Disks and Young Stellar ObjectsDebris Disks and Young Stellar Objects

6.6. Giant Planets and their moonsGiant Planets and their moons

7.7. Asteroid size, shape, compositionAsteroid size, shape, composition

““Science Drivers” Science Drivers” (in inverse order of distance)(in inverse order of distance)

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Key Science Requirements:1. Assembly and star formation history of high z galaxies

• “High Redshift Galaxies” has very wide scope– z > 6: Finding and characterizing galaxies

– 3 < z < 6: Morphologies, colors

– 1 < z < 3: Internal kinematics, structure at time of peak star formation and merging

• To define “Key Science Driver” we focused on 1 < z < 3– 1 < z < 3 epoch: spatial resolution of

10-m telescope has strong impact

• Prominent emission lines redshifted to J, H, K bands

• Sufficient signal-to-noise to spatially resolve internal kinematics, star formation rates, metallicity gradients using spatially resolved spectroscopy

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Cooled AO system for better performance at K-band

• Target goal: AO to contribute at most 30% (sky + tel) background

• This opens “typical” z~2.6 galaxies within reasonable observing times ~ 3 hours

• We have to assess how much it’s worth investing to cool NGAO at K band, in view of JWST’s great advantage in sensitivity

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Key Science Requirements:2. Black hole masses in nearby galaxies

• M- relation: black hole mass closely correlated with velocity dispersion of stars

• Spatial resolution: need to resolve the black hole's dynamical sphere of influence r

g = GM

BH/2

• If you see the Keplerian rise in the rotation curve, mass determination becomes more accurate

Simulation: 108 Msun BH at 20 Mpc, inclination 60 deg to line of sight

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Addition of optical bands:Addition of optical bands:advantage for BH mass determinationadvantage for BH mass determination

• With NGAO, diffraction-limited PSF core at Ca II triplet is major improvement in spatial resolution

– Enables many more low-mass black holes to be detected

– Better for resolving rg in nearby

galaxies, leading to more accurate measurements

– NGAO I-band can study high-mass distant galaxies to pin down extreme end of M- relation Minimum BH mass detectable vs.

distance, assuming local M- relation and 2 resolution

elements across rg

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Key Science Requirements:3. General relativistic effects in the Galactic Center

• Measure General Relativistic prograde precession of stellar orbits in Galactic Center

• Requires astrometric precision of 100 as (now 170 as) and radial velocity precision to 10 km/sec (now 17 km/sec)

Need to evaluate optimal spectral resolution

Credit: UCLA Galactic Center Group

• Imaging field 10 x 10 arc sec• Near IR IFU spectra, R ≥ 4000, FOV ≥ 1” x 1”, need

IR ADC

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Galactic Center: possibility of detecting Galactic Center: possibility of detecting general relativistic effects near black holegeneral relativistic effects near black hole

• Use orbits of star(s) that pass very close to black hole

• Example: general relativistic precession

• SNR > 10 requires astrometric precision better than 0.1 mas

• Current astrometric precision of 170 as is only achieved for bright stars like S0-2.

Assumes radial velocity measurement errors of 10 km/s

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Key Science Requirements:4. Planetary & brown dwarf companions to low mass stars

• Faintness of low-mass stars, brown dwarfs, and the youngest stars make them excellent NGAO targets

• Small imaging field ≤ 5 arc sec• Relative photometry to 5%, astrometry to

PSF FWHM/10, contrast H = 13 at 1”• Instruments:

– Imaging 0.9 - 2.4 microns

– Single near IR IFU spectroscopy, still need to specify spectral resolution

• Observing modes: coronagraph needed

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Contrast Requirements for Planets Around Low-Mass Stars

• Need to reach at least H=10 at 0.2” for our primary target sample (planets around nearby old field brown dwarfs).

• We plan to simulate achievable contrast ratio using reasonable coronagraph +

NGAO PSF models• Preliminary simulations from SDRindicate a simple coronagraph with a 6/D spot size may be sufficient for most science cases.

