magellan 20m project - national optical astronomy observatory …€¦ · telescope steering group,...
TRANSCRIPT
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Magellan 20m Project
Presenters: Wendy Freedman, Carnegie Observatories
Roger Angel, U. Arizona
Steve Shectman, Carnegie Observatories
Matt Johns, Carnegie Observatories
GSMT Science Working Group Presentation
Los Angeles, CA
March 18, 2003
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Magellan 20m Introduction & Science
Presenter: Wendy Freedman
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Magellan 20-Meter Telescope
[www.ociw.edu/20meter]
GSMT Committee Meeting
March 18, 2003, LAXPresenters: W. Freedman, R. Angel, S. Shectman, M. Johns
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Magellans I and II domes
The Magellan 6.5 mTelescopes
CarnegieHarvardSmithsonianMITArizonaMichigan
Las Campanas
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The Magellan 20-meter Telescope is…
• Partnership:A consortium of partners currently including Carnegie, Harvard/Smithsonian, University of Arizona, MIT, and the University of Michigan
• Telescope:Roger Angel design conceptSeven 8.4-meter mirrors
• MOU:The partners have committed to funds forthe 18-month conceptual design phase.
• Governing Bodies:Magellan 20 Board: each partner has 2 members. Telescope steering group, Science / Instrumentation plus AO working groups have been established.
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The Magellan 20-meter Telescope Planned CharacteristicsMode
FOVFWHM@ 1 µm
Notes
Natural Seeing 15’ 0.4” Gregorian focusmulti-object and high-resolution spectrographs
Single-DM Adaptive 20” 0.007” Natural and Laser guide stars ; HR imaging and near-IR IFU
Ground-layer Adaptive
5’ 0.25” Natural guide stars; HR imaging, deep nearIR multiobjectspectroscopy and low-SB IFU
MCAO* 1.6’ 0.007” Natural and Laser guide stars ; IFUs / high-resolution imaging
20/20 Interferometer*
1’ 0.0017” Requires 2nd telescope and track; direct high resolution imaging of extrasolar planets
* upgrade paths
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Science Priorities for the 20m
1. Origin and Evolution of Galaxies and Structure in the Universe
2. The Nature of Dark Matter and Dark Energy
3. Formation and Growth of Black Holes
4. Stellar Populations and Chemical Evolution
5. Origin of Stars and Planets
6. Physical Properties of Extra-solar Planets
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Origin and Evolution of Galaxies and Structure in the Universe
Critical issues:1. First light and reionization
2. Assembly of galaxies and clusters
3. Energetics of the IGM
4. Origin of the Hubble SequenceCMB (WMAP image): seeds ofgalaxy and LSS formation
Observational approach:1 High resolution studies of z > 6 QSOs, deep Lyα
surveys in near-IR for first light
2. Sub-L* redshift surveys over large volumes
3. Tomography of IGM using Lyman-break galaxies
4. Dissection of galaxies with natural seeing and AO-fed IFUs in visible and near-IR
Sloan z > 6 quasar
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Origin and Evolution of Galaxies and Structure in the Universe (2)
Ly α spectroscopy of high-redshift galaxies:- star forming galaxies at 7 < z < 18:- spectroscopy with IR detectors on M20 - e.g., 10 hours AO near-IR spectrometer- substantially higher sensitivity than JWST
Ly α emission-linespectroscopy
JWST vs M20+AO
Examples:
Galaxy and Structure Evolution:- deep spectroscopic surveys, sub-L* galaxies- 6-10m telescopes insufficient sensitivity- wide-field spectrograph for M20 - reach I~26 [ 0.01 L* at z = 1
0.1 L* at z = 3sfr of 10 M/yr at z = 5]
- hundreds of simultaneous spectra at R~4000Growth of structure in the universe
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Origin and Evolution of Galaxies and Structure in the Universe (3)
Examples (continued):
Tomography of the IGM
Baryons in the Universe:- Most baryons in universe in warm IGM- Wide-field multiobject spectrograph- 20m can use galaxies as probes of Ly α
forest instead of sparse QSOs- 5000 objects/sq. deg to AB~24
Galaxy Structure and Formation:- galaxy kinematics and spectral properties - IFU on M20 could extend volume of
universe available for study by 300,000with single-DM adaptive mode
- intrinsic shapes, orbital structures, ages,metallicitiesIFU dissection of nearby galaxies
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The Nature of Dark Matter and Dark Energy
Critical issues:1. What is the nature of dark matter?
