Next Generation Adaptive Optics (NGAO)
System Design Phase Update
Peter Wizinowich, Rich Dekany, Don Gavel, Claire Max
Science Case Presenters: Brian Cameron, David Law, Jessica Lu,
Phil Marshall, Chuck Steidel, Tommaso Treu
Technical Team: Sean Adkins, Brian Bauman, Jim Bell,
Antonin Bouchez, Matthew Britton, Jason Chin, Ralf Flicker,
Erik Johansson, David Le Mignant, Chris Lockwood, Liz McGrath,
Anna Moore, Chris Neyman, Viswa Velur
Keck Strategic Planning Meeting
September 20, 2007
Presentation Sequence
1:00 pm WMKO Strategic Plan & NGAO (Wizinowich)
1:10 pm NGAO System Design Phase Status
1:15 pm Science Cases & Requirements
– Overview (Max)
– Precision astrometry at the Galactic Center & in sparse fields
(Cameron & Lu)
– High redshift galaxies with multiple IFU’s (Steidel & Law)
– Gravitationally lensed galaxies with single IFU’s (Marshall & Treu)
2:20 pm System Architecture (Dekany)
2:30 pm Discussion
– Potential Topics
3:00 pm Done
2
WMKO Strategic Plan & NGAO
Keck Strategic Plan:
Twenty-year strategic goals
•
•
•
•
Leadership in high angular resolution astronomy
Leadership in state of the art instrumentation
Highly efficient observing
Complementarity with ELTs
• NGAO supports all of these!
4
Keck AO Strategic Plan: NGAO
• AO strategic plan established by Keck AO Working
Group in Nov/02 & reaffirmed in Sept/04:
“AOWG vision is that high Strehl, single-object, AO
will be the most important competitive point for Keck
AO in the next decade.”
• Sept/05: New AOWG tasked by Observatory & SSC
to develop science case for Keck NGAO.
• Jun/06. NGAO proposal approved.
Multi-object also emphasized
5
Keck AO Science Productivity
Refereed Keck AO Science Papers by Year & Type
20.0
18.0
Number of
16.0
126 NGS & 30 LGS
Solar System
Galactic
Extra-galactic
14.0
12.0
10.0
8.0
6.0
4.0
Substellar binaries
2.0
0.0
2000
2001
2002
2003
2004
2005
2006
2007
Year
6
Key new capabilities for NGAO
1. Dramatically improved near-IR performance
•
•
•
Significantly higher Strehls ( 80% at K)  improved sensitivity
Lower backgrounds  improved sensitivity
Improved PSF stability & knowledge  improved photometry, astrometry
& companion sensitivity
2. Increased sky coverage & Multiplexing
• Improved tip/tilt correction  improved sky coverage
• Multiplexing  dramatic efficiency improvements
 Much broader range of science programs
3. AO correction at red wavelengths
•
Strehl of 15 - 25% at 750 nm  highest angular resolution of any existing
filled aperture telescope
4. Instrumentation to facilitate the range of science programs
7
Key performance metrics:
Strehl vs. observing wavelength
H
Ca
Triplet
NGAO
Current
NGS
Current
LGS
8
System Architecture
•
•
•
•
Tomography to measure
wavefronts & overcome
cone effect
AO-corrected, IR tip-tilt
stars for broad sky
coverage
Closed-loop AO for 1st relay
Open-loop AO for
deployable IFUs & 2nd relay
9
NGAO System Design Phase
Status
NGAO System Design Phase
•
•
System Design Phase. Oct/07 to Apr/08.