Brown dwarf 1/30 mass of Sun (hidden behind occulting mask)

Giant planet (2x mass of Jupiter)

Simulations by Bruce Macintosh and Chris Neyman

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Key science requirements: 5. Multiplicity, size, shape of minor planets

• Minor planet formation history and interiors by accurate measurements of size, shape, companions

• Small, on-axis imaging field ( ≤ 3 arc sec)• Relative photometry to 5%, astrometry ≤ 5

mas, wavefront error ≤ 170 nm, contrast H 5.5 at 0.5 arc sec

• Instruments: – Imaging: visible and near-IR– Near IR IFU spectroscopy: 1.5 arc sec field;

still need to specify spectral resolution

• Observing modes: non-sidereal tracking, <10 minute overhead switching between targets

Asteroid Sylvia and moons

Nix and Hydra

Credit: D. Tholen

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Science Requirements &

Performance Budget Process

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Science Priority Input: SDR Report• “The NGAO Science cases are mature, well developed and provide enough

confidence that the science … will be unique within the current landscape.”

• “The science requirements are comprehensive, and sufficiently analyzed to properly flow-down technical requirements.”

• “… high Strehl ratio (or high Ensquared Energy), high sky coverage, moderate multiplex gain, PSF stability accuracy and PSF knowledge accuracy … These design drivers are well justified by the key science cases which themselves fit well into the scientific landscape.”

• The panel was concerned about complexity & especially the deployable IFS

– “However, the review panel believes that the actual cost/complexity to science benefits of the required IFS multiplex factor of 6 should be reassessed.”

– “… recommends that the NGAO team reassess the concept choices with a goal to reduce the complexity and risk of NGAO while keeping the science objectives.”

• The panel had input on the priorities

– “The predicted Sky Coverage for NGAO is essential and should remain a top requirement.”

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Science Priority Input: Keck Scientific Strategic Plan

• “NGAO was the unanimous highest priority of the Planetary, Galactic, & Extragalactic (high angular resolution) science groups.

• “NGAO will reinvent Keck and place us decisively in the lead in high-resolution astronomy. However, the timely design, fabrication & deployment of NGAO are essential to maximize the scientific opportunity.”

• “Given the cost and complexity of the multi-object deployable IFU instrument for NGAO, …, the multi-IFU instrument should be the lowest priority part of the NGAO plan.”

• Planetary recommendations in priority order: higher contrast near-IR imaging, extension to optical, large sky coverage.

• Galactic recommendations in priority order: higher Strehl, wider field, more uniform Strehl, astrometric capability, wide field IFU, optical AO

• Extragalactic high angular resolution recommendations: a balance between the highest possible angular resolution (high priority) & high sensitivity

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Science Implications of no Multiplexed d-IFU

• As a result of our Build-to-Cost approach, we have eliminated the multiplexed d-IFU.– Reduces complexity and decreases risk of overall NGAO system

– Available laser power can be utilized to provide excellent performance for science targets over narrow fields (<40”)

Science implications:• Galaxy Assembly and Star Formation History

– Reduced observing efficiency (from 6x to 1x)

– Slightly increased performance for single, on-axis target

– Decreased overall statistics for understanding galaxy evolution. We will need to carefully select sub-categories of high-z galaxies to focus on.

• General Relativity in the Galactic Center– Decreased efficiency in radial velocity measurements (fewer stars

observed simultaneously)

– Can gain back some of this with a single IFU with a larger FOV.

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Flowdown of Science Priorities(resultant NGAO Perspective)

Based on the SDR science cases, SDR panel report & Keck Strategic Plan:1. High Strehl

• Required directly, plus to achieve high contrast NIR imaging, shorter AO, highest possible angular resolution, high throughput NIR IFU & high SNR

• Required for AGN, GC, exoplanet & minor planet key science cases

2. NIR Imager with low wavefront error, high sensitivity, ≥ 20” FOV & simple coronagraph• Required for all key science cases.