2. What is the equation of state for the dark energy in the universe? Cluster gravitational arcs
observed with Magellan (BVI)
Observational approach:1. Detailed dynamical studies in DM-dominated
environments (e.g. rich clusters, dSph galaxies)
2. High-redshift SNe studies in the rest-frame visible to test for evolution in SNe properties
Spectroscopy of z ~ 1.5 SNe to confirm down-turn in type Ia Hubble diagram
SNe Ia Hubble diagram
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Formation and Growth of Black-Holes
Critical issues:1. Formation epoch for first black holes
2. Growth and feeding of black holes
3. Connection between BH mass and galaxies bulges
Observational approach:1. Near-IR searches for faint first-light AGN
2. Trace evolution of faint-end AGN luminosity function
3. AO-fed spectroscopy of narrow-line regions of low-luminosity AGN to understand accretion modes
4. Velocity dispersions and bulge masses at z ~ 0.3 with AO-fed spectrometers
Black-hole mass measurement
BH mass – bulge mass correlation
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Stellar Populations in GalaxiesCritical issues:1. Environmental dependence of IMF
2. Star formation histories in galaxies
3. Chemical enrichment history across Hubble types and masses
4. The first stars: extremely metal-poor stars in the halo of the Galaxy
Observational approach:1. Deep AO imaging in Galactic Center and Local Group
and beyond
2. AO-enhanced near-IR echelle spectroscopy of Local-Group red giants (R~25,0000)
3. Multi-object composite spectra of giants beyond Local Group
4. Super-high SNR (~1000), high resolution spectroscopy of extreme metal poor stars (R~25,000)
Arches cluster in the GC
Leo I color-magnitude
diagram
Simulated SNR = 30 spectra for LG giants
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Origins of Stars and Planets
Critical issues:1. What determines stellar, brown-dwarf
and planet mass functions?
2. Environmental influence on planet formation process
3. Evolution from proto-planetary disks to planetary systems
Large segments enable detection of extra-solar planets in reflected light
Radial velocity detection of planets Observational approach:
1. Direct detection of sub-stellar and planetary bodies in near IR from reflected and reprocessed radiation from central star
2. Extend radial-velocity searches to wider range of stellar types
3. Physical studies of debris disks in mid-IR with AO-fed chronographic imagers and spectrometers (key composition diagnostics)
Circumstellar debris disk
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Physical Properties of Extra-Solar Planets
Critical issues:1. Physics of planetary atmospheres
2. Survival of “hot Jupiters”
3. What are the distributions of planetary temperature, albedo, mass, size?
Nulling interferometry at 10 µ m with Magellan
Observational approach:1. IR spectroscopy with chronographic and nulling
interferometric imaging spectrometers.
2. Spectroscopic monitoring of transiting systems
M20 direct imaging
M20 nullinginterferometry
Model spectra of giant planets
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Magellan 20m Concept & Applications
Presenter: Roger Angel
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Magellan 20 telescope•Seven 8.4 m segments•Equivalent diameter 21.5m•18m Focal Length primary•F/10 Gregorian adaptive secondary•Design under study by Magellan team
. Building 57 m diameter by 36 m wide cylinder, 50 m heightTelescope can rotate inside the building when zenith pointing and move in elevation either toward or away from the slit.
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Schematic diagram
El axis behind primary vertex
Foci shown are confocal, but can be moved by reshaping primary and secondary figures
G4 focus is folded for vertical axis and flexure-free field rotation
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Location of instruments
behind primary
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LBT and 20/20 telescope drawn to the same scale
LBT and M20 to same scale (M20 now is a bit bigger, C rings have gone from LBT’s 14 m to 18 m diameter)
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CELT Magellan 20
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Fast optical design short, 18 m focal length primary
– f/0.7 for 25 m primary envelope – field of view holds up well with fast primary – seeing limited over 12 arcminutes at f/10
Mechanical advantages of fast primary:
Stiff mount, > 5Hz resonant frequency with Davison C-ring mount
secondary wind torque much reduced
Optical advantages of f/0.7 + Gregorian f/10 deformable secondary:
secondary conjugates to ground layer
AO engineering with artificial star at prime focus
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M 20 will use large primary segmentsHighly aspheric polishing and support techniques proven for 8.4 m substrates.
