1 the large synoptic survey telescope status summary steven m. kahn slac/kipac
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The Large Synoptic
Survey Telescope
Status SummarySteven M. Kahn
SLAC/KIPAC
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LSST Technical Concept• 8.4 Meter Primary
Aperture– 3.4 M Secondary– 5.0 M Tertiary
• 3.5 degree Field Of View• 3 Gigapixel Camera
– 4k x 4k CCD Baseline– 65 cm Diameter
• 30 Second Cadence– Highly Dynamic
Structure– Two 15 second
Exposures• Data Storage and
Pipelines Included in Project
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Why is the LSST unique?Primary mirror
diameterField of view
(full moon is 0.5 degrees)
KeckTelescope
0.2 degrees10 m
3.5 degrees
LSST
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Relative Survey Power
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The Essence of LSST is Deep, Wide, Fast!
* Dark matter/dark energy via weak lensing * Dark matter/dark energy via supernovae* Galactic Structure encompassing local group* Dense astrometry over 30,000 sq.deg: rare moving objects* Gamma Ray Bursts and transients to high redshift* Gravitational micro-lensing* Strong galaxy & cluster lensing: physics of dark matter* Multi-image lensed SN time delays: separate test of cosmology* Variable stars/galaxies: black hole accretion* QSO time delays vs z: independent test of dark energy* Optical bursters to 25 mag: the unknown* 5-band 27 mag photometric survey: unprecedented volume* Solar System Probes: Earth-crossing asteroids
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Principle LSST Science Missions• Dark Energy / Matter
– Weak lensing - PSF Shape/ Depth / Area– Super Novae + Photo z – Filters /
• Map of Solar System Bodies– NEA – Cadence – KBO -
• Optical Transients and Time Domain– GRB Afterglows – Image Differencing– Unknown transients -
• Assembly of the Galaxy and Solar Neighborhood– Galactic Halo Structure and Streams from proper motions– Parallax to 200pc below H-burning limit
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LSST and Dark Energy
• LSST will measure 250,000 resolved high-redshift galaxies per square degree! The full survey will cover 18,000 square degrees.
• Each galaxy will be moved on the sky and slightly distorted due to lensing by intervening dark matter. Using photometric redshifts, we can determine the shear as a function of z.
• Measurements of weak lensing shear over a sufficient volume can determine DE parameters through constraints on the expansion history of the universe and the growth of structure with cosmic time.
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Color-redshift
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
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Cosmological Constraints from Weak Lensing Shear
Underlying physics is extremely simple General Relativity: FRW Universe plus the deflection formula. Any uncertainty in predictions arises from (in)ability to predict the mass distribution of the Universe
Method 1: Operate on large scales in (nearly) linear regime. Predictions are as good as for CMB. Only "messy astrophysics" is to know redshift distribution of sources, which is measurable using photo-z’s.
Method 2: Operate in non-linear, non-Gaussian regime. Applies to shear correlations at small angle. Predictions require N-body calculations, but to ~1% level are dark-matter dominated and hence purely gravitational and calculable with foreseeable resources.
Hybrids: Combine CMB and weak lens shear vs redshift data. Cross correlations on all scales.
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Measurement of the Cosmic Shear Power Spectrum
• A key probe of DE comes from the correlation in the shear in various redshift bins over wide angles.
• Using photo-z’s to characterize the lensing signal improves the results dramatically over 2D projected power spectra (Hu and Keeton 2002).
• A large collecting area and a survey over a very large region of sky is required to reach the necessary statistical precision.
• Independent constraints come from measuring higher moment correlations, like the 3-point functions.
• LSST has the appropriate etendue for such a survey.
From Takada et al. (2005)
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Constraints on DE Parameters
From Takada et al. (2005)
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Optical Design
0.6”
LSST Optical Design
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LSST Camera
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Camera Mechanical Layout
L1L3
Shutter
Filter
L2
Detector array
1.6m
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Focal plane array
3.5° FOV 64 cm
Raft = 9 CCDs + 1cm x 1cm reservedfor wavefront sensors
201 CCDs totalStrawman CCD layout4K x 4K, 10 µm pixels
32 output ports
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LSST Data Management Infrastructure
BaseCampCenter
Mirror Sites
ArchiveComputing
Center
TelescopeSite
PortalUser
101 to 2 kM1.2 GB/s
103 to 4 kM.4 GB/s
103 to 4 kM.35 GB/s
10-1 kM, .6 GB/s
Focal plane
PortalUsers
150 TB disk10 TFLOP
1 PB disk 25 TFLOP*
PortalUsers
GRID, Internet 2
15 TB disk, 5 TFLOP
Notes: B = bytes, b = bits
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LSST Partners• Research Corporation • U of Arizona • National Optical Astronomical Observatory • U. of Washington• Stanford U. • Harvard-Smithsonian• U. of Illinois• U of California – Davis• Lawrence Livermore National Lab• Stanford Linear Accelerator Center• Brookhaven National Lab• Johns Hopkins University
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LSST Project Structure
Camera
Steven Kahn, Sci.Krik Gilmore, Mgr.