3. Large sky coverage• Priority for all key science cases.

4. NIR IFU with high angular resolution, high sensitivity & larger format• Required for galaxy assembly, AGN, GC & minor planet key science cases

5. Visible imaging capability to ~ 800 nm• Required for higher angular resolution science

6. Visible IFU capability to ~ 800 nm7. Visible imager & IFU to shorter 8. Deployable multi-IFS instrument (removed from plan)

– Ranked as low priority by Keck SSP 2008 & represents a significant cost

IncludedExcluded

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Performance vs Science RequirementsKey Science Driver SCRD Requirement Performance of B2C

Galaxy Assembly(JHK bands)

EE 50% in 70 mas for sky cov = 30% (JHK)

EE > 70% in 70 mas for sky cov 90% (K band)

Nearby AGNs(Z band for Ca triplet)

EE 50% in 1/2 grav sphere of influence

EE 25% in 33 mas MBH 107 Msun @ Virgo cluster (17.6 Mpc )

General Relativity at the Galactic Center(K band)

100 as astrometric accuracy 5” from GC

Need to quantify. Already very close to meeting this requirement with KII AO.

Extrasolar planets around old field brown dwarfs (H band)

Contrast ratio H > 10 at 0.2” from H=14 star (2 MJ at 4 AU, d* = 20 pc)

Meets requirements (determined by static errors)

Multiplicity of minor planets (Z or J bands)

Contrast ratio J > 5.5 at 0.5” from J < 16 asteroid

Meets requirements: WFE = 170 nm is sufficient

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How does NGAO fit into How does NGAO fit into the competitive landscapethe competitive landscape

• Other ground-based observatories

• JWST & ALMA

• TMT

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NGAO in the world of 8-10 m telescopes: NGAO in the world of 8-10 m telescopes: Uniqueness is high spatial resolution, shorter Uniqueness is high spatial resolution, shorter ’s, AO-fed NIR IFS’s, AO-fed NIR IFS

• Most 8-10 m telescopes plan either high contrast or wide field AO

• Only VLT has narrow-field mode, but has low sky coverage and needs best seeing

Type Telescope GSNext-Generation AO Systems

for 8 to 10 m telescopesCapabilities Dates

High-contrast Subaru N/LGS Coronagraphic Imager Hi(CIAO)Good Strehl, 188-act curvature,

4W laser2008

High-contrast VLT NGS Sphere (VLT-Planet Finder) High Strehl 2010

High-contrast Gemini-S NGS Gemini Planet Imager (GPI) Very high Strehl 2010

Wide-field Gemini-S 5 LGS MCAO 2Õ FOV 2009

Wide-field Gemini 4 LGS GLAO Feasibility Study Completed ?

Wide-field VLT 4 LGSHAWK-I (near IR imager) +

GRAAL GLAO7.5' FOV, AO seeing reducer,

2 x EE in 0.1''2012

Wide-field VLT 4 LGSMUSE (24 vis. IFUs) +

GALACSI GLAO1' FOV; 2 x EE in 0.2" at 750nm 2012

Narrow-field VLT 4 LGSMUSE (24 vis. IFUs) +

GALACSI GLAO7.5Ó FOV, 10% Strehl @ 750 nm in best seeing, low sky coverage

2012

Table 1. Next-Generation AO Systems Under Development for 8 - 10 meter Telescopes

42

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Competitive Landscape: ALMACompetitive Landscape: ALMA

• Millimeter and sub-millimeter wavelengths (0.35 - 9 mm)

• Typical spatial resolutions ~ 0.1”

• Resolutions for widest arrays as low as 0.004” at the highest frequencies

• ALMA science: regions colder and more dense than those seen in the visible and near-IR by NGAO

• Keck NGAO and ALMA observations complementary for:– Spatially resolved galaxy

kinematics, z < 3

– Debris disks and young stellar objects

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NGAO comparison to JWST & TMTWMKO NGAO JWST