Hyperboloidal primary surface made up from seven 8.4 m segments,
-center + ring of 6 identical off axis
-21.5 m effective area
Advantages of large segments:8.4 m, f/1.14 LBT I surface, 24 nm rms
- simple control system
- proven excellent performance (rigidity, thermal equilibration)
- proven accurate wavefront over large areas
- proven support systems allow large scale figure control to 0.1 arcsec
- hexapod positioning for detailed matching to parent surface
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M20 segmented deformable secondary
World’s first adaptive secondary at MMT
PSF in H band at MMT, FWHM 0.059, Strehl=40%
Will use deformable secondary technology demonstrated at the MMT
7 secondary segments conjugated to primary segments
8.4 m pri => 0.9 m secondary segment 636 actuators/segment, 4500 in all. Fast go-to, < 1 msec
3 levels of control:
1) fixed shape – seeing-limited
2) ground layer correction – improved seeing
3) AO imaging – diffraction limit
No compromise of either infrared or optical.
Adaptive secondary technology has large stroke (no physical contact of actuators) No need for separate tip/tilt mirror
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Diffraction PSF for M20 with AO The secondary support structure is designed to leave completely unobscured the 6 round outer segments. Secondary spider is from upper 9 m hexagonal frame
68% encircled energy in central core (vs 84% for filled circular aperture)
FWHM 18 mas at 2.2 µm
Modeled MCAO realization of PSF, K band, 50” off axis
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unique optical features give scientific edge:
Deformable Gregorian secondary with fast primary conjugates to 150 m above telescope – optimally placed for ground layer AO correction (0-300 m) for wide field wide field cover.
Large segments – smooth wavefront and clean diffraction allow direct imaging of known, illuminated exoplanets
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Ground layer correction with Gregorian secondary• For fast M20 primary, Gregorian secondary conjugates to short distance above telescope for especially wide corrected field
• Correction limit set by secondary fitting error and tilt anisoplanatism for corrected layer at height z, Strehl S = exp(–6.88(θ(z-z0) /r0)5/3 –( 0.4 Dx/r0)5/3)
For M20, z0 = +150 m (height of secondary conjugate); Dx = 0.3 m (actuator spacing projected to wavefront)
0.680.681.25
Strehl after correction
r0 ground layer(m)
Wavelength (mm)
0.800.951.65
0.390.400.9
Example:
edge of 5 arcmin field (θ=2.5’) layers at ground or 300 m r0 (total) @ 0.5 µm = 0.16 m (0.62 arcsec seeing in V) half total seeing arises in g. layer
Conclusion: ground layer largely corrected over 5 arcmin field in near IR Improvement of ~ 30% in FWHM should be possible, anywhere on skyMethod to be tested with same 0.3 actuator spacing with MMT AO secondary
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Example of partial AO correctionMMT adaptive secondary closed at 10 Hz update rate
Useful correction despite large residual error
GCAO modeling in progress (Lloyd-Hart)
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Direct detection of known (old) extra-solar giant planets in reflected light with M 20
Planet brightness from stellar illumination ~ inverse square law:
10-5 star at 0.05 AU (51 Peg) to 10-9 star at 5 AU (Jupiter)
For PSF after AO correction, speckle and photon noise in residual starlight should fall off slower than 1/r2, so closest-in planets most favorable for detection
Inner radius limit set by optical imperfections and capability for apodization or nulling to suppress diffraction
Big, clean segments of M 20 enable good suppression for:
1) imaging at ~ 1 AU i.e. ~ 0.1 arcsec
2) spectroscopy at ~ 0.1 AU via interferometric suppression (roasters)
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Big segments enable direct detection of
known extra-solar giant planets in habitable zone
5.11.3 × 10-8981.48HD160691-39 º5.4 1.8 × 10-8981.26HD147513
DecV star
Planet/star (J band)
Max. sep. mas
D (AU)
star
Apodized pupil(24% transmission)
-51
º
-51
ºSingle 1 msec frame
� Simulation by J Codona for 20 m telescope, ring of six 8.4 m segments.