Executive Committee established to manage this phase:
–
•
Wizinowich (WMKO, chair), Dekany (Caltech), Gavel (UCSC), Max (UCSC,
project scientist)
Deliverables:
–
–
–
Science & Observatory requirements & flow down to system requirements
Performance budgets, functional requirements, system & subsystem
architectures
Management plan for remaining NGAO phases
11
System
Design
Milestones
Requirements 
Performance Budgets +
Trade Studies 
System Architecture +
Functional Requirements 
Subsystem Design +
Functional Requirements 
#
MILESTONE
DATE
STATUS
1
SD SEMP Approved
10/9/06
Complete
2
SD phase contracts in place
10/27/06
Complete
3
Science Requirements Summary
v1.0 Release
10/27/06
Complete
4
System Requirements Document
(SRD) v1.0 Release
12/8/06
Complete
5
Performance Budgets Summary
v1.0 Release
6/15/07
Complete
6
SRD v2.0 Release
5/22/07
Nearly complete
7
Trade Studies Complete
6/22/07
Complete
8
SRD
v3.0 Release
9/7/07
Not started
9
System Design Manual (SDM)
v1.0 Release
9/21/07
Complete
10
Technical Risk Analysis
V1.0 Release
9/21/07
Nearly complete
11
Cost Review Complete
12/7/07
Some work as part of
system architecture
12
SDM
v2.0 Release
2/12/08
13
System Design Review
Package Distributed
3/4/08
14
System Design Review
3/31/08
15
SDR Report & Project Planning
Presentation at SSC meeting
4/14/08
Management Plan
12
System Design Products
• All products maintained at NGAO TWiki site
(just Google NGAO)
including:
– Requirements documents (Science case, System & Functional)
– Performance budget reports (wavefront error & encircled energy,
astrometry, photometry, companion sensitivity &
throughput/emissivity)
– Model assumption & validation reports (total of 14)
– Trade study reports (total of 23)
– Management plans & reports
Goal of NGAO shared-risk science in 2013
13
Science Cases & Requirements
Outline
• What is complementary and scientifically unique
about Keck NGAO?
– JWST, ALMA, TMT
– Other ground-based observatories
• “Science Cases” for NGAO: what are “science
requirements” that will guide the design?
15
Key new capabilities for NGAO
1. Dramatically improved near-IR performance
2. Increased sky coverage & Multiplexing
3. AO correction at red wavelengths
4. Instrumentation to facilitate the range of science programs
16
Complementary to JWST, ALMA
• JWST: 2013
– Much higher sensitivity longward of K band
 NGAO emphasizing wavelengths > K band
– JWST: “Expect same resolution as HST below 2 m”
 NGAO has clear resolution advantage
– No multi-object IFU capability
• ALMA: 2012
– Spatial resolution as low as 0.01 to 0.1 arc sec (!)
– Complementary data on dust & cold gas
Our goal is to position NGAO to build on, and
complement, JWST & ALMA discoveries
17
Complementary to TMT
• TMT IRMS: AO multi-slit, based on MOSFIRE
– Slits: 0.12” and 0.16”, Field of regard: 2 arc min
– Lower backgrounds: 10% of sky + telescope
• NGAO with multiplexed deployable IFU’s
– Multi-object AO  better spatial resolution (0.07”) over full
field
– Backgrounds:  30% of sky + telescope
•
•
Pros for TMT: lower backgrounds, higher sensitivity
Pros for NGAO: higher spatial resolution, 2D information,
better wide field performance
18
Complementary with other
ground-based observatories
• Other ground-based observatories are largely focusing
on wide fields with modest performance, or on very high
contrast AO
• “Wide” field (by AO standards):
– Gemini South: Multi-conjugate AO
– VLT: Ground layer AO
• High Contrast:
– Gemini Planet Imager
– VLT SPHERE
19
Scale of new VLT AO projects is really big
• Hawk-I: 2012 with AO
– K-band imager, 7.5’ x 7.5’ field
• MUSE visible multi-IFU: 2012
– 1' field, x 2 seeing improvement
• MUSE visible narrow field IFU: 2012
– 7.5” field, ~5% Strehl at 750 nm
•
NGAO must strike balance between
scale/cost, risk, and science return.
•
Lesson from these VLT projects:
have courage, but be realistic too
20
Outline
• What is complementary and scientifically unique
about Keck NGAO?
– JWST, ALMA, TMT
– Other ground-based observatories
• “Science Cases” for NGAO: what are “science
requirements” that will guide the design?
21
Categorize science cases into 2 classes
1. Key Science Drivers:
– These push the limits of AO system, instrument, and
telescope performance. Determine the most difficult
performance requirements.
2. Science Drivers:
– These are less technically demanding but still place
important requirements on available observing
modes, instruments, and PSF knowledge.