Diffraction-limit (mas) at 2 m 41 63Diffraction-limit (mas) at 1 m 20 limited by samplingSensitivity 1x ~200x at 2 mImager NGAO Imager NIRCam IRIS Imager IRMS

Detector H4RG 4x H2RG H4RG H2RGWavelength range ( m) 0.8-2.4 0.6-2.35 0.8-2.5 0.8-2.5Sampling (mas/pixel) 8.5 31.7 4 60FOV (arcsec) 35 130 15 120

Spectrometer NGAO IFS NIRSpec IRIS IFS IRMSDetector H4RG 2x H2RG H4RG H2RGWavelength range ( m) 0.8-2.4 0.6-2.35 0.8-2.5 0.8-2.5

Spectral Resolution R~4000

R~100 & ~1000 multi-object modesR~3000 IFU or long-

slit modes

Two image slicers; R~4000

R=3270 (0.24" slit)R=4660

(0.16" slit)Spatial Resolution (mas) 10, ~25 & ~60 ~100 4 to 50 160

FOV (arcsec) 0.8, 2 & 4200 FOR

4 slit; 3x3 IFU up to 3 120 FORProjected 1st science paper ~2015 ~2014

TMT NFIRAOS147

~2020

~80x

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NGAO comparison to JWST

Key Science Case JWST & NGAO

Galaxy Assembly (JHK)

JWST much more sensitive at K.NGAO sensitivity higher between OH lines at H.NGAO sensitivity higher for imaging & spectroscopy at J.NGAO wins in spatial resolution at all .NGAO provides higher spectral resolution.

Nearby AGNs (Z) Only NGAO provides needed spatial resolution (especially at Ca triplet).

General Relativity at Galactic Center (K)

Only NGAO provides needed spatial resolution (especially important to reduce confusion limit).Long term monitoring may be inappropriate for JWST.

Extrasolar Planets around old Field Brown Dwarfs (H)

Only NGAO provides needed spatial resolution.JWST coronagraph optimized for 3-5 m, >1"; NGAO competitive ² 2 m, <1".

Multiplicity of Minor Planets (Z or J) Only NGAO provides needed spatial resolution.

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NGAO comparison to TMT• NGAO & NFIRAOS wavefront errors are similar (162 vs 174 nm rms).

– Similar Strehls. TMT will have higher spatial resolution and sensitivity.– NGAO advantages: earlier science, accumulate experience that TMT will benefit from. NGAO will screen

most important targets for TMT (time scarce), do synoptic obsns.

Key Science Case TMT & NGAO

Galaxy Assembly (JHK)

TMT IRIS lenslets (0.004″/px, 0.009″/px) have outstanding spatial resolution. TMT IRIS slicer (0.025"/px, 0.05"/px) gives same spatial resolution as NGAO IFU. TMT has higher sensitivity. NGAO may do many Z < 3 targets before TMT.

Nearby AGNs (Z)

NGAO will screen most important targets for TMT. With 3x higher spatial resolution TMT will detect smaller nearby black holes, and more distant large black holes. NGAO IFU: good performance at 850nm Ca triplet is specific requirement. Could potentially go to shorter wavelengths (e.g. Ha).

General Relativity at Galactic Center (K)

TMT wins in spatial resolution, sensitivity less important (confusion limited). Significant value in continuing NGAO astrometry into TMT era (MCAO field stability concern; Keck access easier). NGAO synoptic advantage.

Extrasolar Planets around old Field Brown Dwarfs (H)

TMT spatial resolution an advantage.Control of static wavefront errors & PSF characterization will be critical (NGAO will have 5 year head start on experience which TMT can learn from).NGAO synoptic advantage.

Multiplicity of Minor Planets (Z or J)

TMT spatial resolution an advantage but NGAO could move to shorter . A lot of this science could be done by NGAO before TMT.NGAO synoptic advantage.