� Segments apodized individually for diffraction ~10-6
from 60-120 mas radius in J band (dark annulus).
� AO correction assumes: turbulence moving 10 m/s from left to right. Correction at 1 msec intervals Residual errors yield background 10-5 in annulus
� 4.6 s average shows 10-6 planet at 80 mas, 10-o-clock. 1.4×10-8 planet will require 8 hour integration 4.6 sec, 10-6 planet @ 80 mas, J
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AO requirements met by M20 systemM20 design has adaptive secondary with 650 actuators per 8.4 m segment, i.e. spacing ∆x = 30 cm .
For bright stars, wavefront error dominated by spatial fitting.
Strehl S = 1- ∆2 = 1- (0.4∆x/r0)5/3 = 0.91 in J band for r0~ 50 cm
This is higher Strehl than yet achieved, but should be possible given:
* accurate wavefront measurement bright stars * high actuator density * smooth 8.4 m segments. (Magellan II has S = 97% @ 1.25 µm.)
The strength of residual scattered light in the 0.06 – 0.12 arcsec annulus is determined by low order residual errors, of wavelengths ~ 2 m.
These will be measured directly, free from non-common path errors, from the complex amplitude of the focal plane speckles in the annulus (Angel, 2003)
Projected fluxes of a few photons/speckle/msec in J band allow for this
Successive errors will be decorrelated by use of phase tracking algorithm.
Adaptive secondary allows for fast, accurate correction of 2 m scale errors
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2. Spectra of giant planets with M20 by interferometric nulling of star
Effective baseline b=13 m, for phase groupings shown. Accurate phase/amplitude servo using (still huge) nulled star signal (few thousand counts/msec)
Tplanet = ¾ sin2(πθb/λ), θ = angular separation
Tstar = ¼ (πab/λ)2, a = star radius
Two domains of interest with planet/star ratio ~ 10-5:
1) bright roasters at 0.05 AU (few mas resolved at ~ 0.9 µm where star suppressed by factor 1000)
2) EGPs at 0.25 AU (~ 20 mas resolved at 3.5 – 5 µm), Ts<.0001
Exposures of several hours should yield spectra with R~ 50 - 500
Nulling interferometry at 10 µm from Magellan, masked as with 2 ellipses (P. Hinz)
Nulling interferometer transmission
Phase sequence for M20 nuller
constructive destructive
Direct detection with Bracewell nulling used to suppress star by factor ≥1000.
Method: Light from the six M20 mirror segments combined interferometrically via single mode fibers, with phases modulated to synthesize a rotating Bracewell nullinginterferometer
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Model spectra of giant planets near stars by Sudarsky et al.
Regions accessible with M20 by direct imaging (green) and nulling interferometry (yellow)
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Known old giant planets accessible by M20
Star Dec Type Semimajor axis(AU)
sep (mas)
V mag Notes
HD 147513 -39 G5 V 1.26 98 5.4 Direct J imaging
HD 160691 -51 G3 IV-V 1.48 97 5.1 “
HD 1237 -80 G6 V 0.51 29 6.7 Nulling in L band
GJ 86 -51 K1 V 0.117 11 6.2 Nulling in H, K bands
HD 217107 -02 G8 IV 0.072 4 6.2 Nulling at 1 µm
51 Peg +21 G2.5 IVa .052 3.7 5.5“
Tau Boo +17 F6 IV .047 3.4 4.5 “
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Upgrade paths
MCAO
20/20
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MCAO for M20, design and simulation by Mark Milton and Mike Lloyd-Hart
Uses 10 sodium laser beacons in two pentagons, at 60 and 78 arcsec radius.Nearly complete sky cover at the Galactic pole – needs 18th magnitude tip-tilt NGS on axis.Model used 7 layer atmosphere, integrated r0=0.9m @ 2.2 µm.Correction with adaptive secondary plus 2 additional deformable mirrors conjugated at3.8km and 12.8km respectively, 500 modes each.