Telescope/Site Charles Claver, Sci. Victor Krabbendam,
Mgr.
SystemEngineering
William Althouse
Science Working Groups
Data Management Timothy Axelrod,
Sci.Jeffrey Kantor, Mgr.
Science AdvisoryCommittee (SAC)
System Scientist &Chair of Science
CouncilZeljko Ivezic
Education & Public Outreach
Suzanne Jacoby
LSST Director Anthony Tyson
Steven Kahn, Deputy
Project ManagerDonald Sweeney
Victor Krabbendam, Deputy
LSSTC Board of Directors
John Schaefer, President
SimulationsDepartment
Phil Pinto
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Steering Committee Aronson (BNL) Burke (SLAC) Stubbs (Harvard) Tyson (UC Davis)
Camera Scientist Kahn (SLAC)
Camera Manager Gilmore (SLAC)
Marshall, ThalerSensor Design - GearySensor Deliverables - RadekaFEE - O'ConnorBEE - OliverWFS - (TBD)Guide Sensors - (TBD)Design & Metrology TakacsFEE Crate - O'Connor
Sensor/RaftDevelopmentRadeka (BNL)
Optical Design - SeppalaL1 - WhistlerL2 - WhistlerL3 - WhistlerFilters - RasmussenMechanisms - Hale
Optics Olivier (LLNL)
Integrating Structure - HaleRaft Module IntegrationRasmussenIn situ Monitoring & ActuationPerlThermal Systems - ThurstonFP Motion Control (TBD)
FP DewarAssembly
Schindler (SLAC)
Mechanisms - HaleCamera Body - HaleThermal Design - Thurston& ImplementationFP Motion Design - (TBD)FEA & Modeling - (TBD)Vacuum Systems - (TBD)Camera Electrical Sys. - OliverCooling Design - ThurstonCam/Tel Interface - AlthouseGroundingPower ConditioningWFS & GuidingContamination Analysis& Control (TBD)
Camera Design &Modeling
Gilmore- acting (SLAC)
FP ControlHousekeepingWFS & GuidingPower ConditioningExposure ControlThermal ControlMechanisms
Camera Controlsand Software
Schalk (UCSC-TBC)
Sensor Level - O'ConnorRaft Level - O'ConnorFocal Plane - RasmussenSky Calibration - GilmoreSimulations - Jernigan
CalibrationBurke (SLAC)
LSST CAMERA ORGANIZATION CHART______________________________________________
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SLAC Participation in LSST
• Faculty: Blandford, Burke, Kahn, Perl, Schindler
• Physics Staff: Gilmore, Kim, Lee, S. Marshall, Rasmussen
• Postdoctoral: Bradac, P. Marshall, Peterson
• Engring/Tech: Althouse, Hodgson, Rogers, Thurston
• Computing: Becla, Hanushevsky, Luitz
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Proposed Funding Model for the LSST
• Concept and Development Phase (2004 – 2008)– $15M from LSSTC members and private sponsors – $15M from the NSF– $18M from the DOE
• Construction Phase (2008 – 2013)– $120M from the NSF– $100M from the DOE– $50M from private sponsors
• Operations Phase (2013 – 2023)– ~$20M/year is estimated as total annual operations budget
($10M/yr for the observatory and $10M/yr for data management)
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Proposed funding and management configuration
NOAO
x
LSST Collaboration Institutions
Funding Sources
Potential relationships established by
MoA's
NCSALSSTC Staff
PMO xLSSTC
PMO: Program Management Office
x
SLACBNLLLNL
Universities
Universities
x
DOE NSFLSSTCPrivate
x
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Key R&D Issues• Telescope
1. Implementation of the wavefront sensor and stability of the correction algorithm2. Metrology for the convex, aspheric secondary3. Achieving 5-sec slew-and-settle specification
• Camera1. Development of focal plane sensor meeting all specifications2. Assembly of focal plane meeting flatness specification3. Fabrication of the filters with spatially uniform passband
• Data Management 1. Interfacing an individual investigator with the voluminous LSST data2. Scientific algorithm development for credible prototyping of pipelines3. Establishing catalog feature set and method for querying data base
• System Engineering1. Completing flow-down of scientific mission to perfomance specifications2. Generating a complete end-to-end simulator3. Establishing link between technical performance, cost, and schedule
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FPA Flatness Allocations Established
Sensor Module
5m p-v flatness over entire sensor surface
Raft Assembly
6.5m p-v flatness over entire surfaces of sensors
Focal Plane Assembly
10m p-v flatness over entire surfaces of sensors
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Integrating structure
Raft structure
AlNUP
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LSST highlights during the last year – Camera
• Strawman camera designed with 3 GPixel camera• Flow-down of science requirements to performance
requirements shows focal plane is achievable with CCD array
• Favorable first results with Hybrid CMOS sensors• Preliminary camera optical and mechanical design
completed• Vendor interaction confirms that refractive elements
and filters can be manufactured