22
Key Science Drivers
(in order of distance)
1. Minor planets as remnants of early Solar System
2. Planets around low-mass stars
3. General Relativity at the Galactic Center
4. Black hole masses in nearby AGNs
5. High-redshift galaxies
23
Key Science Drivers
(in order of distance)
1. Minor planets as remnants of early Solar System
•
I-band AO; high contrast; astrometry
2. Planets around low-mass stars
•
High contrast at J, H bands
3. General Relativity at the Galactic Center
•
Precision astrometry and radial velocities
4. Black hole masses in nearby AGNs
•
Spatially resolved spectra at Ca triplet (8500 Å)
5. High-redshift galaxies
•
Multi-IFU spectroscopy; low backgrounds; high sky coverage
24
Some Science Requirements from
Key Science Drivers (physical)
Wavelength
0.7 to 1.0 µm
Galactic & Solar System science, nearby AGNs
0.9 to 2.45 µm
All
Wavefront error
≤ 170 nm
Tip tilt error
≤ 15 mas over
≥ 30% of sky
All Solar System, planets around low-mass stars,
debris disks, nearby AGNs, QSO hosts, lensed
galaxies
≤ 3 mas
Galactic Center
50% ensquared
energy
within 70 mas
High z galaxies, Galactic Center radial vel’s
over ≥ 30% of sky
IFU field of view
≤ 3"
High-z field galaxies
Imaging field of
view
≥10"
Galactic Center
30"
Reference field of view for design study
25
Some Science Requirements from
Key Science Drivers (performance)
Background
≤ 30% over unattenuated
sky+telescope background.
Goal: ≤ 20%
High-redshift science
Astrometric precision
100 µas
Galactic Center
500 µas
Exo-planet primary mass
≥ 30% (areal average over
all sky)
Extragalactic science, TNOs, ...
Sky coverage fraction
26
Instrument Priorities from Key Science Drivers
Narrow field:
1.
2.
3.
4.
Multi-object:
1. Deployable nearNear-IR imager
IR multi-object IFU
Visible imager
Near-IR IFU (OSIRIS?)
Visible IFU
27
Some Science Cases have specific
observing requirements
• Efficient surveys: (e.g. asteroid companions and planets
around low-mass stars)
• Optimizing overall science output of the Observatory
– “Seeing” and AO correction are variable
– Requirements on ability to switch to NGS, and to other instruments
– What kinds of “flexible observing” might be appropriate?
28
Science Requirements from
Science Drivers (short summary)
Requirement
l (µm)
Field of view diameter (")
Field of regard diameter (")
Pixel size (mas)
Minimum # of IFUs
IFU separation
AO Background
Sky coverage
High order WFE (nm) for ≤ 5" fov
Tip/tilt error (mas)
50% Ensquared energy (mas)
Visible
Imager
Spectrograph
0.7-1.0
0.7-1.0
≥3
≥ 2 (goal ≥ 3)
na
na
≤ 7 (Nyquist at R)
na
na
na
na
na
na
na
≥ 30% for X3
≥ 30% for X3
≤ 170
≤ 170
≤ 15
≤ 15
na
≤ 25
Companion sensitivity
Photometry (mag)
DI ≥ 7.5 at 0.75" for S1b
g: ≤ 0.05 relative for
na
na
Astrometry (mas)
≤ 1.5 relative for S1b
na
•
Near-IR
Imager
Spectrograph
1.0-2.4 (+Y&z)
1.0-2.4 (+Y&z)
≥ 15 for X4b
≥4
na
na
≤ 13 (Nyquist at J)
na
na
na
na
na
≤ 30% of total
≤ 30% of total
≥ 30% for X1,X3,X4b
≥ 30% for X3,X4a
≤ 170
≤ 170
≤ 15 for sky cover; ≤ 3 for G2
≤ 15
na
≤ 25
DH ≥ 5.5 at 0.5" for S1b; DJ
≥ 8.5 at 0.1" & DJ ≥ 11 at
0.2" for G1
na
≤ 0.05 relative for S1&G1
na
≤ 1.5-2 for S1b&G1; ≤ 0.1
for G2a
na
Near-IR
Deployable IFU
1.0-2.4 (+Y&z)
≥1x3
≥ 120
≤ 35 (2 pixels/spaxel)
4
> 1 IFU in 10x10"??