At this stage, no time delay or noise in wavefront sensor is modeled, but results include errors from tomographic reconstruction and 500 mode limitation. Frames are for K band, 25 realizations superposed
No correction
With MCAO, on-axis, Strehl=0.79 FWHM=18 mas
With MCAO, 50” off-axis, Strehl=0.49
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M20 concept allows for later incorporationinto track-mounted 20/20 pair
When two track-mounted 20 m telescopes combined:
* resolution is increased by 4 times with no loss of point source sensitivity or field of view
* greatly increased thermal sensitivity to exoplanets in Bracewell nulling configuration
The first telescope has no track mount initially, but is made compact and stiff to allow for upgrade
Las Campanas site has room to add track and second telescope later
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resolution and sensitivity -single vs double telescope
The reconstructed image from 20/20 will have 4 times the resolution of a single 30 m dish.
Angel has shown that the limiting signal/noise ratio for point sources against sky background is reduced by only 0.3 mag if losses are the same.
In practice, the interferometric combination for the co-moving telescopes of 20/20 requires minimal additional optics, with little loss. 10 σ magnitude limits for 8 h total integration are as follows:
28.128.829.930 m
27.728.529.620/20
KHJband
Note 4 mas resolution for MCAO-corrected K band extends over a 1 arcmin field –richness of Schmidt plate
Simulated 20/20 sensitivity with sky noise by Keith Hege and Laird Close. Stars in galactic bulge of galaxy at 100 mpc
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Magellan 20m Instruments
Presenter: Steve Shectman
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Instrument Concepts for Magellan 20• Wide-Field Optical Spectrograph
– >10 arcmin, >100 objects
• High-Resolution Optical Spectrograph
– R > 50000
• Near-IR AO Imager
– 10” field, .003” pixels (2K)
• Near-IR AO Integral Field Spectrograph
• Mid-IR AO Imager
• Ground-Layer AO Near-IR Imager
– 10 wavefront sensors, 5’ field, .07” pixels (4K)
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• AO Instruments Adaptive Secondary
– Final instrument focal ratios are mild
• Wide-Field Spectrograph Optics, Structure
– Imaging Spectrograph
– Limitations on large optics, mosaic gratings
– Fiber Spectrograph
– Fiber image slicers / IFU’s
– ADC, telecentric corrector
Instruments Telescope
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Imaging Spectrograph
• Reflective Optics (Schmidt cameras)
– Small angular field of view
– Compensated by large size (>1m)
– Large mosaics ⇒ high spectral resolution
• Refractive Optics
– Large angular field of view: Match to Gregorian
– Size limitations (0.5m?)
– Moderate spectral resolution
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• 13’ dia. field• 36-chip mosaic
• R=4000 at 8500A• 2000A spectral coverage
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Fiber SpectrographsTelecentric corrector with ADC ?
• 7 x 0.25” ⇒ 100 micron fibers @ f/3.5
• Charge-Shuffling! 150 mm beam?
• Red Spectrographs
– 4-order echellette, R~5000
– 7 fiber heads per spectrograph (3.5 objects)
– 30 spectrographs
• Blue Spectrographs
– Single order, R~1000
– 35 fiber heads per spectrograph
– 6 spectrographs
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Field diameter =
130mm
84.625126
RED: echelletteMarconi CCD42-90:
2048 x 460813.5µm pixels27.6 x 62.2 mm (active)28.2 x 67.3 mm
RGL grating:Blaze: 26.7ºGr/mm: 150R ~ 5050 per 100µm w/ FL 500
o 10,000A (9270-10980, 87mm)o 8560A (8020 - 9270, 73.9mm)o 7490A (7070 – 8423, 64.2mm)o 6660A (6320 – 7070, 56.8 mm)
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Magellan 20 Instrument Process• Current work is being done by an ad-hoc telescope
definition group
– To explore impact on telescope design
• Instrument study groups will be formed by SAC
– To develop serious instrument designs
– Detailed consideration of science goals
• Project budget will contain funds for an initial
complement of instruments
– Not necessarily comprehensive
– Instrument competition several years in future
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Magellan 20m Project
Presenter: Matt Johns
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Baseline Magellan 20m Telescope• 20m – 22m Class telescope
– Composed of six or seven 8.4-m primary mirrors
• Compact telescope structure
• High modal performance
• Reduced mount & enclosure cost
• Staged approach to adaptive optics
– Adaptive Gregorian secondary mirror
• Facility instruments developed as part of the project.