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Science Team Tasks During PD Phase

• Ensure that the NGAO science cases fulfill our goals of keeping Keck uniquely powerful and competitive by producing outstanding science.

• Expand upon goals of “Science Drivers”, and finish documenting the AO performance requirements necessary to achieve these goals.

– Iterative with AO Systems Engineering group

• Detailed science simulations of “Key Science Drivers” to assess the required level of PSF accuracy, stability, uniformity, and knowledge as a function of position and time. Collaboration with IRIS team. Implications for:

– achievable astrometric and photometric accuracy

– achievable contrast ratio

– morphological and spectroscopic studies

• Incorporate instrument design characteristics as these develop

• Develop detailed observing scenarios for each “Key Science Driver” to define pre- and post-observing tools and observing sequences.

47

Community Input to Science Team Efforts

• Continued discussions with Keck community to ensure that science case requirements remain consistent and up-to-date with advancing discoveries, changing methodology, modifications to the current AO system design, and maturing instrument concepts.

• Input from observers to improve planning tools, observing practices, support, and efficiency.

• Feedback regarding NGAO science opportunities that complement other ground-based AO and space-based facilities, and that take advantage of the uniqueness space provided by NGAO at Keck.

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A Key Issue: A Key Issue: What are the requirements for What are the requirements for PSF stability and knowledge?PSF stability and knowledge?

• In System Design phase, we stated requirements in terms of photometric and astrometric accuracy

– Develop error budgets

• These in turn need to flow down to specific levels of PSF stability, uniformity, and knowledge

– “Stability” refers to temporal uniformity

– “Uniformity” refers to spatial uniformity (specify over what field)

– “Knowledge” -- no matter what the actual stability and uniformity, how well do you know the PSF that pertained during a specific science exposure?

• Develop a set of quantitative measures of “PSF Knowledge”

– Different science cases are sensitive to different aspects of the PSF

– Examples: total energy in core, details of halo, FWHM of core, etc

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Science Operations Design• Complexity of NGAO requires that we have a good science operations

plan and supporting software.• We are developing an Observing Operations Concept Document

(OOCD) to detail observing process for each science case• Science operations design optimizes observing efficiency:

(e.g., >80% open shutter time for high-z galaxies)– Pre-observing tools: selection of guide stars, performance and SNR

prediction, planning and saving the observation sequences. – Operations tools integrating NGAO, telescope and instruments, allowing for

parallel command and multi-system coordination.– Dithering/offsetting/centering using internal steering optics, that do not

require opening/closing AO loops and offsetting the telescope.

• Quality of the final data product:– Use of WFC and ancillary data for monitoring atmospheric conditions and

image quality (SR, EE, photometry, etc).– Data archiving for calibration and science products. – PSF calibration, including PSF reconstruction from telemetry.– Post-processing software for IFU data.

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Pre-observing toolsGUIs and high-level operations tools

Multi-system Command Sequencer

Subsystem Command Sequencer

Science Operations Design

NGAO Design and PerformanceNGAO Design and Performance

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NGAO System Architecture

Key Features:1. Fixed narrow field laser tomography2. AO corrected NIR TT sensors3. Cooled AO enclosure smaller4. Cascaded relay5. Combined imager/IFU instrument

5353

Strehl Ratio versus Laser Power

50W in science asterism

Science Strehl vs. Laser Power in Science Asterismfor 10” radius 3+1 “Tetrad” Asterism

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ergy

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EE70mas and Tip-Tilt Error vs. % Sky Coveragefor Galaxy Assembly case, median seeing

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EE70mas and Tip-Tilt Error vs. % Sky Coveragefor Nearby AGN case, median seeing

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Strehl Ratio and Tip-Tilt Error vs. % Sky Coverage for Exoplanets case, median seeing

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Strehl Ratio and Tip-Tilt Error vs. % Sky Coverage for Minor Planets case, median seeing