≤ 30% of total
≥ 30% for X2
derived
derived
≤ 70
na
na
na
An “eye test” here, but printed out on your handout sheets.
Please send us your input!
29
Science Drivers
(in order of distance)
1.
2.
3.
4.
5.
6.
7.
Asteroid size, shape, composition
Giant Planets and their moons
Debris disks and Young Stellar Objects
Astrometry in sparse fields
Resolved stellar populations in crowded fields
QSO host galaxies
Gravitationally lensed galaxies
Requirements based on these Science Drivers are still
under discussion - we need your input!
30
NGAO will allow us to tackle
important, high-impact science
1. Near diffraction-limited in near-IR (Strehl >80%)
•
•
•
Direct detection of planets around low-mass stars
Astrometric tests of general relativity in the Galactic Center
Structure & kinematics of subcomponents in high redshift galaxies
2. Vastly increased sky coverage and multiplexing
•
Multi-object IFU surveys of distant galaxies
3. AO correction at red wavelengths (0.7-1.0 m)
•
•
•
Scattered-light studies of debris disks and their planets
Masses and composition of asteroids and Kuiper Belt objects
Mass determinations for supermassive black holes
31
Science Case Presentations today
• Precision astrometry at Galactic Center & in sparse
fields
– Brian Cameron and Jessica Lu
• Spectroscopy of high-redshift galaxies
– Chuck Steidel and David Law
• Gravitationally lensed galaxies
– Tommaso Treu and Phil Marshall
Intended to illustrate NGAO science
requirements development process
32
NGAO System Design:
System Architecture
Element
System
Architecture
Benefit
Eases packaging and cooling
1st Relay
(~200" FoV)
Existing DM technology
Maximizes tip/tilt sky coverage
Reduces MOAO risk
2nd Relay
(30" FoV)
Utilizes low-cost MEMS DM
Compact size requires small optics
Variable-Radius
LGS Asterism
Robustness to Cn2(h) variations
MOAO-Corrected NIR Tip/Tilt
Sensors
Maximizes sky coverage
PSF Monitoring Capability
Field-dependent PSF estimation
Routine system optimization
K-mirror Derotator
Fixed gravity
Output instrument Switching Mirror
Rapid instrument changes
34
NGAO Fields of Regard
5 LGS variable
radius asterism
180" FoR for tiptilt star selection
202" LGS patrol
range
3 tip/tilt stars
Central
LGS
3 tip/tilt
stars
5 LGS
on 11” radius
Roving
LGS
Multi-object
deployable
IFU FoV
120 arcsec
1st Relay / DNIRI
Field of Regard
30 arcsec
2nd Relay / Precision AO
Field of Regard
35
System Design
Progressing
Woofer DM
589 nm Light
LGS OSM
f/15 AO
Relay
Telescope elevation
bearing
K-mirror image
de-rotator
Visible
imager
Near-IR imager
Keck I or II
right Nasmyth
platform
LGS
wavefront
sensors on
focus stages
OMU Bench
IFU and
tip-tilt
OSM
2 channel IFU
spectrograph (1 of 3)
Tip-tilt sensor (1 of 3)
f/45 narrow field AO
relay
Narrow field selection
mirror
Near-IR IFU
(OSIRIS)
36
Conclusion: NGAO Capabilities
1. Dramatically improved near-IR performance
•
•
•
Significantly higher Strehls ( 80% at K)  improved sensitivity
Lower backgrounds  improved sensitivity
Improved PSF stability & knowledge  improved photometry, astrometry
& companion sensitivity
2. Increased sky coverage & Multiplexing
• Improved tip/tilt correction  improved sky coverage
• Multiplexing  dramatic efficiency improvements
 Much broader range of science programs
3. AO correction at red wavelengths
•
Strehl of 15 - 25% at 750 nm  highest angular resolution of any existing
filled aperture telescope
4. Instrumentation to facilitate the range of science programs
Enables wide variety of new science within interests of Keck Community
37