• Upgrade paths for the future.
– Higher-order adaptive optics
– Interferometry e.g. 20/20
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• Project follows the successful completion of the Magellan
6.5m telescopes & current developments on LBT.
• Magellan science examples:
HDF
Natural Development Path
6 minute I-band exposure. FHWM = 0.25”
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Magellan 6.5m Results
Composite of 400 s
g’, r’, I’ exposures.
Fwhm = 0.35” – 0.40”
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These telescopes really perform!
Magellan 6.5m Results
Soft xray transient
XTE J1550-56
I-band
fwhm = 0.30”
MagIC CCD Imager
on
Magellan 1
By Paul Groot
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Telescope structures
Experience in building stiff mounts.
Magellan LBT
10 Hz lowest modes 8 Hz lowest modes
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• Magellan 20 concept utilizes mirror technology developed on
3.5m, 6.5m, & 8.4m telescope projects
– Monolithic cast mirrors- high figure accuracy & thermal control.
– Capability for producing very fast aspheric optics (M20 f1~0.7)
– Existing production facility is part of the consortium.
Magellan 2
LBT 1
Optics Fabrication
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Magellan 20 Mirror Production
• SOML upgrades– New 8-m LOG allowing pipeline processing for mirror generation &
polishing currently being installed.– Assembly area enlargement for staging.– Modify test tower for 18m f.l. off-axis aspheric segments.
• Figuring aspheres– Metrology design & test procedures (Phase A study underway).– CNC control generating & polishing- study (Phase A study)– Technology demonstrator: 1.8m off-axis asphere (Martin/AFOSR)
• Support system revisions for 3-axis operation (Phase A study).
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Pacing item: Mirror Production
Mirror production rate- increased staff
Goal:
7 segments
~7.3 years
Projections based on:
• Experience at 3.5m, 6.5m, 8.4m
• SOML upgrades
• 1.8m technology demonstrator
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Adaptive OpticsProject takes advantage of institutional AO expertise
-Adaptive secondary mirrors, wavefront sensors, analysis & control
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• Strong instrument groups exist at all six institutions.
MIKE Echelle spectrograph
Instrument examples:
OCIWOCIW
Multi-object spectrograph
OCIW
Instrument Development
PANIC IR imager
MagIC CCD Imager MIRAC/BLINC MIR imager/interferometer
HECTOCHELLE
Harvard/MIT
SAO U. Arizona
and more.
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• Developed potential sites & infrastructure at LCO.
Magellan (Manqui) Campanas Pk.Alcaino Pk.
La Mollaca Alta(behind)
Campanas PK.
Chilean Sites
Site test data & operations going back well over a decade.
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Project Phases
Phase A: Conceptual Development
Phase B: Engineering/Design
– Start of mirror production
Phase C: Construction
Phase D: Commissioning
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Schedule
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• Science case
• Primary mirror production
• Optical system design
• Telescope structure design
• Optical alignment & phasing
• Adaptive optics *
• Adaptive secondary mirrors *
Phase A Studies
• Primary mirror supports
• Mirror coating *
• Instrument concepts *
• Enclosure studies
• Site survey *
• Operations model
• Cost studies
Active development underway Planned *NSF/GSMT support
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Magellan 20m Summary
Presenter: Wendy Freedman
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Concluding RemarksThe Magellan 20-meter telescope:• consortium nucleus with expertise in telescopes, instrumentation and
operations; proven success; established infrastructure in Chile
• building on successful technology, incorporating new capabilities enabling powerful gains in sensitivity and angular resolution
• exciting science goals for the baseline design configuration, covering a broad range of topics including the formation and assembly of galaxies, black holes, stars and planets, areas overlapping the GSMT science goals
• the large-segment design is extremely well-suited for detection of close-in planets since big, clean segments enable excellent suppression of diffraction
• we have funding for conceptual design phase; signed MOU to begin fundraising efforts; seeking additional partners
• we represent a significant fraction of the US national astronomy community,AND we have the opportunity to bring in substantial amounts of private money into US astronomy