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Galaxy Assembly Performance vs. Sky Coverage

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% EE (70 mas)

K-bandb = 30

% EE (41 mas)

Complete sky coverage for IFS galaxy assembly science

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EE70mas and Tip-Tilt Error vs. % Sky Coveragefor Galaxy Assembly case, median seeing

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EE70mas and Tip-Tilt Error vs. % Sky Coveragefor Nearby AGN case, median seeing

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Performance versus Seeing

Median

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High Strehl for a wide range of seeing

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ehl R

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e re

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Science Strehl vs. Seeing Parameterfor 10” radius 3+1 “Tetrad” Asterism

r0 (meters)

5757

Off-axis Performance

Median seeing

Max. IFU radius

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Imaging radius requirement

Per

form

ance

Field Performance for Galactic Center

Off-axis Distance [arcsec]

58

Relative Positional Error

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+ Center Projection

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g) Current K2 LGS AO

+ Center Projection

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K2 Center Launch + New LaserMRI proposals - Predicted Performance for T Dwarf

Binary Case

Factor of 2x improvement 6x in dynamical mass determination

R = 16.2 NGS 31” off-axis50 zenith angle

1% photometry

Science InstrumentsScience Instruments

60

Background

• NGAO science requirements established a need for certain capabilities in the SD phase– Imaging

• ~700 nm to 2.4 µm

• high contrast coronagraph

– Integral field spectroscopy in near-IR and visible• spatially resolved spectroscopy for kinematics and radial velocities

• high sensitivity

• high angular resolution spatial sampling

• R ~ 3000 to 5000 (as required for OH suppression and key diagnostic lines)

• Improved efficiency– larger FOV– multi-object capability

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Constraints & Opportunities

• Constraints– Cost

• Need to provide capability within a limited amount of funding

• Must understand which requirements drive cost

– Complexity• Must resist the temptation to add features

• Maximize heritage from previous instruments

• Opportunities– NGAO offers extended wavelength coverage

• Significant performance below 1 µm, Strehl ~20% at 800 nm

• Substrate removed HgCdTe detectors work well below 1 µm

– Exploit redundancies in compatible platforms – e.g. Near-IR imager and Near-IR IFS

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Wavelength Coverage

• CCD vs. IR FPA– Substrate removed HgCdTe detectors work well below 1 µm

– ~20% lower QE than a thick substrate CCD

– Non-destructive readout takes care of higher read noise of IR array

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Wavelength, m

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ns

mis

sio

n, %

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NGAO visible

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K Y J H

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LBNL QE H2RG QE

Teledyne min. spec. for substrate removed H2RG

63

NGAO Imaging Capability• Broadband

– z, Y, J, H, K (0.818 to 2.4 µm)– photometric filters for each band plus narrowband filters similar to NIRC2

• Plate scale– 1 or more plate scales selected to optimally sample the diffraction limit, e.g.

(/2D), 8.4 mas at 0.818 µm– Finer sampling may be important for photometry, astrometry– Science requirement for ≥ 20" diameter FOV

– Multiple plate scales increase cost and may limit performance

• Simple coronagraph

• Throughput ≥ 60% over full wavelength range

• Sky background limited performance

Sampling /2D(mas) /3D(mas)

Pixel scale 8.4 5.6Detector size

2048 x 2048 (H2RG) 17.3 11.54096 x 4096 (H4RG) 34.6 23.0

@z band cut-off (0.818 m)

FOV (")

64

NGAO IFS Capability• Narrowband

– z, Y, J, H, K (0.818 to 2.4 µm)– ~5% band pass per filter, number as required to cover each wave band

• Spectroscopy– R ~4,000– High efficiency e.g. multiple gratings working in a single order

• Spatial sampling (3 scales maximum)• 10 mas e.g. (/2D) at 1 µm • 50 to 75 mas, selected to match 50% ensquared energy of NGAO• Intermediate scale (20 or 35 mas) to balance FOV/sensitivity trade off

• FOV on axis– 4" x 4" at 50 mas sampling– possible rectangular FOV (1" x 3") at a smaller spatial sampling

• Throughput ≥ 40% over full wavelength range• Detector limited performance

65

Narrowband Science

• Extra-galactic– IFS will be used for targets with known redshifts

• Therefore 5% bandpass sufficient?• 5% spans Hα and NII lines for example

– 4 narrowband (5%) filters will cover the K-band

– Excitation temperatures• Need at least 4 lines• Can expect to get 2 or more in each filter• Can optimize center wavelength to maximize this• Practical to use 2 or more exposures to get enough lines

– Imaging spectrograph allows you to detect, and discount image motion for better photometric matching of spectra

– Need to have enough FOV to ensure you cover the whole object in each exposure

• Exoplanet detection– Broadband filters available with narrow FOV ~1" x 1"

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Narrowband Science• Nearby AGN (Black Holes)

– Galaxy kinematics• CO bandhead 4 to 5% wide (OSIRIS Kn5 filter)• Brackett gamma, H_2 emission lines (OSIRIS Kn3 filter)

– Remain in that passband to z = 0.03

• Same arguments on practicality of non-simultaneous spectra apply

– Central Black Hole• Narrowband adequate for measuring black hole mass (only 1 line) • ~1“ diameter FOV

• Galactic Center (e.g. GR effects)– Narrowband acceptable for RV measurements– Being used now– Want better SNR

• Throughput• Higher angular resolution to reduce stellar confusion, but keep present FOVs

– Could use more FOV

67

Where can the NSAT best contribute?Where can the NSAT best contribute?NGAO Team SuggestionsNGAO Team Suggestions

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Potential NSAT Contributions: based on the Charter

• The purpose of the SAT is to help ensure that the NGAO facility will provide the maximum possible science return for the investment, and that NGAO will meet the scientific needs of the Keck community. 

• To that end the SAT will provide science advice to the NGAO project, with an emphasis on the further development of the science cases and science requirements.  For example:

– Advice on overall science priorities

– Ensuring that NGAO will play a long term vital role in the era of TMT, JWST, etc.

– Advice when there are design trades to be made (science benefit vs. added cost or complexity; priorities between the various science cases)

– Advice on the science instrument concept and requirements

• Seeking community input & informing the community about NGAO developments

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Potential NSAT Contributions

• We seek your help in the following near-term areas:– Strengthening the science cases & the definition of the science

requirements for NGAO & the NGAO science instruments Science Case Requirements Document (KAON 455)• Ex., science case for optical wavelengths

– Provide guidance on the Observing Operations Concepts to ensure they meet the scientific needs of the users Observing Operations Concept Document (KAON 636)

– Understanding what factors limit science performance (astrometry, photometry, contrast, sensitivity, observing efficiency, PSF knowledge, etc.)

– Participating in the development of the science instrument requirements and concept

– Science input to proposals (Federal & private; MRI-R2 by Aug. 10)

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Some areas in which we could use help from students or postdocs

In many cases the underlying work could be done by grad students or postdocs (would like your help in engaging students & postdocs):

• Further develop the science cases for optical wavelengths– Science benefit, if any, of working at shorter but lower Strehl (e.g. Ha)

• How stable and well-known does the PSF have to be, for the various science cases

– AGNs and quasars, planets around low-mass stars, astrometry applications

• Science simulations in support of the IFU design– Trades between high spatial resolution and high sensitivity, for specific scenarios

• Astrometry error budget for the Galactic Center– Which aspects are understood today– Of the ones not yet understood, which are most important to tackle 1st

• Resolved stellar populations science case needs to be quantified– Start by choosing 1 or 2 specific science scenarios that make sense given

NGAO’s high Strehl but small field of view

• Several specific issues involving strategies for high contrast imaging

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How would you like to help?

• Are there areas that you think we missed?• What additional information do you need?• What can we sign you up for?